Nature and management of salt-affected land in Saskatchewan

saskatchewan.ca/agriculture Contents

The nature of salt-affected soils...... 3 Types of salt-affected soils...... 3 Saline soils...... 3 Properties of saline soils...... 3 Effects of salt on plant growth...... 4 The properties and distribution of solonetzic salts...... 5 How soils become salinized — Sources of salts...... 5 The salinization process...... 6 1. Artesian discharge...... 6 2. Evaporitic rings around sloughs...... 7 3. Side hills seeps...... 8 Management of salt-affected soils...... 8 Management of saline soils...... 8 Managing the recharge area...... 8 Managing the discharge area...... 9 Crop selection...... 9 Forage crops for saline soils...... 12 Manure and other mulches...... 13 Fertilizers...... 13 Tillage and weed control...... 13 Chemical amendments...... 14 Drainage and leaching...... 14 Management of solonetzic soils...... 15 Investigating and measuring salinity investigating soil salinity...... 15 Measurement of soil salinity in the laboratory...... 16 Saturated paste method...... 16 The 1:1 Soil:Water method...... 16 Measurement of soil salinity in the field...... 16 Chemical reactions and criteria for salt-affected soils...... 18 Cation exchange reactions...... 18 Criteria for defining salt-affected soils...... 19 Summary...... 20

saskatchewan.ca/agriculture The Nature and Management of Salt-Affected Land In Saskatchewan

Part 1: The Nature of Salt-Affected Soils

Types of Salt Affected Soils The nature of salt-affected soils Many terms have been used to describe the Types of salt-affected soils different types of salt-affected soils. For Many terms have been used to describe the different example, to most farmers the word "alkali" means the "white spot where nothing grows". types of salt-affected soils. For example, to most Strictly speaking, most of these white areas farmers the word “alkali” means the “white spot where are saline rather than "alkali". Saline soils nothing grows”. Strictly speaking, most of these white have a high concentration of soluble salts. True alkali soils are low in soluble salts but areas are saline rather than “alkali”. Saline soils have a have a high sodium content and high pH (over high concentration of soluble salts. True alkali soils are 8.5). There are virtually no true alkali soils in low in soluble salts but have a high sodium content Saskatchewan. and high pH (over 8.5). There are virtually no true alkali Solonetzic soils ("burnout soils") have a high- soils in Saskatchewan. sodium hardpan layer and often have a saline Solonetzic soils (“burnout soils”) have a high sodium subsoil that restrict root growth. Therefore, they are a form of salt-affected soil. However, hard pan layer and often have a saline subsoil that their properties and management are restrict root growth. Therefore, they are a form of substantially different from those appropriate salt-affected soil. However, their properties and for saline soils. For more information on management are substantially different from those management of Solonetzic soils, refer to Solonetzic soils management bulletins. appropriate for saline soils. For more information on management of Solonetzic soils, refer to Solonetzic The primary purpose of this bulletin is to focus soils management publications. The primary purpose on the properties and management of saline Summary soils. ofSaline this and publication Solonetzic soils areis to major focus salt related on the soil problemsproperties in Saskatchewan and that require different management practices. of saline soils. Saline Soils Solonetzic or "burnout" soils usually have a high-sodium hardpan layer and a saline subsoil, resulting in poor crop establishment and root growth. Timely cultivation and deep plowing or deep ripping help to alleviate Saline soils Estimates of the total amount of saline land in problems with Solonetzic soils. FigureFigure 1. Areas1. Areas of salineof saline land land in Saskatchewan.in Saskatchewan. Map Map compiled by W. Saskatchewan vary widely but all agree that at Estimates of the total amount of saline land in Eilers,compiled G. Padbury by W. andEilers, B. McCann,G. Padbury based and onB. McCann,rural land based assessment Saline soils have a high concentration of soluble salts which reduces the ability of plants to take up water least several million acres are affected to Saskatchewan vary widely but all agree that at least dataon suppliedrural land by assessment SAMA. data supplied by; the and nutrients. The salts accumulate in certain areas due to ground water movement and evaporation. Until some degree. For example, salinity severalrecently, the million side hill seep acres model are was affected frequently used to tosome explain degree.soil salinization For in Saskatchewan.Saskatchewan In this Assessment Authority. model, water in excess of crop use moves underground from an up slope position to a local and adjacent deductions made by the Saskatchewan example,lower slope position. salinity However, deductions recent salinity made investigations by the suggest Saskatchewan that artesian discharge AssessmentAssessment from larger AuthorityAuthority suggest (SAMA) that suggest an area thatequivalent an area to 600,000 acres of zero production due to salinity equivalentscale, regional ground to 600,000 water aquifers acres is causing of zero salinity production in many areas due of Saskatchewan. to salinityoccurs In potholeoccurs within within the currently the currently cultivated cultivated area (G.A. areaPadbury, (G.A. 1986, personal communication, Figure 1). More landscapes, evaporitic rings of saline soil form around depressions due to ground waterdetailed mounds underneath maps of soil salinity are available from the Soil Survey Unit at the University of Saskatchewan. Padbury,the sloughs. 1986, personal communication, Figure 1). More information can be found on the Saskatchewan Soil

InformationSalinity can be controlled System in some (SKSIS) situations website once the. specific causes are understood. In the recharge area, improved drainage and water-efficient crop management practices will reduce the amount of water that enters the ground water system. In the discharge area, where salinity appears, it is important to establish Propertiesplant growth. of saline soils

SalineThere are soils no easy have or magical a high cures concentration for soil salinity. Salinity of must salts be thatregeared dissolve as both a inwater water. and soil The soluble salts include: sodium sulphate (Glauber’sproblem that requires salts), a long magnesium-term management sulphate strategy. (EpsomAlthough few salts) soils may and me calcium completely restoredsulphate to a (gypsum). In a few small areas normal state, the impact and spread of salinity can be reduced with appropriate management practices. chloride salts are present, but in the majority of cases sulphate salts are dominant. The solubility of various salts is provided in Table 1. While calcium sulphate (gypsum) and calcium carbonate (lime) are present in most saline subsoils, their low solubility means that they do not harm plant growth as much as the other salts. Gypsum is frequently present in soils as clearly identifiable white or buff-coloured crystals. Lime is more difficult to identify visually but its presence is easily verified by effervescence (fizzing) upon application of dilute acid. FigureFigure i. Salti. Salt crusts crusts on the on surface the surfaceof the soil. of the soil.

saskatchewan.ca/agriculture Figure iii. Solodized Solonetz soil profile.

Figure ii. Salt crystals and streaks in the soil.

For more information, contact: Agriculture Knowledge Centre Saskatchewan Agriculture Toll free: 1-866-457-2377 E-mail: [email protected] Summary Saline and Solonetzic soils are major salt related soil problems in Saskatchewan that require different management practices.

Solonetzic or "burnout" soils usually have a high-sodium hardpan layer and a saline subsoil, resulting in poor crop establishment and root growth. Timely cultivation and deep plowing or deep ripping help to alleviate problems with Solonetzic soils.

Saline soils have a high concentration of soluble salts which reduces the ability of plants to take up water and nutrients. The salts accumulate in certain areas due to ground water movement and evaporation. Until recently, the side hill seep model was frequently used to explain soil salinization in Saskatchewan. In this model, water in excess of crop use moves underground from an up slope position to a local and adjacent lower slope position. However, recent salinity investigations suggest that artesian discharge from larger scale, regional ground water aquifers is causing salinity in many areas of Saskatchewan. In pothole landscapes, evaporitic rings of saline soil form around depressions due to ground water mounds underneath the sloughs.

Salinity can be controlled in some situations once the specific causes are understood. In the recharge area, improved drainage and water-efficient crop management practices will reduce the amount of water that Detection of soil salinity is often easy. On saline soil, crops grow poorlyenters or the not ground at water all. Particularlysystem. In the discharge after a area, long where salinity appears, it is important to establish dry period, the salts may precipitate on the soil surface as a white crustplant growth. (Figure i). Where white crusts are not present it is sometimes possible to see streaks of salts by digging inThere the are soil no (Figureeasy or magical ii). cures for soil salinity. Salinity must be regeared as both a water and soil problem that requires a long-term management strategy. Although few soils may me completely restored to a Table 1. Solubility of salts in pure water at 20 C normal state, the impact and spread of salinity can be reduced with appropriate management practices. Salt Chemical formula Solubility (grams/litre)

Sodium sulphate Na2SO4 160

Magnesium sulphate MgSO4 300

Calcium sulphate CaSO4 2 Sodium chloride NaCl 264

Magnesium chloride MgCl2 353

Calcium chloride CaCl2 427 Calcium carbonate CaCO 0.01 3 Figure i. Salt crusts on the surface of the soil. It is not always possible to see the salts. Laboratory soil analyses, field measurements and vegetation can be used to confirm their presence. The salt content of soil can be estimated by measuring its electrical conductivity (EC), which is usually expressed in deciSiemens per metre (dS/m) or millimhos/cm (mmho/ Figure iii. Solodized Solonetz soil profile. cm). Laboratory analyses give the most accurate and detailed information but are slow and costly and provide information on only a small portion of the landscape. Routine soil tests for fertilizer recommendations usually FigureFigure ii. ii.Salt Salt crystals crystals and streaks and streaks in the soil. in the soil. include an EC measurement. When moderate levels of salinity appear at lower sample depths, special management practices, suchFor as more those information, discussed contact: in the “Management Agriculture Knowledge Centre of salt-affected soils” section, may be required. However, the EC measuredSaskatchewan during Agriculture soil tests for fertilizer recommendations are often different from those for which crop tolerances Toll free: 1-866-457-2377 are given. For an explanation of E-mail: [email protected] the differences between methods of measuring EC, see “Investigating and measuring salinity investigating soil salinity”. Direct field measurement of salinity is now possible using noncontracting conductivity metres such as the EM31 and EM38. Generally, plants that are affected by soil salinity have a bluish-green appearance. In cultivated land, Russian thistle, Kochia, foxtail barley and goosefoot species indicate areas of high salt concentration. In uncultivated saline areas, plants such as samphire (Salicornia rubra), desert salt grass (Distichlis stricta), and greasewood (Sarcobatus vermiculatus) are frequently dominant species. Effects of Salt on Plant Growth

TheEffects primary effectof salt of salts on inplant soils is togrowth deprive plants of water. Plants need both the water and the nutrients dissolved in it for proper growth. The sapThe in plantprimary roots effectcontains saltof saltswhich in attracts soils is to deprive plants of water. water into the plant via osmotic pressure. DissolvedPlants needsalts in both the soil the increase water the and osmotic the nutrients dissolved in it for pressureproper of growth. the soil solution. The sap This in decreases plant roots the contains salt which attracts ratewater at which into water the from plant the viasoil osmoticwill enter the pressure. Dissolved salts in roots. If the soil solution becomes too concentratedthe soil increase the plants the will slowlyosmotic starve, pressure though of the soil solution. This thedecreases supply of water the andrate dissolved at which nutrients water in thefrom the soil will enter the soil may be more adequate. Simply put, the salts preventroots. the If thewater soil and solutionnutrients from becomes entering thetoo concentrated the plants plantwill (Figure slowly 2). starve, though the supply of water and dissolved Figure 2. The presence of salts in the soil makes it Figure 2. The presence of salts in the soil makes it difficult for crops Somenutrients plants mayin the be adversely soil may affected be more by high adequate. Simply put, the salts todifficult take up water for and crops nutrients. to take up water and nutrients. concentrations of certain elements, such as boron. In Saskatchewan, however, this does not appear to be a major cause for concern; we are dealing primarily with a problem involving a high concentration of total salts. saskatchewan.ca/agriculture The Properties and Distribution of Solonetzic Soils Solonetzic soils are of three types: Solonetz, Solodized-Solonetz, and Solod. We will consider the characteristics of the most easily recognized Solonetzic soil: the Solodized-Solonetz. As shown in Figure iii, this soil consists of three main layers (sometimes called "horizons") each of which is different in composition.

A horizon - Surface layer consists of two distinct levels, the Ah and the Ae. The Ah layer is high in organic matter; the Ae is highly leached, coarse-textured, and can be acid.

Bnt horizon - Upper subsoil level contains high amounts of clay and exchangeable sodium and is tough, dense, and impermeable, interfering with the penetration of both water and plant roots. It has a distinct round-top columnar structure.

Csa, Cca horizon - Usually has a high concentration of soluble salts (including gypsum) and lime.

Thus it can be seen that Solodized-Solonetz soils exhibit the properties of acid soils in the A layer; sodic soils in the B layer; and saline soils in the C layer.

Solonetzic soils do not often occupy a large continuous area; they are more likely to appear as a number of distinct patches within a given field. In such fields wind and water Figure 3. Major areas in Saskatchewan where solonetzic soils occur. erosion may completely remove the A horizon, leaving small scattered depressions in which crops do very poorly. Such is the origin of the term "burn-out", which refers to these small depressions and the "burned" crop within them.

The distribution of major areas of solonetzic soils in Saskatchewan is shown in Figure 3.

Effects of Salt on Plant Growth

The primary effect of salts in soils is to deprive plants of water. Plants need both the water and the nutrients dissolved in it for proper growth. The sap in plant roots contains salt which attracts water into the plant via osmotic pressure. Dissolved salts in the soil increase the osmotic pressure of the soil solution. This decreases the rate at which water from the soil will enter the roots. If the soil solution becomes too concentrated the plants will slowly starve, though the supply of water and dissolved nutrients in the soil may be more adequate. Simply put, the salts prevent the water and nutrients from entering the plant (Figure 2).

Figure 2. The presence of salts in the soil makes it difficult for crops Some plants may be adversely affected by high to take up water and nutrients. concentrations of certain elements, such as boron. In Saskatchewan, however, this does not appear to be a major cause for concern; we are dealing primarily with a problem involving a high concentration of total salts. prevent the water and nutrients from entering the plant (Figure 2). The Properties and Distribution of Solonetzic Soils Some plants may be adversely affectedSolonetzic by soils high are ofconcentrations three types: Solonetz, of Sol certainodized-Solonetz, elements, and Solod. such We willas considerboron. the In characteristics of the most easily recognized Solonetzic soil: the Solodized-Solonetz. As shown in Figure iii, Saskatchewan, however, this does notthis soil appear consists toof three be amain major layers cause(sometimes for called concern; "horizons") we each are of dealingwhich is different primarily in composition. with a Summary problem involving a high concentration of total salts. Saline and Solonetzic soils are major salt related soil problems in Saskatchewan that require different A horizon - Surface layer consists of two management practices. distinct levels, the Ah and the Ae. The Ah layer is high in organic matter; the Ae is The properties and distributionhighly of solonetzic leached, coarse-textured, salts and can be Solonetzic or "burnout" soils usually have a high-sodium hardpan layerSolonetzic and a saline soils subsoil, are of resulting three types: in poor Solonetz, acid. Solodized-Solonetz, crop establishment and root growth. Timely cultivation and deep plowing or deep ripping help to alleviate problems with Solonetzic soils. and Solod. We will consider the characteristicsBnt horizon - Upper of subsoil the most level contains easily recognized Solonetzic soil: the Solodized-Solonetz.high amounts of clay and As exchangeable shown in sodium and is tough, dense, and Saline soils have a high concentration of soluble salts which reducesFigure the ability iii, this of plants soil consiststo take up of water three mainimpermeable, layers interfering (sometimes with the penetration called and nutrients. The salts accumulate in certain areas due to ground “horizons”)water movement each and of evaporation. which is different Until of both in watercomposition. and plant roots. It has a distinct recently, the side hill seep model was frequently used to explain soil salinization in Saskatchewan. In this round-top columnar structure. model, water in excess of crop use moves underground from an up slope position to a local and adjacent A horizon - Surface layer consists ofCsa, two Cca distinct horizon - Usuallylevels, has the a high Ah lower slope position. However, recent salinity investigations suggestand that the artesian Ae. Thedischarge Ah layer from is larger high in organicconcentration matter; of soluble the salts Ae (including is highly scale, regional ground water aquifers is causing salinity in many areas of Saskatchewan. In pothole gypsum) and lime. landscapes, evaporitic rings of saline soil form around depressions leached,due to ground coarse-textured, water mounds underneath and can be acid. the sloughs. Thus it can be seen that Solodized-Solonetz Bnt horizon - Upper subsoil level containssoils exhibit high the properties amounts of acid soils in the A layer; sodic soils in the B layer; and saline Salinity can be controlled in some situations once the specific causesof areclay understood. and exchangeable In the recharge sodium area, andsoils isin thetough, C layer. dense, and improved drainage and water-efficient crop management practices impermeable,will reduce the amount interfering of water with that the penetration of both water and Solonetzic soils do not often occupy a large enters the ground water system. In the discharge area, where salinityplant appears, roots. it isIt importanthas a distinct to establish round-top columnar structure. plant growth. continuous area; they are more likely to appear as a number of distinct patches within a given field. In such fields wind and water Csa, Cca horizon - Usually has a high concentration of soluble Figure 3. 3.Major Major area sareas in Saskatchewan in Saskatchewan where solonetzic where soils occur. erosion may completely remove the A There are no easy or magical cures for soil salinity. Salinity must besalts regeared (including as both gypsum)a water and and soil lime. Thus it can be seen that solonetzic soils occur. problem that requires a long-term management strategy. Although few soils may me completely restored to a horizon, leaving small scattered depressions in which crops do very poorly. Such is the origin of the term "burn-out", which refers to these small depressions and the "burned" crop within them. normal state, the impact and spread of salinity can be reduced withSolodized-Solonetz appropriate management soils practices. exhibit the properties of acid soils in the A layer; sodic soils in the B layer; andThe saline distribution soils of major in the areas C oflayer. solonetzic soils in Saskatchewan is shown in Figure 3.

Solonetzic soils do not often occupy a large continuous area; they are more likely to appear as a number of distinct patches within a given field. In such fields wind and water erosion may completely remove the A horizon, leaving small scattered depressions in which crops do very poorly. Such is the origin of the term “burn-out”, which refers to these small depressions and the “burned” crop within them. The distribution of major areas of solonetzic soils in Saskatchewan is shown in Figure 3.

How soils become salinized — Sources of salts Weathering of rocks and minerals: Over a period of time salts contained in rocks and minerals are gradually released into the soil by chemical and Figure i. Salt crusts on the surface of the soil. physical weathering. It is important to realize, however, that weathering, alone, seldom produces a soil salinity problem. Evaporation of ancient seas: In ancient times large areas of the province lay submerged under an immense sea. Gradually the sea disappeared, leaving marine shales with high concentrations of sodium salts. The movement of glaciers mixed the underlaying marine shale with surface deposits. In some FigureFigure iii. iii. Solodized Solodized Solonetz Solonetz soil soil profile. profile. areas, where glacial deposits are relatively shallow, the total supply of salts is large and the risk of salinity and other salt-related problems is very great. Irrigation water: All irrigation water contains some salt. Over an extended period of irrigation, salts will accumulate in the soil and a salinity problem may develop. Water from the Saskatchewan River system being used in major irrigation projects is of high quality and there is little risk of salt buildup. However, farmers Figure ii. Salt crystals and streaks in the soil. considering the development of small irrigation systems utilizing sources of water such as ponds, sloughs or ground water may face salinity problems. Any water source for irrigation should be analyzed to make certain For more information, contact: Agriculture Knowledge Centre Saskatchewan Agriculture saskatchewan.ca/agriculture Toll free: 1-866-457-2377 E-mail: [email protected] Part 2 How Soils Become Salinized - Sources of Salts

Weathering of rocks and minerals: Over a period of time salts contained in rocks and minerals are gradually released into the soil by chemical and physical weathering. It is important to realize, however, that weathering, alone, seldom produces a soil salinity problem.

Evaporation of ancient seas: In ancient times large areas of the province lay submerged under an immense sea. Gradually the sea disappeared, leaving marine shales with high concentrations of sodium salts. The movement of glaciers mixed the underlaying marine shale with surface deposits. In some areas, where glacial deposits are relatively shallow, the total supply of salts is large and the risk of salinity and other salt-related problems is very great.

Irrigation water: All irrigation water contains some salt. Over an extended period of irrigation, salts will accumulate in the soil and a salinity problem may develop. Water from the Saskatchewan River system being used in major irrigation projects is of high quality and there is little risk of salt buildup. However, farmers considering the development of small irrigation systems utilizing sources of water such as ponds, sloughs or ground water may face salinity problems. Any water source for irrigation should be analyzed to make certain that it will not result in a buildup of salts.

Most of the salinity associated with irrigation is not due to the addition of salts in irrigation water. Rather it is due to the redistribution of existing salts in the soil. Canal seepage or excess irrigation may raise the water table increasing the risk of salinity.

The Salinization Process

Salinity is more of a water problem than soil problem.

As described previously, weathering of rocks and minerals, alone, seldom produces a soil salinity problem. Because the salts are soluble, water moves and accumulates them in some parts of the landscape. To understand how these salt accumulations occur we must understand the movement of underground water. Salts can invade any type of soil, productive or unproductive, and when this invasion occurs, otherwise highly productive soils can be converted to unproductive soils.

A prerequisite forthat soil it willsalinization not result inis a a buildup free water of salts. table close enough to the soil surface to allowMost capillaryof the salinity (wick) associated action with to lift irrigation the water is not from due tothe the free addition water table to the soil surfaceof salts in (Figureirrigation 4). water. Generally, Rather it isif duethe towater the redistribution table is within of existing two metres (six ft.) ofsalts the in soil the surface,soil. Canal capillaryseepage or movement excess irrigation will carrymay raise water the towater the surface. However,table the increasing critical depththe risk variof salinity.es with soil texture. It is important to note that a high water table alone is not sufficient to cause soil salinization. It is not uncommonThe to salinizationfind sloughs process and depressions in Saskatchewan with water tables verySalinity near isto more the soil of a surfacwater probleme but because than soil ofproblem. the constant input of fresh runoff waterAs thedescribed net movement previously, weatheringof water in of these rocks andsloughs minerals, is downward alone, and hence they seldomare not produces salinized. a soil A salinityhigh water problem. table Because plus evaporationthe salts are soluble, SalineSaline areas areas are often are excessively often excessively wet due to a high water table. exceeding infiltrationwater movesare both and required accumulates for themthe salinization in some parts process. of the landscape. In other To wet due to a high water table. words, the salinizationunderstand process how these is solar- salt accumulationspowered. In occura semi we- aridmust climate, understand warm the movement of underground water. temperature, lowSalts humidity can invade and any wind type eva of soil,porate productive water orat unproductive,the soil surface and whenand this invasion occurs, otherwise highly cause salt accumulation.productive soils can be converted to unproductive soils. A prerequisite for soil salinization is a free water table close enough to the soil surface to allow capillary (wick) action to lift the water from the free water table to the soil surface (Figure 4). Generally, if the water table is within two metres (six ft.) of the soil surface, capillary movement will carry water to the surface. However, the critical depth varies with soil texture. It is important to note that a high water table alone is not sufficient to cause soil salinization. It is not uncommon to find sloughs and depressions in Saskatchewan with water tables very near to the soil surface but because of the constant input of fresh runoff water the net movement of water in these sloughs is downward and hence they are not salinized. A high water table plus evaporation exceeding infiltration are both required for the salinization process. In other words, the salinization process is solar-powered. In a semi-arid climate, warm temperature, low humidity and wind evaporate water at the soil surface and cause salt accumulation. SimplySimply put, put, salt salt accumulationaccumulation occurs occurs wheneverwhenever the the quantity quantity of waterof water leaving leaving the thesoil soil surfac surfacee by byevaporation evaporation exceeds exceeds the the quantityquantity of of water water that that enters enters the the soil soil through through rainfall, rainfall, runoff runoff accumulation, or irrigation. If this very simple principle is kept in mindaccumulation, it should be or relativelyirrigation. easy If this to very understand simple principle the situations is kept thatin mind are observedit should bein therelatively field. easy to understand the situations that are observed in the field. TheThe highhigh waterwater table table required required for for salinization salinization to to proceed proceed can can be be a aresult result of of several several ground ground water water movement movement patterns. patterns. Water Water enters entersthe ground the ground water watersystem system in the inrecharge the recharge area where area whereinfiltration infiltrationexceeds evaporation exceeds evaporation for at least fo partr at ofleast the part year. of Groundwater the year. Groundwater flows in water bearing layers called aquifers to flows in water bearing layers called aquifers to lower positions lower positions in the landscape. Salinity develops in the dischargein the landscape. area where Salinity the developswater is near in the the discharge soil surfac areae (within where twothe mwateretres) is andnear where the soil evaporation surface (within exce twoeds infiltration.metres) and What where follows isevaporation the discussion exceeds of the infiltration. major underground What follows conditions is the discussionresulting of FigureFigure 4. 4. Salts Salts build build up onup the on surface the surface where a shallow water table exists and where evaporation exceeds inthe high major water underground tables and conditions resulting in high water tables where a shallow water table exists and infiltration. salinizationand salinization in Saskatchewan. in Saskatchewan. where evaporation exceeds infiltration. 1.1. ArtesianArtesian Dischargedischarge ArtesianArtesian dischargedischarge occursoccurs where where the the pressure pressure in in the the aquifer aquifer is is sufficient sufficient toto force water to near the surface offorce the watersoil. Research to near the in Saskatchewan surface of the hassoil .shown Research that inartesian Saskatchewan discharge from aquifers of both glacial and has shown that artesian discharge from aquifers of both glacial and bedrock origin is the major factor responsible for high water tables and soil salinization. The term "bedrock" refers to deposits that were present prior to glaciation and does not mean solid rock. Thus, when we speak of bedrock aquifers, we saskatchewan.ca/agriculturemean sand layers within bedrock formations.

The mechanism of soil salinization by artesian discharge is shown by a generalized diagram in Figure 5. The water entry to the aquifer is in the upland area, for example, in the hummocky moraine of the Missouri Coteau. A salt crusts forms when In these hilly areas the recharge to the aquifer is concentrated primarily in saline water evaporates, sloughs or depressions and during periods of high precipitation or runoff. leaving the salt behind. These recharge areas may be at a great distance away form the saline area. Any factors such as excess summerfallow or cultivation which increases runoff into the sloughs will have the long term impact of increasing the water in aquifer and hence increasing salinization. However, saline areas have also been encountered where the adjacent upland is in native pasture.

If, as illustrated in Figure 5, the sand or gravel deposit of the aquifer "pinches out", then a pressurized situation results such that upward flow of water from the aquifer to the soil surface takes place. In such areas the water in farm wells comes close to the soil surface or may actually flow. There is a strong relationship between areas of flowing wells and areas Figure 5. Regional artesian discharge mechanism of salinization. of salinity problems.

In such areas the water table will be maintained close to the soil surface by the slow but constant upward movement from the aquifer. Land at or below the elevation to which water rises in wells will be at high risk for soil salinization. The actual amount of salinization will depend upon the pressure of the water in the aquifer, the salt content of the water and the extent to which the overlaying layers control upward movement. Simply put, salt accumulation occurs whenever the quantity of water leaving the soil surface by evaporation exceeds the quantity of water that enters the soil through rainfall, runoff accumulation, or irrigation. If this very simple principle is kept in mind it should be relatively easy to understand the situations that are observed in the field.

The high water table required for salinization to proceed can be a result of several ground water movement patterns. Water enters the ground water system in the recharge area where infiltrationSimply put, salt exceeds accumulation evaporation occurs whenever fo ther atquantity least of part of the year. water leaving the soil surface by evaporation exceeds the Groundwaterquantity of water thatflows enters in the water soil through bearing rainfall, runofflayers called aquifers to loweraccumulation, positions or irrigation. in the If this landscape. very simple principle Salinity is kept develops in in the mind it should be relatively easy to understand the situations dischargethat are observed area in thewhere field. the water is near the soil surface (within two metres) and where evaporation exceeds infiltration. What follows The high water table required for salinization to proceed can be is athe result discussion of several ground of water the movementmajor undergroundpatterns. Water conditions resulting Figure 4. Salts build up on the surface in entershigh the water ground tables water system and in the recharge area where where a shallow water table exists and infiltration exceeds evaporation for at least part of the year. salinizationGroundwater flows in Saskatchewan. in water bearing layers called aquifers to where evaporation exceeds infiltration. lower positions in the landscape. Salinity develops in the bedrock origin is the major factor responsibledischarge area for where high the waterwater is tables near the and soil surface (within 1. Artesian Dischargesoil salinization. The term “bedrock”two refers metres) to and deposits where evaporation that were exce presenteds infiltration. What follows is the discussion of the major underground conditions resulting Artesian dischargeFigureprior occurs 4. to Salts glaciation buildwhere up on theandthe surface doespressure not mean inin high the solid water aquifer rock. tables Thus, and is sufficient when we speak to of whebedrockre a shallow aquifers, water table we exists mean and sand layerssalinization within in Saskatchewan. bedrock formations. force water to nearwhe there evaporation surface exceeds of theinfiltration. soil . Research in Saskatchewan has shown that artesian1.The Artesian mechanism discharge Discharge of soil from salinization aquifers by ofartesian both dischargeglacial and is shown bedrock by a origin is the majorArtesian generalizedfactor discharge responsible diagram occurs where in for Figure the high pressure 5. Thewater in water the tables aquifer entry is andsufficientto the soil aquifer to salinization. is in the forceupland water area, to near for the example, surface of inthe the soil .hummocky Research in Saskatchewan moraine of the Missouri The term "bedrock"has refers shown that to artesian deposits discharge that from were aquifers present of both glacial prior and tobedrock glaciation and does not mean solidoriginCoteau. rock. is the In major Thus, these factor hilly when responsible areas we the for speak rechargehigh water of tablestobedrock the and aquifer soil aquifers, salinization. is concentrated we Theprimarily term "bedrock" in sloughs refers toor deposits depressions that were and present during prior periods to glaciation of andhigh mean sand layersdoes within not mean bedrock solid rock. formations. Thus, when we speak of bedrock aquifers, we meanprecipitation sand layers or within runoff. bedrock These formations. recharge areas may be at a great distance away form the saline area. Any factors such as excess summerfallow or The mechanism ofThecultivation soil mechanism salinization which of soil salinizationincreases by artesian by runoff artesian intodischarge discharge the sloughs is shown is shown bywill a have by the a long generalized diagram in Figure 5. The water entry to the aquifer is in the generalized diagramterm in impact Figure of 5.increasing The water the water entry in to aquifer the aquifer and hence is increasingin the upland area, for example, in the hummocky moraine of the Missouri Coteau. A salt crusts forms when In these hilly areas the recharge to the aquifer is concentrated primarily in A salt crusts forms when saline water upland area, for example,salinization. in However,the hummocky saline areas moraine have also of been the encounteredMissouri Coteau.salin wheree water evaporates,A salt crusts forms when sloughsthe adjacent or depressi uplandons and is during in native periods pasture. of high precipitation or runoff. leaving the salt behind.evaporates, leaving the salt behind. In these hilly areasThese the recharge recharge areas mayto thebe at aquifera great distance is concentrated away form the saline primarily area. in saline water evaporates, sloughs or depressiAnyIf, onsas factors illustrated and such during as excessin Figure periods summer 5, thefallow ofsand orhi cultivation ghor gravel precipitation which deposit increases of or the runoff runoff. aquifer into the “pinches sloughs will out”, have then the a pressurized situation long term impact of increasing the water in aquifer and hence increasing salinization. However, salineleavi ngareas the salt behind. These recharge areashaveresults also may suchbeen be encounteredthat at upward a great where flow thedistance adjacentof water upland awayfrom is the inform native aquifer thepasture. tosaline the soil area. surface takes place. In such areas the water Any factors such asin farmexcess wells summer comes closefallow to the or soilcultivation surface or which may actually increases flow. Thererunoff is intoa strong the relationship sloughs will between have areasthe If,of as flowing illustrated inwells and areas of salinity long term impact of increasing the water in aquifer and hence increasing salinization.Figure 5, the sand orHowever, saline areas have also been encountered where the adjacent upland is in native pasture.gravelproblems. deposit of the aquifer "pinches out", thenIn such a pressurized areas the water table will be situationmaintained results closesuchIf, asto the illustrated soil surface in by the thatslow upward but flowconstant of upward movement from water from the aquiferFigure 5, the sand or tothe the aquifer.soil surface Land at or below the elevation takesto which place. waterIn suchgravel rises in depositwells will beof theat areas the water in farmaquifer "pinches out", wellshigh comes risk forclose soil to salinization. The actual theamount soil surface of salinization or maythen a willpressurized depend upon actually flow. There is athe strong pressure relationship ofsituation the water inresults the aquifer, such the betweensalt content areas of of thatthe water upward and theflow extent of flowing wells and areas FigureFigure 5. 5. Reg Regionalional artesian artesian dischar dischargege mechanism mechanism of salinization. of salinization. to which the overlaying layers control of salinity problems.water from the aquifer upward movement.to the soil surface InSalinization such areas the by water artesian table will discharge be maintained has close been to goingthe soil onsurface over by the the slowmany but centuries constant upward since takes the last place. glaciers In receded such movement from the aquifer. Land at or below the elevation to which water rises in wells will be at high risk for soilfrom salinization. the settled The actual areas amount of Saskatchewan. of salinization will depend upon the pressure of the water in the aquifer,areas the water in farm the salt content of the water and the extent to which the overlaying layers control upward movement. wells comes close to Salinization by artesian discharge has been going on over the many centuries 2. Evaporitic rings around sloughs the soil surface or may since the last glaciers receded from the settled areas of Saskatchewan. In much of the thickly glaciated areas of Saskatchewan the landscape actually flow. There is is characterized by a series of undrained depressions called potholes a strong relationship 2 or sloughs. In these areas external drainage from the immediate site is . Evaporitic Rings Around Sloughs between areas of limited and most of the drainage is from the hillside to the depression. flowing wells and areas Figure 5. Regional artesianWhen these dischar sloughsge mechanism occur in upland of salinization. areas with no impediment to In much of the thickly glaciated areas of Saskatchewan the landscape downward drainage, they form the focus for ground water recharge. of salinity problems. is characterized by a series of undrained depressions called In recharge areas ground water mounds form but the net movement potholes or sloughs. In these areas external drainage from the immediate site In such areas the waterof water table is downward will be bothmaintained in the slough close and to in the the soilarea surfaceadjacent toby the slow but constant upward is limited and most of the drainage is from the hillside to the depression. movement from thethe aquifer. slough. However,Land at whenor below these thesloughs elevation occur in to lower which lying water areas inrises in wells will be at high risk for When these sloughs occur in upland areas with no impediment to downward which deep drainage is limited by an impermeable barrier or ground soil salinization. The actual amount of salinization will depend upon the pressureFlowing of the wells water are common in the in areas aquifer, where drainage, they form the focus for ground water recharge. In recharge areas the salt content of waterthe water pressure, and the the groundwater extent to moundswhich the can overlayingcause salinization. layers The control soilFlowin upward salinityg iswells caused movement. are by artesiancommon discharge. in ground water mounds form but the net movement of water is downward both areas where soil salinity is in the slough and in the area adjacent to the slough. However, when these caused by artesian saskatchewan.ca/agriculture sloughs occur in lower lying areas in which deep drainage is limited by an discharge. impermeable barrier or ground water pressure, the groundwater mounds can cause salinization. The combination of a high water table and evaporation results in an evaporitic ring of saline soil around the edge of the depression as shown in Figure 6. Other depressions including dugouts and ditches may also form salinity in this manner.

Above: Local side hill seep in the Figure 6. Evaporitic ring mechanism of salinization Ponteix area. 3. Side Hills Seeps

Where glacial deposits are very shallow and rest upon impermeable bedrock shale, salinization can be caused by lateral water movement along the impermeable shale surface (Figure 7). In this mechanism of soil salinization the recharge area and the discharge area are near each other and may be in the same field. With this type of Figure 7. Local side hill seep mechanism of salinization salinization the changes in hydrologic cycle that have been brought about by cultivation of prairie lands has been a major factor in causing and increasing the severity of salinity. For similar reasons, changing cropping practices may allow a farmer to control saline Salinization by artesian discharge has been going on over the many centuries since the last glaciers receded from the settled areas of Saskatchewan.

Salinization by artesian discharge has been going2. Evaporitic on over the Rings many Around centuries Sloughs since the last glaciers receded from the settled areas of Saskatchewan. In much of the thickly glaciated areas of Saskatchewan the landscape 2. Evaporitic Rings Around Sloughs is characterized by a series of undrained depressions called potholes or sloughs. In these areas external drainage from the immediate site is limited and most of the drainage is from the hillside to the depression. In much of the thickly glaciated areas of SaskatchewanWhen these the sloughs landscape occur in upland areas with no impediment to downward is characterized by a series of undrained depressions drainage, called they form the focus for ground water recharge. In recharge areas potholes or sloughs.Flowin In theseg wells areas are common external in drainageground waterfrom moundsthe immediate form but site the net movement of water is downward both is limited and most areasof the where drainage soil salinity is from is the hillsidein the slough to the and depression. in the area adjacent to the slough. However, when these When these sloughscaused occur by inartesian upland areas withsloughs no impediment occur in lower to downward lying areas in which deep drainage is limited by an discharge. drainage, they form the focus for ground water impermeablerecharge. In barrier recharge or ground areas water pressure, the groundwater mounds Flowing wells are common in ground water moundscan formcause but salinization. the net movement The combination of water of a ishigh downward water table both and evaporation results in an evaporitic ring of areas where soil salinity is saline soil around the edge of the depression as shown in Figure 6. Other depressions including dugouts and in the slough and inditches the area may adjacent also form to salinity the slough. in this manner. However, when these caused by artesian sloughs occur in lower lying areas in which deep drainage is limited by an discharge. impermeable barrier or ground water pressure, the groundwater mounds can cause salinization. The combination of a high water table and evaporation results in an evaporitic ring of salinecombination soil around of athe high edge water of the table depression and as shown in Figure 6. Other depressions including dugouts and ditches may also form salinity in this manner. evaporation results in an evaporitic ring of saline soil around the edge of the depression as shown in Figure 6. Other depressions including dugouts and ditches may also form salinity in this manner.

3. Side hills seeps Where glacial deposits are very shallow and rest upon impermeable bedrock shale,

salinization can be caused by lateral water movement along the impermeable shale surface (Figure 7). In this mechanism of soil salinization the recharge area and the Figure 6. Evaporitic ring mechanism of salinization. Above: Local side hill seep in the Figure 6. Evaporitic ring mechanism of salinization discharge area are near each other and Ponteix area. may be in the same field. With this type of salinization the changes in hydrologic cycle that have been brought 3. Side Hills Seeps about by cultivation of prairie lands has been a major factor in causing and increasing the severity of salinity. Where glacial deposits are For similar reasons, changing cropping practices may allow a farmer to control saline seeps. However, recent very shallow and rest upon salinity investigations indicate that side hill seeps are not as common in Saskatchewan as has been reported inimpermeable bedrock Above: Local side hill seep in the shale, salinization can be Figureother 6. areas Evaporitic in the ring Northern mechanism Great of salinization Plains of North America. caused by lateral water Ponteix area. movement along the The causes of soil salinity in a particular field are generally not as simple 3.as Sidedescribe Hills Seepsabove. A combination of impermeable shale surface these mechanisms is usually involved. (Figure 7). In this Where glacial deposits are mechanism of soil very shallow and rest upon salinization the recharge area and the discharge Managementimpermeable bedrock of salt-affected area are near each other soilsshale, salinization can be and may be in the same caused by lateral water field. With this type of movement along the Figure 7. Local side hill seep mechanismManagement of salinization of saline soils salinization the changes in In recentimpermeable years there shale has surface been growing hydrologic cycle that have been brought about by cultivation of(Figure prairie lands7). In ha thiss been a major factor in causing and increasing the severity of salinity. For similarconcern reasons,mechanism changing over the ofcr oppingincreasingsoil practices problem may allow a farmer to control saline of croppingsalinization saline the rechargeareas. Although Saskatchewanarea and the had discharge soils affected by salinity longarea before are agriculturalnear each other settlement, man’s and may be in the same activities have aggravated the problem field. With this type of Figure 7. Local side hill seep mechanism of salinization. increasing the incidence, extent and Figure 7. Local side hill seep mechanism of salinization salinization the changes in severityhydrologic of soil cycle salinity. that The have increasing beenproblem brought is due about to bychanges cultivation to surfaceof prairie drainage lands has andbeen cropping a major factor techniques in causing that and are increasing not as water the efficient as the severity of salinity. For similar reasons, changing cropping practices may allow a farmer to control saline native Prairie grasslands. There are no easy or magical cures for soil salinity. Salinity must be regarded as a production limitation in the same way as stoniness and steep slopes. Unique management practices may always be required. For example, many saline soils may never be suitable for summerfallow crop production. Water management is the key to controlling salinity. The degree to which water movement can be managed determines the feasibility of controlling the salinity problem. Therefore it is at least as important to manage recharge as it is to cope with discharge of ground water.

Managing the recharge area Any excess moisture that recharges the ground water can eventually cause salinity in a discharge area. Preventing the accumulation and deep percolation of excess water in the recharge area is important for

saskatchewan.ca/agriculture controlling the salinization process at its point of origin. In some mechanisms such as in the artesian system the recharge area may be very extensive and far away from the salinity problem. It may not be practical to control recharge in these cases. For that reason, prior to attempting recharge management, an investigation should be conducted to determine the salinity system and to accurately identify the area and the amount of recharge that may be occurring locally. Excess water in recharge areas is often the result of natural and manmade ponding, excess accumulations of snow, the growing of annual instead of perennial crops and excessive summerfallowing. Recharge of ground water is most likely during months or years when rainfall or snowmelt runoff is high and where soils are coarse-textured. Control of ground water recharge can be obtained through removal of the excess water by improving drainage or cropping practices that use up more of the moisture. Wherever possible, recharge water should be used locally. Recharge water is usually non-saline and should be treated as a valuable resource. Surface drainage using an open trench or buried pipe will remove the water before it has a chance to infiltrate and recharge the ground water table. In some cases sloughs or ponds may be consolidated to provide a water source for irrigation or other uses. Subsurface drainage may also be effective if a suitable outlet is available. Care should be exercised when altering natural drainage. Some drainage practices may aggravate local salinity problems and permission should also be obtained from the Water Security Agency. Continuous cropping or growing perennial forages uses up more recharge water than summerfallow cropping. See Figure 8. Regardless of crop rotation length, adequate fertilization will encourage better use of soil moisture. Where recropping is attempted, snow trapping may be used to increase soil moisture and to distribute snowmelt water uniformly. Snow should be managed in a way that barriers will not accumulate excessive amounts of snow in one location. Deep-rooted forages grow very well where there is a high water table in the recharge area. Alfalfa is the deepest rooted and highest moisture use forage, so it is the preferred species for recharge control. For more information on forage crop management please contact the Saskatchewan Ministry of Agriculture’s Agriculture Knowledge Deep rooted forages grow very well where there is a high water table in Centre, toll free 1-866-457-2377. the recharge area. Alfalfa is the deepest rooted and highest moisture use forage, so it is the preferred species for recharge control. For more Managing the discharge area information on forage crop management please contact Saskatchewan Managing the discharge area is difficult because there are excesses of both water and salts. The objective of discharge area Agriculture's Agriculture Knowledge Centre, toll free 1-866-457-2377. management is to establish crop growth while attempting to move the salt downward. In most dryland situations it is unlikely Managing The Discharge Area that the salts can be removed entirely. However, lowering the salt concentration in the top 30 cm will often improve production dramatically. Even so, particularly reclaimed saline areas will Managing the discharge area is difficult because there are excesses of always require special management practices. both water and salts. The objective of discharge area management is to establish crop growth while attempting to move the salt downward. In Crop selection most dryland situations it is unlikely that the salts can be removed Crop selection is the main management practice that a farmer entirely. However, lowering the salt concentration in the top 30 cm will can use to combat a soil salinity problem in the discharge often improve production dramatically. Even so, particularly reclaimed area. Leaving the soil bare promotes evaporation and salt accumulation at the surface. Therefore fallowing or growing non- saline areas will always require special management practices. tolerant crops aggravates salinity problems.

The tolerance of various annual, forage and vegetable crops is Figure 8. Available soil water under various crop Crop Selection shown in Table 2. Barley, sunflower and safflower are the most Fisystems,gure fall 8. 1978 Available (Brown, USDA, soil Montana).water under various crop systems, fall Crop selection is the main management practice that a farmer can use to saskatchewan.ca/agriculture 1978 (Brown, USDA, Montana). combat a soil salinity problem in the discharge area. Leaving the soil bare promotes evaporation and salt accumulation at the surface. Therefore fallowing or growing nontolerant crops aggravates salinity problems.

The tolerance of various annual, forage and vegetable crops is shown in Table 2. Barley, sunflower and safflower are the most tolerant of the annual crops grown in Saskatchewan. In most saline management cropping situations, barley becomes the mainstay of the cropping program. While continuous cropping to one annual plant species is not a general agronomic recommendation, it may have a role in management of moderately saline soils. Close attention to disease problems will be required and if disease becomes significant, changes in the cropping pattern will be required. tolerant of the annual crops grown in Saskatchewan. In most saline management cropping situations, barley becomes the mainstay of the cropping program. While continuous cropping to one annual plant species is not a general agronomic recommendation, it may have a role in management of moderately saline soils. Close attention to disease problems will be required and if disease becomes significant, changes in the cropping pattern will be required.

Table 2. The relative tolerance of crops to salinity*1 Degree of Salinity Tolerated (Electrical Conductivity)*2 Annual Field Crops Forage Crops Vegetable Crops Soybeans Red Clover Peas Field Beans Alsike Beans Fababeans Timothy Onions Peas Celery Non to Slightly Saline (0-4) Corn Radishes Cucumber Carrots Corn (sweet) Canola Reed Canary Meadow Tomatoes Flax Fescue Lettuce Mustard Intermediate Wheat Cabbage Wheat Crested Wheatgrass Potatoes Fall Rye*3 Bromegrass Peppers Moderately Saline (4-8) Oats Alfalfa Spinach Two-Row Barley*3 Sweet Clover*3 Asparagus Safflower Garden Beets Sunflower Six-Row Barley*3 Sugar Beets Barley may produce some Altai Wild Ryegrass crop but this land best Russian Wild Ryegrass suited to tolerant forages. Slender Wheatgrass Tall Wheatgrass Severely to Very Severely to Beardless Wild Saline (8-16) Ryegrass Levonns alkaligrass Alkali sacaton Salt Meadow Grass Crops within each group are listed in order of increasing salt tolerance. *1 Differences of one or two places in the rank may not be significant. *2 Rating for salt content in dS/m conductivity in saturated paste. For more information about conductivity, see the “Investigating and measuring salinity investigating soil salinity” section. *3 These crops are not tolerant of flooding, which is common in some saline soils.

If economic yields of annual crops cannot be maintained on saline land, then perennial forage production is the only management practice that can be recommended. Forage crop mixtures for varying levels of soil salinity and degrees of spring flooding is provided in Table 3. As a general rule, mixtures of grasses and legumes are seeded so that at least some plant species will establish in

saskatchewan.ca/agriculture even the most saline area and the more valuable species will grow on less saline portions of the field. The major reason for failure of forage crops to establish is seeding into seedbeds that are too loose and seeding depths that are too great. Forage crops, in general, are small seeded crops that require careful seedbed preparation and shallow seeding for successful establishment. Consult forage crop pubilcations for details on varieties and seeding practices. Table 3. Forage crops for saline soils and flooded ares, 15 to 18 cm (6 to 7 in.) row spacings*1 Seeding rate for hay or pasture Salinity rating*2 Crop or mixture lb./ac. or kg/ha Soils with little or no flooding (up to two weeks) Bromegrass+Russian wild ryegrass+alfalfa 4+4+4 Bromegrass+slender wheatgrass+alfalfa 4+4+4 Russian wild ryegrass+alfalfa 6+3 Altai wild ryegrass+alfalfa 10+3 Slight to moderate (2-6 dS/m) Crested wheatgrass+alfalfa 7+3 Altai wild ryegrass 11 Slender wheatgrass+sweet clover (short-term stands and 8+6 not over 1 week of flooding) Bromegrass+Russian wild ryegrasss+slender wheatgrass 4+4+4 Altai wild ryegrass+alfalfa 10+3 Severe (6-10 dS/m) Altai wild ryegrass 11 Tall wheatgrass (moist districts of seepage areas) 12 Russian wild ryegrass+slender wheatgrass 4+4 Altai wild ryegrass+alfalfa 10+3 Very severe (10-15 dS/m) Altai wild ryegrass 10 Tall wheatgrass (moist districts of seepage areas) 12 Spring flooded (two to five weeks) Reed canarygrass + bromegrass 4+6 Reed canarygrass+timothy 4+4 Little or none (up to 2 dS/m) Timothy+bromegrass 4+6 Altai wild ryegrass+alfalfa 10+3 Altai wild ryegrass 11 Reed canarygrass + bromegrass 4+6 Reed canarygrass+bromegrass +slender wheatgrass 4+6+6 Slight to Moderate (2-6 dS/m) Altai wild ryegrass+alfalfa 10+3 Altai wild ryegrass 11 Altai wild ryegrass+alfalfa 10+3 Slender wheatgrass 8 Severe to Very Severe (6-15 dS/m) Altai wild ryegrass 11 Tall wheatgrass 12 *1 For more information, see Forage Crop Production Guide or contact the Agriculture Knowledge Centre toll free at 1-866-457-2377.

saskatchewan.ca/agriculture *2 Rating for salt content in DS/m conductivity in saturated paste. For more information about conductivity see the “Investigating and measuring salinity investigating soil salinity” seciton. Forage crops for saline soils 1. The standard grasses: Crested wheatgrass and Bromegrass show relatively equal tolerance to salts. These standard grasses do not establish nearly as well under salinity stress as do the salt tolerant types. Outside the saline area they establish more easily and are more competitive with weeds. Consequently, the standard grasses should be a part of any seeding mixture for saline land, because of the wide range of salinity levels usually present. 2. The legumes: Sweet clover and Alfalfa have salt tolerances somewhere between standard grasses and salt- tolerant grasses. Alfalfa and sweet clover are the backbone of salinity reclamation. Both fix their own nitrogen when properly inoculated and are capable of prolific growth under good moisture conditions. Sweet clover establishes easily and grows vigorously in saline conditions. It is a proven green manure crop for soil improvement. The one drawback is its short life (biennial). Alfalfa is a long-lived perennial legume. Alfalfa has a deep tap root system and once established provides excellent production for many years. Alfalfa should be a part of any forage crop mix for salt-affected land. 3. Common salt-tolerant grasses: Altai wild ryegrass, Tall wheatgrass, Russian wild ryegrass and Slender wheatgrass show relatively equal salt tolerance, but have different roles in saline soil management. Slender wheatgrass exhibits greatest ease of establishment followed by Russian wild ryegrass, Tall wheatgrass and Altai wild ryegrass. Slender wheatgrass is short-lived and best suited to short-term rotations. Under dry conditions slender wheatgrass is more salt tolerant than Tall wheatgrass. Altai wild ryegrass is a grass with very limited creeping ability and is most useful in pasture situations. It has a high degree of tolerance to soil salinity and has the deepest rooting system of any grass species, but is slow to establish. Russian wild ryegrass is similar to Altai wild ryegrass in salt tolerance and is a bunch grass most useful in pasture situations. However, Russian wild ryegrass is not as deep-rooted as Altai. Russian wild ryegrass often establishes very slowly and patience will be required when establishing this crop. Tall wheatgrass is the most salt-tolerant and will produce the largest yield of forage hay. It is also the most tolerant to flooding and extremely wet conditions, and as such, is most useful in seriously salt-affected areas. While Tall wheatgrass is the most salt-tolerant, it is not the most palatable or nutritious livestock feed and will require mixing with other forage species in any feeding program. These grasses, although highly salt tolerant are slow to establish and do not compete with weeds during establishment. Weed encroachment in the seedling stage, whether under saline or normal soil conditions, is undoubtedly the biggest handicap to satisfactory forage establishment. Under saline conditions typical problem weeds include wild barley (“foxtail”), kochia, the goosefoots, and pigweeds. For more information on weed control, see the Guide to Crop Protection or contact the Agriculture Knowledge Centre. Because of their high salt tolerance, the accepted salt tolerant grasses should be a part of the seeding mixture for saline land. 4. The “exotic” grasses: Shoshone beardless wild ryegrass, Levonns alkaligrass, Salt Meadow Grass and Alkali sacaton exhibit remarkable tolerance to very high salinity levels. Limited testing suggests decreasing tolerance in the order listed. These grasses appear to thrive at conductivity levels of 20 dS/m or more. The very small seeded Salt Meadow Grass and Levonns alkali-grass, however, are very difficult to establish and require extra firmness of seedbed and very shallow seeding. The larger seeded Shoshone beardless wild ryegrass, being close to Russian wild ryegrass in seed size, appears to establish similarly to Russian saskatchewan.ca/agriculture 4. The "exotic" grasses: Shoshonewild ryegrass beardless under normal wild soil ryegrass, conditions and Levonns has a creeping alkali- habit enabling it to fill into bare areas. Seed of these exotic grasses may grass, Salt Meadow Grassnot and be widelyAlkali available sacaton and may exhibit be expensive. remarkable tolerance to very high salinity levels.5. LimitedKochia (or testing “summer Cypress”)suggests has decreasinglong been considered tolerance a weed. in the order listed. These grassesRecently, appear agronomists to thrive have notedat conductivity its ability to colonize levels bare of saline 20 dS/m or more. The very smallpatches seeded where Saltno other Meadow plants will Grass grow. Kochia and will Levonns reseed itself alkali-grass, however, are verynaturally difficult if allowed to establishto, but the soil and must requir be workede extra at least firmness once each year or else the Kochia stand will ‘self-suffocate’. Kochia may be used of seedbed and very shallowas seeding. a feed, but it The can be larger toxic under seeded some circumstances,Shoshone especiallybeardless wild ryegrass, being close towhen Russian fed in excessive wild ryegrass amounts. For in more seed information size, appears contact the to establish similarly to RussianAgriculture wild ry egrassKnowledge under Centre. normal soil conditions and has a creeping habit enablingThe it precise to fill place into of bare Kochia areas. in salinity Seed management of these is not exotic yet known, grasses may not be widely availablebut research andis continuing. may be expensive. Manure and other mulches 5. Kochia (or "summer Cypress")Application has of longhigh rates been of manure, considered 40 to 60 tonnes/hectare,a weed. have Recently, agronomists haveimproved noted crop its establishment ability to andcolonize crop yields bare on salinesaline soils. Manure patches where no other plantsincreases will the grow.organic matter Kochia content will and reseed water-holding itself capacity of the soil. In this way more water is available to plants even though salts are naturally if allowed to, butpresent. the soil Manure must also be adds worked nutrients atand least improves once the structure or tilth each year or else the Kochiaof the stand soil. will ‘self-suffocate'. Kochia may be Altai wild ryegrass growing on saline soil. Altai wild ryegrass used as a feed, but it canNeither be toxic fertilizers under nor manuresome actuallycircumstances, get rid of the salts. Better crop growing on saline soil. especially when fed in excessivegrowth can amounts. result from fertilizer For more or manure information and more moisture will be used. Manure will also assist in water contact the Agriculture Knowledgemovement through Centre. the soil to leach the salts down. For short periods of time, when the manure mulch is present on the soil surface, it reduces evaporation and concentration of salts at the surface of the soil. Other forms of mulch such as straw probably perform the The precise place of Kochia insame salinity function. management When a mulch is presentis not andyet significant known, butprecipitation research occurs, is somecontinuing. leaching of salts out of the surface layer may even be possible.

Manure and Other Mulches Fertilizers Application of high rates of manure,On moderately 40 to saline 60 soilstonnes/ the usehectare, of phosphate have fertilizers improved with the cr seedop of establishment cereal grains has given and excellent crop yields on saline soils. Manureyield increases increases. Nitrogenthe organic fertilizers matte do notr usuallycontent provide and much water-holding yield response incapacity the most seriously of the salt-soil. In this way more water is availableaffected to plants area but even if salinity though is scattered salts within are a present.field the nitrogen Manure fertilizer also should adds be nutrientsapplied according and to soil test recommendations for the non-saline areas. Interpretation of nitrogen soil tests is often complicated by the improves the structure or tilth presenceof the soil.of salts, so areas which are obviously saline should not be sampled. Special attention should be paid to the location of available nitrogen in the soil profile under saline soil conditions. If the subsoil is saline it will Neither fertilizers nor manure usuallyactually contain get a highrid ofconcentration the salts. of Betternitrate-nitrogen crop growth which may ca notn beresult useful from to plants. fertilizer or manure and more moisture willPerennial be used. grass cropsManure will respond will also strongly assist to high in application water movement rates of fertilizer through in years ofthe average soil orto above- leach the salts down. average rainfall. It should be emphasized that fertilizer use is one additional aid in crop production on some moderately saline soils. However, fertilizer use will not solve the problem of salinity itself in these soils and does not result in any For short periods of time, when“neutralization” the manure of the mulch salts. is present on the soil surface, it reduces evaporation and concentration of salts at the surface of the soil. Other forms of mulch such as straw probably perform the same function. When a mulchTillage is present and weed and control significant precipitation occurs, some leaching of salts out of the Since salt concentrations in subsoil are frequently higher than they are at the immediate soil surface, shallow surface layer may even be possible.

Fertilizers saskatchewan.ca/agriculture On moderately saline soils the use of phosphate fertilizers with the seed of cereal grains has given excellent yield increases. Nitrogen fertilizers do not usually provide much yield response in the most seriously salt- affected area but if salinity is scattered within a field the nitrogen fertilizer should be applied according to soil test recommendations for the non-saline areas. Interpretation of nitrogen soil tests is often complicated by the presence of salts, so areas which are obviously saline should not be sampled. Special attention should be paid to the location of available nitrogen in the soil profile under saline soil conditions. If the subsoil is saline it will usually contain a high concentration of nitrate-nitrogen which may not be useful to plants.

Perennial grass crops will respond strongly to high application rates of fertilizer in years of average or above average rainfall.

It should be emphasized that fertilizer use is one additional aid in crop production on some moderately saline soils. However, fertilizer use will not solve the problem of salinity itself in these soils and does not result in any "neutralization" of the salts. tillage is generally recommended for saline soils. Deep tillage may, in many cases, bring more salts to the surface and make the problem worse. Tillage practices should maintain all possible residues at the soil surface. Shallow seeding is just as critical on saline soils as it is on normal soils. Timeliness of seeding is particularly important for small seeded crops such as flax, alfalfa, sweet clover and canola. These crops should be seeded early to have them germinate when surface salt concentrations may be temporarily lowered. A number of weeds mentioned earlier are very tolerant of salts. Chemical weed control along with tillage is essential to get crops, particularly forages, properly established.

Chemical amendments There are no chemical amendments that will “neutralize” the salts present in the soil. The salts that are causing the problem are neutral salts (neither acid nor base). In areas of the world where true alkali soils exist, the application of elemental sulphur or gypsum can have beneficial effects. Elemental sulphur applications assist in reducing the pH where an extremely high pH is the problem. The gypsum applications supply calcium to replace the sodium and improve the soil structure. However, as we have no true alkali soils in Saskatchewan these applications would be of no benefit. In most areas of saline soils, gypsum (calcium sulphate) is one of the major salt constituents and the application of additional gypsum would simply be supplying more of the same material that is already present in abundance.

Drainage and leaching One way to reclaim saline soils and restore their productivity is to install drainage (such as tile drains) and then provide a source of leaching water. In irrigation areas drainage for salinity control may be feasible because there is usually enough water to leach the excess salts out of the soil. However, in dryland areas drainage is seldom an economically viable proposition. Desalinization of dryland soils takes place very slowly upon installation of drainage without extra water to leach the salts out of the soils. Most installations of underground perforated plastic pipe for drainage and reclamation of soils in Saskatchewan have not been successful. These failures have been due largely to the fact that the soils in which they were installed were extremely fine-textured and slow draining and no provision was made for the application of leaching water. The installation of perforated plastic drain pipes is not recommended as a reclamation practice for saline soils unless a specific site investigation suggests that the practice will work and a permit has been obtained. In some dryland areas it may be possible to improve surface drainage in recharge areas where small sloughs or other water bodies are contributing to the problem. For example, in areas where local saline seeps have been identified, it may be possible to determine a source of surface water (such as an upland slough) which is contributing to the problem and to drain that particular water body. Drainage is a very controversial issue because one might always be concerned with where the water is going. There is little point in solving a problem on one field if it is simply contributing to the further development of a problem on an adjacent field. For this and other reasons, it is presently illegal to undertake drainage of any kind without a permit. A new possibility for drainage and leaching exists in those areas where salinity is caused by artesian discharge from shallow glacial aquifers containing only moderately saline water dominated by calcium and magnesium salts. It may be possible to utilize this water for irrigation and at the same time lower the pressure of the water in the aquifer and provide the necessary conditions for leaching the salts downward. However, this technology saskatchewan.ca/agriculture Management of Solonetzic Soils The main areas of Solonetzic soils in Saskatchewan are shown in Figure 3. It is not the purpose of this bulletin to present detailed information on Solonetzic soils. For further information on Solonetzic soils the reader is referred to Solonetzic soils management bulletins.

The major management tool available for managing solonetzic soils is timeliness of tillage operations. Tillage operations and seeding must be done when the soil is at the correct moisture content. If the soil is worked when it is too wet, the structure breaks down completely. If tillage is left too late, the soil bakes and it becomes almost impossible to get proper penetration of tillage implements.

Deep plowing or deep ripping to a depth of 45-75 cm (18-30 in.) is a reclamation practice for Soloetzic soils which has proven beneficial in Alberta and North Dakota and, more recently, in the Weyburn area of Saskatchewan. However, deep plowing at insufficient depth or where the subsoil is very saline or stoney can do more harm than good.

Before proceeding with any deep plowing projects the farmer should seek professional advice and refer to Solonetzic soils bulletins to be certain that his problem is in fact one of Solonetzic soils and that the plowing operation has some chance of success.

Deep plowing is not a management or reclamation practice for saline soils Management of Solonetzic Soils needs to beThe proven. main areas of Solonetzic soils in Saskatchewan are shown in Figure 3. It is not the purpose of this bulletin to present detailed information on Solonetzic soils. For further information on Solonetzic soils the Managementreader of issolonetzic referred soilsto Solonetzic soils management bulletins. The main areas of Solonetzic soils in Saskatchewan are shown in Figure 3. It is notT thehe purpose major managementof this publication tool to availablepresent detailed for managing information solonetzic soils is timeliness of tillage operations. Tillage on Solonetzicoperations soils. For andfurther seeding information must on be Solonetzic done when soils, theplease soil is at the correct moisture content. If the soil is worked refer to Solonetzicwhen it soilsis too management wet, the structure publications. breaks down completely. If tillage is left too late, the soil bakes and it The majorbecomes management almost tool availableimpossible for managing to get prop solonetzicer penetration soils is of tillage implements. timeliness of tillage operations. Tillage operations and seeding must be done when the soil is at the correct moisture content. If the soil is Deep plowing or deep ripping to a depth of 45-75 cm (18-30 in.) is a reclamation practice for Soloetzic soils worked when it is too wet, the structure breaks down completely. If tillage is leftwhich too late,has the proven soil bakes beneficial and it becomes in Alberta almost and impossible North Da tokota and, more recently, in the Weyburn area of get properSaskatchewan. penetration of tillage However, implements. deep plowing at insufficient depth or where the subsoil is very saline or stoney can do more harm than good. Deep plowing or deep ripping to a depth of 45 to 75 cm (18 to 30 in.) is a reclamation practice for Soloetzic soils, which has proven beneficial in AlbertaBefore and North proceeding Dakota and, with more any recently, deep in plowing the Weyburn projects area ofthe farmerDeep plowing should is expensive seek but professional breaks up advice and refer to Saskatchewan.Solonetzic However, soils deep bulletins plowing toat insufficientbe certain that depth his or problem where istheDee in hardpan pfact plowing andone brings of is Solonetzic upexpensive calcium to help soilsbut breaks and that up the plowinghardpan This durum wheat field in the Weyburn area the subsoiloperation is very saline has or some stoney chance can do more of success. harm than good. reclaim true Soloetzic soils. Deep plowing is notand recommended brings up for calcium saline soils. to help reclaim true Soloetzic responded very well to deep plowing, even in a wet Before proceeding with any deep plowing projects the farmer should soils. Deep plowing is not recommended for saline year. seek professionalDeep plowing advice and is refer not to a Solonetzic management soils publications or reclamation to be certain practicesoil s.that his for problem saline is soilsin fact one of Solonetzic soils and that the plowing operation has some chance of success. Deep plowing is not a management or reclamation practice for saline soils.

Investigating and measuring salinity investigating soil salinity The causes of soil salinity vary from site to site and so do the appropriate controls. Because salinity control is often costly and risky, an investigation should be carried out if possible. Detailed salinity investigations consist of: • Collecting and interpreting: • Existing water well information; • Aerial photographs; and • Soil survey maps; • Field inspections to observe the extent and severity of salinity; This durum wheat field in the Weyburn area • DrillingDee to:p plowing is expensive but breaks up the hardpan respondedThis durum very wellwheat to deep field plowing, in the even Weyburn in area • Determineand brings geologic up calcium material; to help reclaim true Soloetzic arespon wet year.ded very well to deep plowing, even in a wet • Identifysoils. water Deep bearing plowing layers; is not and recommended for saline year. • Installsoil waters. table observation wells and piezometers (see Figure 9); and • Monitoring to determine: • Water table elevations; and

• Response to recommended controls. In most cases, a detailed salinity investigation requires hydrological expertise and expensive equipment. For more information, contact the Agriculture Knowledge Centre or PFRA offices.

saskatchewan.ca/agriculture Part 4: Investigating and Measuring Salinity Investigating Soil SalinityFarmers play an essential role in investigating salinity because Part 4:of Investigatingtheir long term experience and Measu in thering local Salinity area. Investigating Soil SalinityThe causes of soil salinity vary from site to site and so do the appropriateIf the salinity controls. is recent Because or it is salinchangingity control in size, is thereoften maycostly be and risky,some an hopeinvestigation for reclamation should beif the carried recharge out ifmechanism possible. is clearly The causesidentified of soiland salinitymanageable. vary If fromsalinity site is known to site to and have so been do the appropriate controls. Because salinity control is often costly and Detailedpresent salinity for many investigations years, it is unlikely consist toof: be reclaimable for normal risky, cropan investigation production. The should occurrence be carried of flowing out wellsif possible. or regional waterCollecting tables within and two interpreting metres (six ft.) of the soil surface may Detailedindicate salinity - a existing ground investigations waterwater wellrecharge information consist system of: that is too large for a single farmer - aerial to photographs control. - soil survey maps MeasurementCollecting and of soil interpreting salinity in the laboratory Saturated paste method Field- existing inspections water to well observe information the extent and severity of In this method water is added to a given weight of soil until the salinity- aerial photographs soil is -saturated soil survey and justmaps reaches the flow point. This condition is referred to as a saturated paste. The saturated paste is allowed Drilling to to sit for - approximately determine geologic two hours material to reach equilibrium. At that timeField the waterinspections present into the observe paste is the extracted extent with and the severity aid of of salinity - identify water bearing layers a suction - installapparatus. water This table extract observation is referred wells to asand the piezometers saturation Figure 9. Water table well and piezometer extract(see. The Figure electrical 9) conductivity of this extract is then Figure 9.Water table well and piezometer measured. The higher the salt concentration in a specific soil construction. Note: Many small diameter farm wells Drilling to conare, struction.indeed, piezometers Note: Many because small they diameter intercept water the higher Monitoring- determine will be to the determinegeologic conductivity material of the saturation extract. The farmfrom awell specifics are, water-bearing indeed, piezometers layer. conductivity - identify- water is expressed table water elevations bearing in deciSiemens layers per metre (dS/m) or because they intercept water from a millimhos - install- response per centimetre water to recommendedtable (mmho/cm). observation controls wells and piezometersspecific water-bearing layer. Conductivity(see Figure values 9) determined on a saturation extract have been the standardFigure method 9.Wat ofer measuringtable well soiland piezometer salinity by research workers throughoutIn most the cases, world fora detailed many years. salinity Thus, investigation almostcon struction.all available requires Note: researchhydrological Many data small on diameter crop tolerance is related to the saturationexpertise extract and values.expensive equipment. For more information, contact the Monitoring to determine Agriculture Knowledge Centre or PFRAfarm offices. well s are, indeed, piezometers Unfortunately, - water tablethe determination elevations of salt content of the saturation extract methodbecau seis too they costly intercept and time water from a consuming - response to allow to this recommended method to Farmersbe used controls routinely. play an essential role in investigatingspecific water-bearing salinity because layer. of their long term experience in the local area. The 1:1 Soil:Water method InUse most the 1:1 cases, Soil to aWater detailed quick salinitytest during investigation routine soil analysis requires hydrological If theexpertise salinity isand recent expensive or it is changing equipment. in size For, there more may information,be some hope contact the forfor reclamation fertilizer recommendations. if the recharge mechanism In this method is clearly a given identified weight and of manageable.Agwaterriculture is added If Knowledgesalinity to the issame known weightCentre to hav of or esoil beenPFRA to provide present offices. a for suspension. many years, it is unlikelyThis suspension to be reclaimable is allowed forto equilibratenormal crop for production. a short period The ofoccurrence time of Farmers(approximatelyflowing wells play or one regional an half essential hour). water At tables rolethis time within in investigatinga conductivitytwo metres ( probesix salinity ft.) isof the because soil of surfacetheirinserted maylong in indicate theterm suspension experience a ground and water conductivityin the recharge local reading systemarea. isthat made is too directly. large Detailed salinity investigations forThus, a single laborious farmer paste to control. preparation and vacuum extraction is not required. consist of many steps including The actual conductivity value obtained by the 1:1 suspension method is drilling to identify the origin of the If the salinity is recent or it is changing in size, there may be some hope excess ground water. fornot reclamationas easily interpreted if the asrecharge that for the mechanism saturated paste. is clearly However, identified recent and research work has determined the relationship between the values Measurement of Soil Salinity in the Laboratorymanageable. If salinity is known to have been present for many years, it isobtained unlikely by tothe be different reclaimable methods. for This normal relationship crop production. varies for soils The of occurrence different texture as outlined in Table 4. Saturated Paste Method of flowing wells or regional water tables within two metres (six ft.) of the soil In this method water is added to a givensurface weight of may soil untilindicate the soil a groundis saturated water and re justcharge reaches system the flow that is too large Detailed salinity investigations consist of Measurement of soil salinity in the field Detailedpoint. salinity This condition investigations is referred to as a saturatedfor a single paste. farmer The saturated to control. paste is allowed to sit for approximatelymany steps including two hours drilling toto identifyreach theequilibrium. The development At that time of the non-contacting water present terrainin the paconductivityste is extracted metres with in the consist of many steps including aidorigin of a ofsuction the excess apparatus. ground water. This extract ispast referred decade to has as thebeen saturation a major advancement extract. The in electrical the capability conductivity to assess drillingof this to identifyextract isthe then origi measured.n of the The higher the salt concentration in a specific soil the higher will be the excessconductivitysaskatchewan.ca/agriculture ground water.of the saturation extract. The conductivity is expressed in deciSiemens per metre (dS/m) or Measurementmillimhos per ofcentimetre Soil Salinity (mmho/cm). in the Laboratory Conductivity values determined on a saturation extract have been the standard method of measuring soil Saturatedsalinity by Paste research Method workers throughout the world for many years. Thus, almost all available research data on In thiscrop method tolerance water is related is added to the saturationto a given extract weight values. of soil until the soil is saturated and just reaches the flow point. This condition is referred to as a saturated paste. The saturated paste is allowed to sit for approximately two hours to reach equilibrium. At that time the water present in the paste is extracted with the aid of a suction apparatus. This extract is referred to as the saturation extract. The electrical conductivity of this extract is then measured. The higher the salt concentration in a specific soil the higher will be the conductivity of the saturation extract. The conductivity is expressed in deciSiemens per metre (dS/m) or millimhos per centimetre (mmho/cm).

Conductivity values determined on a saturation extract have been the standard method of measuring soil salinity by research workers throughout the world for many years. Thus, almost all available research data on crop tolerance is related to the saturation extract values. Measurement of Soil Salinity in the Field

The development of non-contacting terrain conductivity metres in the past decade has been a major advancement in the capability to assess saline soil conditions in the field. The most common units in use today are the Geonics EM31 and EM38. The EM31 unit can assess conductivity to depths of approximately six metres with the instrument in the vertical orientation and approximately three metres with the instrument in the horizontal orientation. EM31 units are usedsaline extensively soil conditions for in thea vari field.ety The of most purposes common units besides in use today salinity are the monitoring, Geonics EM31 andincluding EM38. The tracing pollutants in undergroundEM31 water unit can systems. assess conductivity The EM to 31depths unit of approximatelyis rather large, six metres requires with the approximatelyinstrument in the vertical five or orientation and approximately three metres with the instrument in the horizontal orientation. EM31 units 10 minutes to set up and break aredown used atextensively the beginning for a variety andof purposes end ofbesides a job salinity and monitoring, quickly includingbecomes tracing a physical pollutants in burden in extensive field investigations. Forunderground this reason water thesystems. EM31 The EM31 in now unit is used rather large,only requires in situations approximately where five thereor 10 minutes is a to set up specific desire for the greater depthand break capability down at the of beginning this instrument. and end of a job and quickly becomes a physical burden in extensive field investigations. For this reason the EM31 in now used only in situations where there is a specific desire for the greater depth capability of this instrument.

The most popular instrument nowTable in 4. Theuse relationship is the ofEM38. electrical conductivityThe EM38 (EC, dS/m) unit of senses the 1:1 suspension the average to that obtained or by bulk the saturated conductivity paste of approximately the surface 1 ormethod. 1.2 metres with the instrument in the vertical position and approximately 0.5 metres with the instrument in the horizontal position. Thus,Salinity the rating readings for top 60 cmit provides(2 ft.) are of direct application to the root zone of crops, makingTexture the EM38Non-saline unit Slightlya useful saline sensorModerately of soil saline salinitySeverly insaline the Veryfield. severely The saline EM38 is extremely light and portable and, with the addition of aEC, carrying 1:1 suspension strap, (dS/m) can be used to monitor changes in the bulk conductivity Sand,of the Loamy surface metre as one traverses the field. In practice, an operator traverses the field notes the deflectSandion of the needle,0-0.7 and at0.8-1.5 appropriate1.6-3.0 points in the3.1-6.1 traverse, pauses6.2+ to Sandy Loam 0-0.8 0.9-1.6 1.7-3.3 3.4-6.6 6.7+ place the unit in the horizontal position.Loam 0-0.9 1.0-1.8 1.9-3.6 3.7-7.2 7.3+ Clay Loam 0-1.0 1.1-2.0 2.1-4.0 4.1-8.0 8.1+ The EM38 unit is of most value toClay, people Organic who know0-1.1 and understand1.2-2.2 soil,2.3-4.4 especially 4.5-8.8soil texture 8.9+and soil moisture. Both soil texture and soilSaturation moisture Extract, ECand 0-2the interaction2-4 of the two4-8 factors affect8-16 the readings16+ obtained. All other factors beingEC equal, Ratios of Saturatedcoarse-textur Extract to 1:1ed Suspension (light) for soils Various will Soil Textures read much less than fine-textured (heavy) soils and dry soils will read much less than wetTexture soils. For example,EC, saturated extract/1:1in non-saline suspension soils, a reading of five to 10 may be obtained in a dry gravel pit, a readingSand, of Loamy 15 Sandto 30 in2.6 a dry pasture in a sandy soil, and a reading of 70 to 80 in a Regina heavy clay summerfallowSandy field Loam in which the2.4 water is at field capacity throughout the rooting zone. Thus, especially for readings less thanLoam 100, it is necessary2.2 to use a soil probe or auger to verify the reason for the reading obtained with the EM38.Clay Loam 2.0 Clay, Organic 1.8 Apart from the moisture and textureThe most factors popular noted instrument above, now in theuse is major the EM38. factor The EM38 unit senses the average or bulk conductivity of approximately the surface influencing readings is the salt content,1 or 1.2 metres and with a thehigh instrument salt content in the vertical overrides position andall other factors. Readings much above 100approximately in either 0.5 themetres horizontal with the instrument or vertical in the horizontalposition position. can only be obtained by elevated saltThus, concentrations, the readings it provides and are the of direct higher application the reading, to the root thezone higher the salt concentration. Forof crops,exampl makinge at the the EM38 edge unit a ofuseful salt sensor lakes of soil such salinity as in the field. The EM38 is extremely light and portable and, with the addition of a Muskiki Lake east of Saskatoon,carrying readings strap, canof be700 used to to 900 monitor are changes obtained. in the bulk conductivity of the surface metre as one traverses the field. In practice, an operator traverses the field notes the deflection of the needle, and at appropriate The major points to remember whenpoints inusing the traverse, the EM38pauses to to place assess the unit salinity in the horizontal are to position. suspend the unit just above the Theground EM38 unit surf is aceof most when value totraversing people who knowthe fieldand understand so that changes can be noted and be preparedsoil, especially to soil use texture a soil and probe soil moisture. or auger Both soil to texture verify and the soil message being received. moisture and the interaction of the two factors affect the readings obtained. All other factors being equal, coarse-textured (light) soils will The EM38 conductivity metre is used to read much less than fine-textured (heavy) soils and dry soils will read Theassess salinityEM38 in the conductivity field. EM units can also be useful in soil assessment of any kind in non-saline metre is used to assess environments. Particularly in rechargesaskatchewan.ca/agriculture areas, EM readings are useful in locating salinity in the field. and mapping coarse-textured soils which may be allowing greater entry of water into the system, possibly causing greater salinization at some lower elevation.

When recording the EM readings, it has become customary to record the readings in the vertical orientation first, followed by a slash and the reading in the horizontal orientation. Thus, an EM reading of 150/100 would mean a reading of 150 in the vertical position and a reading of 100 in the horizontal position. much less than wet soils. For example, in non-saline soils, a reading of five to 10 may be obtained in a dry gravel pit, a reading of 15 to 30 in a dry pasture in a sandy soil, and a reading of 70 to 80 in a Regina heavy clay summerfallow field in which the water is at field capacity throughout the rooting zone. Thus, especially for readings less than 100, it is necessary to use a soil probe or auger to verify the reason for the reading obtained with the EM38. Apart from the moisture and texture factors noted above, the major factor influencing readings is the salt content, and a high salt content overrides all other factors. Readings much above 100 in either the horizontal or vertical position can only be obtained by elevated salt concentrations, and the higher the reading, the higher the salt concentration. For example at the edge of salt lakes such as Muskiki Lake east of Saskatoon, readings of 700 to 900 are obtained. The major points to remember when using the EM38 to assess salinity are to suspend the unit just above the ground surface when traversing the field so that changes can be noted and be prepared to use a soil probe or auger to verify the message being received. EM units can also be useful in soil assessment of any kind in non-saline environments. Particularly in recharge areas, EM readings are useful in locating and mapping coarse-textured soils which may be allowing greater entry of water into the system, possibly causingChemical greater Reactions salinization and Criter atia somefor Salt-Affected lower elevation. Soils.

When recording the EM readings, it has becomeCation customary Exchange Reactions to record the readings in the vertical orientation first, followed by a slash and the reading in theClay horizontalparticles in soils orientation. carry a negative Thus, charge. an Because EM reading of this they of attract150/100 cations would (positively charged ions) mean a reading of 150 in the vertical positionto and their surfacea reading as illu ofstrated 100 in in the the diagram horizontal below (Figure position. 10).

Chemical Reactions reactions and Criter andia for criteria Salt-Affected for Soils. Cationsalt-affected Exchange Reactions soils Clay particles in soils carry a negative charge. Because of this they attract cations (positively charged ions) toCation their surface exchange as illustrated reactions in the diagram below (Figure 10). Clay particles in soils carry a negative charge. Because of this they attract cations (positively charged ions) to their surface as illustrated in the diagram below (Figure FigureFigure 10. 10. Th Thee negatively negatively charged charged clay and clay organic and matter organic particles matter attract particles cations fromattract cations soil to exchange sites. 10). from soil to exchange sites. Exchange reactions take place between the Exchangecations on reactions the clay take surfaceplace between and the the cations cations on the in clay the surface soil solution.and the cations in the soil solution. The ability of a soil to retain the exchange cations is referred to as cation exchange capacity (CEC). The The ability of a soil to retain the exchange cationscation isexchange referred capacity to as of cation a soil is exchangeexpressed in centimolescapacity of (CEC). positive The charge cation per kilogram of soil (cmol(+)/kg) or milliequivalents per 100 grams of soil (me/100 g). Figureexchange 10. The negatively capacity charged of aclay soil and isorganic expressed matter particles in centimoles attract cations from of positive charge per kilogram of soil (cmol(+)/kg) or soilmilliequivalents to exchange sites. per 100 grams of soil (me/100Organic g). matter particles also carry negative charges. The entire complex of clay and organic matter and mixed clay-organic matter material in soils is referred to as the exchange complex. ExchangeOrganic reactionsmatter takeparticles place between also carry the cations negative on the clay charges. surface andThe the entire cations complex in the soil solution. of clay and organic matter and mixed Theclay-organic ability of a soil matter to retain materialthe exchange in cations soils isis referred referred to as to cation as the exchange exchange capacity (CEC).complex The . cation exchange capacity of a soil is expressed in centimoles of positive charge per kilogram of soil (cmol(+)/kg)The reaction or milliequivalents that takes per place 100 grams between of soil (me/100 the exchange g). complex and the soil solution is similar to that which Organictakes placematter particles in a water also carry softener negative as charge illustrateds. The entire in complexthe diagram of clay and (Figure organic matter11). The and softener is “charged” with sodium mixedions clay-organic(Na +) which matter attach material themselvesin soils is referred to to the as the negatively exchange complex charged. exchange resin. Calcium ions (Ca++) in the hard water enter the water softener where

they displace some of the sodium ions. Figure 11. The principle of cation exchangeThe calcium in soils is similarions toremain the exchange “stuck” of to the magnesium and calcium for sodiumexchange in a water softener. resin in the softener and the The reaction that takes place betweendisplaced the exchange sodium complex ions andgo thewith soil thesolution water is similar to that which takes place in a water softener asthat illustrated leaves in the diagram softener. (Figure 11). The softener is "charged" with sodium ions (Na +) which attach themselves to the negatively charged exchange resin. Calcium ions (Ca++)

in the hard water enter the water softener where they displace some of the sodium ions. The calcium ions Figure 11. 11. Th Thee principle principle of cation of cation exchange exchange in soils is insimilar soils to is the similar exchange to the of exchange of To measure the cation exchange capacity remain "stuck" to the exchange resin in the softener and the displaced sodium ions go with the water that magnemagnesiumsium and and calcium calcium for sodium for sodiumin a water in softener. a water softener. leaves the softener. of a soil the exchange complex is saturated

The reaction that takes place between the exchange complex andTo measured the soil solution the cation is similar exchange to that capacity which of a soil the exchange complex is saturated with a particular takessaskatchewan.ca/agriculture place in a water softener as illustrated in the diagram (Figurecation, 11). which The issoftener then replaced is "charged" with witha second cation. The total amount of the first cation that was driven off by sodium ions (Na +) which attach themselves to the negatively chargedthe second exchange cation isresin. then Calcium measured. ions This (Ca++) procedure is laborious, time consuming and expensive. Therefore, in the hard water enter the water softener where they displace itsome is not of economically the sodium ions. feasible The tocalcium use this ions method for large numbers of samples. remain "stuck" to the exchange resin in the softener and the displaced sodium ions go with the water that leaves the softener. Fortunately, for Saskatchewan soils it is possible to make an estimation of the cation exchange capacity of a soil if the clay and organic matter contents of that soil are known. To measured the cation exchange capacity of a soil the exchange complex is saturated with a particular cation, which is then replaced with a second cation. The total amount of the first cation that was driven off by the second cation is then measured. This procedure is laborious, time consuming and expensive. Therefore, it is not economically feasible to use this method for large numbers of samples.

Fortunately, for Saskatchewan soils it is possible to make an estimation of the cation exchange capacity of a soil if the clay and organic matter contents of that soil are known. with a particular cation, which is then replaced with a second cation. The total amount of the first cation that was driven off by the second cation is then measured. This procedure is laborious, time consuming and expensive. Therefore, it is not economically feasible to use this method for large numbers of samples. Fortunately, for Saskatchewan soils it is possible to make an estimation of the cation exchange capacity of a soil if the clay and organic matter contents of that soil are known. The equation relating cation exchange capacity to the clay and organic matter content of soils is: CEC (cmol(+)/kg or me/100 g) = 0.5 X (% clay) + 2.0 X (% organic matter)

Criteria for defining salt-affected soils Soils with a dominance of calcium on the exchange complex will be well granulated and in good physical condition. They will be well aerated and will allow water to enter. Soils with sodium on the exchange complex have very poor structure. They “puddle” when wet, not allowing water to enter readily. They also bake and crust badly when dry. The above phenomena have lead to the often quoted expression: “Soft water makes hard land. Hard water makes soft land.” From the above discussion it can be seen that the amount of sodium present on the exchange complex is a critical criterion that will affect the physical condition of the soil. In this publication, salt-affected soils are defined as: • Saline soils — soils that have a highThe concentration specific criteria of usedsalts to but define have different a low concentrationsoil types of saline of exchangeablesoils are given in Table 5. sodium; • Sodic soils — soils that have a low concentrationTable 5. Chemical of salts, criteria but for have different a high types concentration of salt-affected of exchangeable soils sodium. Alkali soils are sodic soils which also have a high pH; and Conductivity Exchangeable Sodium Percentage Sodium Adsorption Ratio • Saline-Sodic soils — soils that haveType both a high concentration of salts and a high concentration of (dS/m) (ESP) (SAR) exchangeable sodium. The specific criteria used to define differentSaline soil types greater of than saline 4 soils are less given than 15in Table 5. less than 13 Saline- Table 5. Chemical criteria for different types of salt-affectedgreater soils. than 4 less than 15 greater than 13 Sodic

Type Conductivity (dS/m) SodicExchangeable less sodium than 4 percentage greater (ESP) thanSodium 15 absorption ratio (SAR)greater than 13 Saline greater than 4 less than 15 less than 13 Saline-Sodic greater than 4 lessThe than exchangeable 15 sodium percentage (ESP)greater is one of than the 13major criteria utilized to separate salt-affected Sodic less than 4 greatersoils into than three 15 categories. The exchangeablegreater sodium than percentage 13 is defined as:

The exchangeable sodium percentage (ESP)ESP = is one Exchangeable of the major Na criteria X 100 utilized to separate salt-affected soils into three categories. The exchangeable sodium Cation percentage exchange capacity is defined as:

ES = Note: Concentrations Exchangeable in cmol(+)/kg Na or me/100X 100 g Cation exchange capacity Note: Concentrations in cmol(+)/kg or me/100To determine g ESP, total exchange capacity and exchangeable sodium measurements must be performed. Since these procedures are difficult and laborious, an estimate of exchangeable sodium is frequently To determine ESP, total exchange capacityobtained and exchangeablefrom the saturation sodium extract. measurements must be performed. Since these procedures are difficult and laborious, an estimate of exchangeable sodium is frequently obtained from the saturation extract. By measuring the cations present in the saturation extract it is possible to determine the sodium absorption ratio (SAR). Sodium absorption ratio is defined as: By measuring the cations present in the saturation extract it is possible to determine the sodium absorption

Note: Concentration in millimoes (+) or milliequivalents per litre of extract. In many references works on soil salinity the SAR is quoted and hence we have to have some knowledge of the interpretation of saskatchewan.ca/agriculture SAR values. It conveniently turns out that SAR and ESP values are approximately numerically equivalent up to values of about 25. The specific equation relating these two is given below:

ESP = (1.47 X SAR) - 1.26 (0.0147 X SAR) + 0.99

ratio (SAR). Sodium absorption ratio is defined as: Note: Concentration in millimoes (+) or milliequivalents per litre of extract. In many references works on soil salinity the SAR is quoted and hence we have to have some knowledge of the interpretation of SAR values. It conveniently turns out that SAR and ESP values are approximately numerically equivalent up to values of about 25. The specific equation relating these two is: ESP = (1.47 X SAR) - 1.26 (0.0147 X SAR) + 0.99 Summary Saline and Solonetzic soils are major salt related soil problems in Saskatchewan that require different management practices. Solonetzic or “burnout” soils usually have a high-sodium hardpan layer and a saline subsoil, resulting in poor crop establishment and root growth. Timely cultivation and deep plowing or deep ripping help to alleviate problems with Solonetzic soils. Saline soils have a high concentration of soluble salts which reduces the ability of plants to take up water and nutrients. The salts accumulate in certain areas due to ground water movement and evaporation. Until recently, the side hill seep model was frequently used to explain soil salinization in Saskatchewan. In this model, water in excess of crop use moves underground from an up slope position to a local and adjacent lower slope position. However, recent salinity investigations suggest that artesian discharge from larger scale, regional ground water aquifers is causing salinity in many areas of Saskatchewan. In pothole landscapes, evaporitic rings of saline soil form around depressions due to ground water mounds underneath the sloughs. Salinity can be controlled in some situations once the specific causes are understood. In the recharge area, improved drainage and water-efficient crop management practices will reduce the amount of water that enters the ground water system. In the discharge area, where salinity appears, it is important to establish plant growth. There are no easy or magical cures for soil salinity. Salinity must be regeared as both a water and soil problem that requires a long-term management strategy. Although few soils may me completely restored to a normal state, the impact and spread of salinity can be reduced with appropriate management practices. For more information, contact the Agriculture Knowledge Centre toll-free at 1-866-457-2377 or [email protected].

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