SF-1617 Evaluation of for Suitability for Tile Performance

Larry J. Cihacek The presence of salts and high water which the tile functions properly when Associate Professor, Science tables in North Dakota soils due to an fi rst installed, but within a few growing extended climactic wet cycle recently seasons, the effi cacy or performance Dave Franzen has stimulated interest in the installa- may appear to decrease and areas Extension Soil Specialist tion of tile drainage systems. The tile in fi elds may not appear to drain as controls the and encour- expected. This may be from changes Xinhua Jia ages the leaching and removal of salts in soil chemistry due to the removal Assistant Professor, Ag and Biosystems Engineering from the soil above the tile lines. This of salts and resulting soil swelling improves soil productivity, culminating and dispersion rather than improper Roxanne Johnson in improved crop yields. installation of the tile drains. Extension Water Quality Associate Other advantages of drainage include Due to the high cost of tile installation, Tom Scherer lower crop production risks, increasing poor subsurface drainage performance Extension Agricultural Engineer management options, reduced seasonal can have a signifi cant economic impact wetness and improved timeliness of on a farming operation. fi eld operations. On the other hand, the cost of installation and maintenance, The loss of subsurface drainage issues, outfl ow management, effectiveness may be due, in part, to the need for water in dry seasons and tile being placed in or below a zone of strained relationships with neighbors sodic or saline-sodic subsoils. The sodic may be disadvantages associated or saline-sodic characteristics often are with drainage. not noted readily at the soil surface. Characteristics of saline, sodic and Although soil drainage is usually saline-sodic soils are shown in Table 1. successful, instances may occur in

Table 1. Characteristics of saline, sodic and saline-sodic soils (from USDA Handbook no. 60).

Photo by Hans Kandel Exchangeable Sodium Electrical Sodium Adsorption Soil type pH Conductivity (EC)† Percentage (ESP) Ratio (SAR)

mmhos/cm % Saline <8.5 >4 <15 <13 Sodic >8.5 <4 >15 >13 Saline-sodic <8.5 >4 >15 >13

† mmhos/cm – millimhos per centimeter; 1mmhos/cm = 1 deci-Siemen per meter (dS/m) August 2012 www.ag.ndsu.edu ■ 1 Tile installed in soils or subsoils that Knowledge of Soil Series Most drainage system designers and are sodic or saline-sodic often will installers evaluate soil texture in a fi eld The occurrence of a specifi c soil series, function normally for a period of time as a part of the system design process. types or map units on a parcel of land after installation because these soils However, soil chemical characteristics under consideration for drainage can often contain divalent (2+ charged) are not normally part of this process. be obtained from a county soil survey calcium (Ca2+) and magnesium Preliminary evaluation of soil chemical map or online from the U.S. Depart- (Mg2+) salts that maintain the soil characteristics can be accomplished ment of -Natural Resources materials in an adequately fl occulated using the soil chemical data embedded Conservation Service’s Web Soil Survey state (maintain soil structure) under in the Web Soil Survey. In addition, (http://websoilsurvey.nrcs.usda.gov). natural moisture conditions. a soil drainage suitability rating for The soil series listed in Tables 2 and 3 North Dakota soils is available in the are soils that are most likely to have But, when the soils are drained Web Soil Survey. and excess water is removed, the dispersion problems when drained. divalent salts also are removed, with Also, soils with the greatest probability the water leaving the soil material of drainage problems are those soils Using Web Soil Survey above or around the tile line saturated with pH values greater than 8.5 in The Web Soil Survey is an Internet- with monovalent (1+ charged) sodium the surface or subsurface zones. based digital product provided by the (Na+). When this occurs, the soils lose A pH greater than 8.5 often indicates USDA Natural Resources Conservation their natural structure and become high sodium (Na+) saturation, which Service at http://websoilsurvey.nrcs. dispersed. This could cause sealing of could lead to tile sealing when salts usda.gov. Most soils in North Dakota the soil above and/or around the tile are leached out of the soil above the can be evaluated from maps and lines, resulting in ineffective drainage. tile line. If any of the soils listed in information contained in the Web Soil Reduced drainage performance is Tables 2 and 3 occur in the parcel of Survey. Figures 1-4 are an example of more likely to occur in fi nely textured land to be drained, the soil chemical how to access this information from (silty or clayey) soils and to a much characteristics need to be evaluated. a personal computer or other device lesser extent in coarser-textured with Internet access. (sandy) soils. Once drainage performance is reduced, little can be done economically to restore the Table 2. Soil series with sodium-affected subsoils. effectiveness of the drainage system. Aberdeen Ferney Mekinock Ryan However, producers can take Camtown Harriet Miranda Stirum Cathay Heil Nahon Totten precautions prior to tile installation Cavour Larson Niobell Turton on soils where drainage performance Cresbard Lemert Noonan Uranda is likely to occur. These precautions Daglum Letcher Ojata Easby Ludden Playmoor include: (1) knowing the soil series Exline Manfred Ranslo (soil types) in the fi eld under consider- ation for drainage, (2) evaluating the soil chemical characteristics for Table 3. Soil series with potentially sodium-affected subsoils. each of the soils mapped in the fi eld, Antler Fargo Karlsruhe Reis (3) evaluating the soil properties for Arveson Fossum Kratka Rockwell suitability for having tile installed and Augsburg Fram Koto Roliss (4) verifying soil types and chemical Bearden Gilby Lamoure Rosewood Bohnsack Glyndon Lowe Thiefriver characteristics (items 1 and 2 above) Borup Grano McKranz Ulen by deep soil sampling and testing. Clearwater Grimsted Mantador Vallers Using these precautions can help Colvin Gunclub Marysland Viking Cubden Hamerly Moritz Wheatville avoid installation of drain lines Divide Hedman Nielsville Winger where poor subsurface drainage Eaglesnest Hegne Northcote Wyndmere performance is likely. Elmville Holmquist Putney Wyrene Enloe Huffton Regan

2 ■ SF-1617 Evaluation of Soils for Suitability for Tile Drainage Performance Figure 1. To access the Web Soil Survey (http://websoilsurvey.nrcs.usda.gov), click on the large green “START WSS” button near the top of the page.

Evaluation of Soil Chemical Characteristics Soil chemical properties can be evalu- ated utilizing the “Soil Data Explorer” tab in the Web Soil Survey. Once a parcel of land is selected, choosing the “Soil Chemical Properties” menu in “Soil Data Explorer” provides options for soil evaluation, which will bring up a menu of several chemical characteristics that can be evaluated.

The characteristic of interest for this soil evaluation is the sodium adsorption ratio (SAR). Clicking on “Sodium Adsorption Ratio” will bring up an interactive area where depths to be evaluated can be specifi ed in inches or centimeters (cm). A general evaluation of SAR to a depth of 5 feet (150 cm) can give a realistic evaluation of soil chemical properties. yellow generally indicate lower Each mapping unit provides four However, for greater accuracy, the hazards, while blue indicates higher options for evaluating the soil evaluation should be carried out hazards. Dark blue indicates the layers. Because each soil mapping for successive 1-foot increments to a highest hazard. Maps for each depth unit includes small areas of varying minimum depth of 5 feet, or at least increment can be printed for reference. size of soils that may not be suitable 2 feet below the deepest depth of for drainage, using the worst-case the drain line. For each increment, The information contained in these scenario is important to identify soils a colored fi eld map will appear over evaluations is generalized for each that can contribute to problems with the photo base map showing the level soil series or map unit based on the subsurface drainage. of hazard related to each soil type. total composition of the map unit. The data for each map unit is populated The four choices for soil map unit A table with an interpretation and with chemical and physical property evaluation are: (1) evaluation of all average electrical conductivity (EC) information that is aggregated from soil components, (2) evaluation or SAR values accompanies the map various soil laboratories and the of dominant soil components, (3) and interpretative information. National Soil Survey Laboratory. evaluation of dominant soil condition In this evaluation, red, green and This information may change from and (4) evaluation of a weighted time to time as the database is updated. average of all soil components.

www.ag.ndsu.edu ■ 3 Figure 2. The Web Soil Survey navigation page. Note the 10 different “Quick Navigation” methods to get the parcel of land of interest. Another method is to use the mouse to repeatedly draw a rectangle around the area of interest until the fi eld of interest is highlighted.

Figure 5 (page 7) illustrates a Data embedded in the Web Soil Survey of typical soil surveys. Thus, a comparison of these four choices is based on typical characterization more detailed survey of the fi eld for a general evaluation of the 5-foot sites across the normal geographic to be drained will be useful for (150-cm) depth zone of an actual parcel range of the occurrence of a specifi c determining whether problems of land with sodium-affected subsoils. soil type. Due to natural variability, with subsurface drainage may exist. the soils in the parcel of interest may Table 4 shows a comparison of the vary from the “typical” map unit of All soils with an SAR value of greater associated soil SAR ratings with these the soil designated when the soil than 6 should be sampled for detailed evaluations. As shown in Table 4, survey was conducted. chemical characterization. A qualifi ed evaluating the soil map units on the professional soil scientist or classifi er basis of all components will give the In addition, detailed variability and should be consulted when making ratings for the most limiting soils small inclusions within a soil map these evaluations. within the map unit and provide unit are diffi cult to show at the scale for identifi cation of the highest risk (or worst-case) scenarios.

4 ■ SF-1617 Evaluation of Soils for Suitability for Tile Drainage Performance Figure 3. The land parcel can be delineated by clicking on one of the two AOI (Area of Interest) buttons (yellow arrow) on the interactive map. Selecting the left button allows you to put a rectangle around the AOI and the right button can be used for irregular-shaped parcels. Selection of the AOI allows the Web Soil Survey to access soil survey information specifi c to that parcel of land.

Table 4. A comparison of evaluation methods for soil SAR ratings based on soil chemical data in the Web Soil Survey. Web Soil Survey SAR Rating Map Unit All Dominant Dominant Weighted Average Symbol Map Unit Names Components† Component‡ Condition§ of All Components¶

I237A Fargo-Enloe silty clay loams, 0 to 1 percent slopes 8.1 0.9 0.9 0.9 I242A Ryan-Fargo silty clays, 0 to 1 percent slopes 14.1 14.1 14.1 9.0 I251A Aberdeen-Galchutt-Fargo complex, 0 to 2 percent slopes 14.1 8.1 8.1 4.5 I361F Orthents-Aquents-Highway complex, 0 to 35 Percent slopes 0.0 0.0 0.0 0.0

† All soils normally occurring in a map unit. ‡ The major soil(s) making up a map unit. § The usual state of the soil chemistry of the major soil(s) in a map unit. ¶ The average rating based on the normal relative proportions of all soils within a map unit.

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Figure 4. Accessing the evaluation data. Once the soil map is retrieved from the database, click on the Soil Data Explorer tab near the top of the page (yellow arrow No. 1). Then click on the Soil Properties and Qualities tab below the Soil Data Explorer tab (yellow arrow No. 2). From the menu to the left of the map, select Soil Chemical Properties (yellow arrow No. 3) and Sodium Adsorption Ratio (yellow arrow No. 4). This will lead to a refreshed map with sodium adsorption ratio (SAR) ratings for each soil series mapped on the parcel.

Subsurface Soil Drainage issues. Nor will it address social or performance should be subject to verifi - environmental issues or soil productivity cation by soil sampling and testing. Suitability Rating or design information. A soil drainage suitability interpretation This tool may give limitation ratings for has been incorporated into the Web Soil The suitability rating provides a multiple factors for each soil in a map- Survey. This rating evaluates all soils numerical rating on a scale of 0 to 1 ping unit. While most limiting factors in a soil mapping unit on three criteria: for each of the criteria listed above are based on soil properties that do not installation, performance and outfl ow and provide a weighted rating based change with drainage or management, quality. Table 5 illustrates the informa- on the components of a soil map unit. soil SAR and EC factors are subject to tion covered by these criteria. What the A rating near 0 indicates no limitations change as soils are drained. However, soil drainage suitability rating will not for subsurface drainage, while a rating other limitations identifi ed by using provide is a comprehensive site evaluation near to 1 is very limited. Soils with this tool may respond to modifi cations or determination of and fl ooding a rating greater than 0.15 for SAR in design and installation.

6 ■ SF-1617 Evaluation of Soils for Suitability for Tile Drainage Performance a. c. Figure 5. General evaluation of soil SAR in the 5-foot depth zone: (a) evaluation of dominant component, (b) evaluation of dominant condition, (c) evaluation of weighted average of all components and (d) evaluation of all soil components in each map unit. Note that for this fi eld, Figures 5 a, b b. d. and c are identical, but that may not be true for all land parcels. Evaluation of all components within each map unit provides the most stringent information regarding soil SAR conditions. Dark blue indicates a high degree of SAR hazard. (See Table 4 for SAR ratings.)

The soil drainage suitability rating Table 5. Criteria evaluated in subsurface drainage suitability ratings for is not designed to tell the landowner, subsurface water management in the Web Soil Survey. land manager or tile installer that a Installation Performance Outfl ow Quality Agronomic Concerns fi eld should or should not be drained. Depth to bedrock Presence of Plant establishment The rating mainly is designed to or cemented pan dense layers in soil present information that can be StabilityStability of S Soiloil permeability Pesticide and Plant growtgrowthh used in making a decision whether excavationsexcavations nutrnutrientient potentialpotential drainage is a suitable option as a land treatment. Amount of soil clay Flooding Soil cracking Soil erosion potential

Presence of stones Surface pH Physical limitations

Slope gradient Soil sodium content Pesticide and nutrient Soil gypsum content management Soil subsidence Sedimentation

www.ag.ndsu.edu ■ 7 Table 6. Interpretation of soil SAR values and subsurface Verifi cation of Soil drainage suitability ratings for suitability of soils for drainage. Properties by Soil SAR Values† Drainage Suitability Rating‡ Interpretation Sampling and Soil Testing < 6 <0.15 No limitation Table 6 provides SAR suitability 6-10 0.15-0.80 Somewhat limited ratings for soils based on the soil >10 >0.80 Very limited chemistry evaluation described above. † Based on data from Springer (1997). Once soil areas that have a moderate ‡ Based on Web Soil Survey. or severe SAR hazard are identifi ed, these areas should be sampled to a minimum depth of 6 feet in 1-foot Utilizing registered professional soil For more information, check out increments. The soils should be scientists or NRCS soil scientists can the following publications: sampled at a minimum of three assist in making decisions about Curtin, D., H. Steppuhn and F. Selles. locations within each soil map unit alternatives to subsurface drainage. 1994. Clay dispersion in relation to where an SAR hazard has been sodicity, electrolyte concentration, identifi ed. Samples from these Table 6 should be used only as and mechanical effects. Soil Sci. Soc. locations can be composited into one a guide for drainage suitability. Am. J. 58:955-962. sample for each depth increment. Dispersion of the soils under Oster, J.D., and F.W. Schroer. 1979. Infi ltra- subsurface drainage conditions tion as infl uenced by water A minimum of one composite soil depends on several factors, including quality. Soil Sci. Soc. Am. J. 43:444-447. sample should be submitted for the composition of soil minerals, soil Pearson, K.E. 2003. The basics of each fi ve acres of a soil map unit in texture, composition of shallow ground salinity and sodicity effects on soil question. Each soil depth increment water and composition of soil salts. physical properties. should be analyzed for electrical Also recognize that soils subject to Montana State Univ. Ext Ser. Fact Sheet. conductivity (EC) and SAR using dispersion may be localized or only At http://waterquality.montana.edu/docs/ standard soil saturation paste a small proportion of the soils in the methane/basics_highlight.shtml. Accessed extracts for the evaluation. This fi eld or land parcel to be drained. March 15, 2011. allows for direct comparisons with Springer, A.G. 1997. Water-dispersible clay the information contained in the Evaluating soils for subsurface and saturated Web Soil Survey database to verify drainage suitability prior to installation in relation to sodicity, salinity and soil texture. M. S. thesis. North Dakota State the suitability for subsurface drainage. can reduce the incidence of poor tile performance and unrecoverable instal- Univ., Fargo, N.D. If the soil analyses indicate that the lation costs. If soils susceptible to poor Springer, G., B.L Wienhold, J.L. SAR values are lower than the values drainage are identifi ed prior to tile Richardson and L.A. Disrud. 1999. shown in Table 6, then the soil is installation, then alternatives to Salinity and sodicity induced changes in dispersible clay and saturated likely suitable for subsurface drain- drainage can be considered and hydraulic conductivity in sulfatic age. If soils are rated unsuitable for implemented. Once soils disperse soils. Commun. Soil Science Plant tile drainage, then alternatives such due to subsurface drainage, attempt- Anal. 30(15-16):2211-2220. as leaving the soil area undrained or ing to remediate the soils to near their USDA Soil Salinity Laboratory Staff. 1954. placing the area into permanent cover original internal drainage condition is Diagnosis and improvement of saline should be considered. extremely diffi cult and costly. and alkali soils. Agriculture Handbook No. 60. U. S. Government Printing Offi ce, Washington, D.C.

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