Effective Use of on Turfgrass

This article is the second in a three-part series on quality, the first of which appeared in the November/December 1999 issue. by R. R. DUNCAN, R. N. CARRO~ and MIKE HUCK

E PROBLEM: Availability of adequate water in terms of quality TIand quantity will be the number- one issue affecting turfgrass manage- ment in the 21st century. Global demand for fresh potable water is doubling every 20 years. Irri- gated areas have increased about 1% per year worldwide during the 1990s. During the past 30 years, the popula- tion of the United States has increased 52% while total water use has in- creased 300%. Renewable water re- sources per person decreased 50% between 1960 and 1998 in the United States. Another 50% reduction is pro- jected by 2025. By 2000, 20% of all U.S. communities will experience water shortages in the form of water rationing or short-term cutoffs. Competition for potable water will force turfgrass man- agers to search for alternative - from recycled to seawater. Water is available in many different forms. Seawater (34,486 ppm ) en- compasses 96.5% of the total global water supply (Gleick, 1993). reserves total 2.5%. Ground- water, which makes up 1.7% of the total global water supply, includes 55 % saline and 45 % fresh water. A total of 30.1 % of fresh water comes from the Water is available in many different forms. The ability to irrigate a golf course with . seawater has long been a dream. This dream will soon become a reality as turfgrass- Lake water reserves (0.013% of total quality ecotypes of seashore paspalum tolerant to ocean-level salt concentrations water resources) include 0.006% of become commercially available. total saline and 0.007% of fresh water. Swamp water (0.0008% of total water The Dilemma Salinization of irrigated land occurs reserves), river flows (0.0002%), gla- Water quality and availability have when dissolved accumulate in the ciers plus permanent snow cover a dramatic influence on site-specific upper soil layers on naturally saline (1.74%), and ground ice/permafrost turfgrass management strategies, re- lands, on lands with poor drainage, in (0.022%) account for the remaining gardless of whether salt-laden effluent arid/semi-arid regions, or on lands global water reserves. (recycled water), ocean water, or blends utilizing salt-laden effluent (recycled '" Crop plants normally utilize 40-45 % of the two sources are used as the water water). The percentage of irrigated of the water applied through irrigation, source. Saltwater intrusion is a major lands affected by salinization includes with the remaining 55-60% lost as concern in coastal areas (Newport, 20-25% in the United States, 13% in runoff, deep percolation, or evapora- 1997; Todd, 1997). Water withdrawal Israel, 30-40% in Egypt, 15% in China, tion/evapotranspiration. Turfgrasses from coastal groundwater can con- and 15-20% in Australia (Gleick, 1993). are probably slightly more efficient in tribute to degradation of water and soil The use of highly saline irrigation water water use than most crop plants due to quality. Renewal time for groundwater greatly enhances the potential to de- greater canopy coverage of the soil and resources is estimated at 300 years grade soil by salinization unless definite their perennial nature. (Gleick, 1993). construction and management prac-

JANUARY/FEBRUARY 2000 11 tices are followed. Accumulation of areas on the golf course, including blended with other nonpotable water excess total salts (salinization) and roughs, surrounds, and mounds must resources, or salt-laden effluent is now (sodic soil formation) in the be managed as primary areas. feasible (Duncan and Carrow, 2000). soil is more rapid as irrigation water 4. Salts must be removed by drainage The problem of saltwater intrusion quality declines. The dilemma con- systems and be properly disposed of to into coastal aquifers that results in fronting turfgrass managers is how to prevent contamination of any potable unintentional application of seawater effectively use water of poor quality groundwater under the site and to onto golf courses, and coastal or low- without causing excessive salt prob- prevent soil salinization. land saltwater inundation from storm lems that will result in substantial 5.The cost of pumping from surges/salt deposition now can be decline in turfgrass quality and near the ocean is increased due to addressed with the most salt-tolerant performance. increasing irrigation demands (for turfgrass (Carrow and Duncan, 1998). Potential climatic changes will com- proper leaching). Minimal water lifting These extreme cases of the ultimate plicate water and salt management. is required, which offsets some of those poor water quality require serious and Possible climatic changes projected costs. diligent pre-construction, establish- globally from increasing CO2 atmo- 6. Coastal aquatic sites are impacted ment, grow-in/post establishment con- spheric levels include: (especially saltwater intrusion) and siderations for successful turfgrass • 2-5°C increase in temperature; should be carefully monitored. management. The site-specific nature • 0- to 32-inch increase in sea level; 7. Maintenance costs may be 50% of -challenged environments • Precipitation increase of 7-15%; higher than in non-salt affected areas causes the most complex and, often, • Direct solar radiation change -10% because of continuous application of most confusing situations involved in to +10%; 5-10% evapotranspiration amendments to minimize salt buildup turfgrass management. Mistakes or increase (Woodward, 1992). and corrosion damage to maintenance, omissions become readily apparent These climatic changes will signifi- irrigation, and other equipment, requir- and amplified once the grass is planted cantly affect turfgrass management in ing more frequent replacement. and the turf responds to its environ- the 21st century. Because of these 8. Highly trained turfgrass managers ment. changes, most recreational turf will are necessary because of the site- Growth rates of all turfgrasses, in- possibly be mandated to be irrigated specific complexity of the salt-related cluding seashore paspalum, are re- with nonpotable resources (California problems. duced when exposed to increasing Assembly Bill 174,Oct. 1991).Desalini- 9. Unnecessary traffic on turf should levels of salinity. Older bermudagrass zation is one option as an alternative be reduced or eliminated to (a) offset (Tifway) and creeping bentgrass culti- water resource, but cost comparisons the lack of wear recovery caused by vars (Seaside, Seaside II, SR1020, and and the volume of water produced are growth reduction resulting from salt Mariner are better choices) will tolerate key considerations (California Coastal stress and (b) avoid compacting satu- only about one-third ocean level salt, Commission, 1999). rated soils that are frequently irrigated and therefore may be suitable for use to field capacity in order to promote with some effluent and/or brackish Irrigating with Seawater leaching. sources, depending on water quality. With the availability of ocean-level, However, selected ecotypes of sea- salt-tolerant turf species, using seawater Pre-Construction Considerations shore paspalum can tolerate straight for irrigation becomes a viable option ocean water (TDS = 34,486 ppm salt, Grass Selection 1 in turfgrass management. The focus of ECw = 54 dSm- , SAR = 57.4 meq L-l, this article is to emphasize those critical As we enter the new millennium and Na = 10,556 ppm, CI = 18,980 ppm, is-sues that arise when this worst-case potable water becomes a more scarce Mg = 1,304 ppm, Ca = 420 ppm, K = water option (i.e. seawater) is selected resource, continued development of 390 ppm, S04 = 2,690 ppm, HC03 = as the irrigation source. The basic prin- salt-tolerant species (turfgrass, trees, 146 ppm). Landscape plants also must ciples are applicable to sites using salt- ornamentals, and other landscape~ be able to tolerate high total salts and laden effluent. plants) will become increasingly impor- toxic CI and Na levels. Careful planning Irrigating food crops, as as tant for all recreational landscapes, in- and proper managment are the keys to turfgrass, with seawater requires that a cluding golf courses. Research funded success when using seawater for irri- number of basic guidelines be con- by the USGA has resulted in the gation on turfgrass. sidered (Glenn et al., 1998): development of high-quality, environ- 1. Halophyte turfgrasses (salt-toler- mentally friendly and ocean level salt- Water Quality Assessment ant species such as seashore paspalum, tolerant seashore paspalum turfgrasses Monitor water quality by location saltgrass, or alkaligrass) and landscape for use on greens, tees, fairways, and and over time, especially if the source plants should be planted. roughs. This grass currently provides a is brackish or the water is obtained 2. Golf courses should be con- unique opportunity in temperate and from a well subjected to saltwater structed on sandy, well-drained coastal tropical climates to utilize alternative intrusion where the salt water retreats sites for long-term sustainability. water resources for irrigation. Addi- during wet periods or encroaches dur- 3. Water should be available at suffi- tional research and breeding efforts to ing dry periods. Intrusion of salt water cient volumes to leach salts, minimiz- improve salt tolerance of cool-season into a well head can occur abruptly ing the concentration of salts in the species (some private companies have and, consequently, regularly scheduled rootzone and preventing dry down of made this a priority) will extend alter- water quality testing will be necessary. the surface caused by evaporation and native water use to northern climates. If salt-laden effluent is used directly percolation. High leaching events are Irrigation with ocean water (34,486 or blended with seawater, quality critical, and proper irrigation schedul- ppm salt), (at salt con- should be monitored over time. Rela- ing is essential to success. All irrigated centrations < 34,000 ppm), seawater tively inexpensive electrical conduc-

12 USGA GREEN SECTION RECORD tivity meters can be easily used by turf managers for on-site monitoring of total salinity. Seawater drawn from wells may be influenced by local soil conditions, such as those exhibiting

higher bicarbonates (HC03t or from excessive levels of other components, such as or boron or extremely low pH «5.0) conditions where Al or Mn levels might be extremely high. Knowledge of water constituents and their fluctuation over time is essential for making manage- ment decisions. Commercially available, putting green quality seashore paspalum tolerates low mowing heights and ocean-level salt concentrations in the irrigation water. The Irrigation System Irrigation system design efficiency ocean water compared to non-salt 4. Application of fertilizer or other includes sprinkler head spacing for affected situations. amendments through the irrigation uniform coverage, nozzle size tailored The additional volumes of water system. to soil texture (percolation rate, e.g., needed to leach salts delivered by sea- Desalinization is one option as an fine-textured soils may require low ap- water or other poor-quality recycled alternative water resource, but cost plication rates), and individual sprin- or brackish water can require special comparisons and volume of water pro- kler head control to ensure flexible consideration when designing the duced are key considerations (Cali- scheduling. Pulse irrigation is essential hydraulic capacity of the irrigation fornia Coastal Commission, 1999). on soils with low infiltration and per- system. Pipe sizes need to be increased Corrosion of irrigation hardware colation or with poor or slow drainage to avoid excessive flow velocities that and other equipment exposed to ocean characteristics since it can be difficult cause subsequent water hammer and water also is a major concern and to effectively manage and match pre- fatiguing damage to PVC components. should be addressed within the design cipitation rates of large turf sprinklers Inadequate pipe sizing will result in a specifications. Plastic pipe and sprin- to the infiltration rates in these salt- longer window for total operating time, klers are naturally preferred where challenged soils. Pulse irrigation pro- resulting in sprinklers operating before feasible. Where steel components are" vides water to the turf at a rate up to dusk and after dawn, interfering with normally specified, epoxy coating, runoff and then stops to allow for both maintenance operations and golf high-grade stainless steel (Austenitic) infiltration/percolation, followed by play. A general rule of thumb when or ductile iron fittings on PVC mains repeated cycles. The intermittent appli- designing the irrigation system is that should be investigated for improved cation of water throughout a daily irri- no greater than an 8-hour window of longevity and economic feasibility. gation cycle via pulse irrigation pro- operation should be needed to irrigate Custom manufacturing using seawater- vides for: the golf course at maximum ET while resistant nonferrous metal blends and 1. Maximum leaching of excess salts. including the proper leaching fraction. marine or grade equip- 2. Minimal buildup of excess Na, A "dual" mainline irrigation system ment and paint also may be options for which causes soil structural breakdown to allow irrigation of salt-sensitive areas consideration. Components exposed to (sodic soil conditions). (cool-season grass putting greens, club- salty sprinkler spray (wetting and dry- 3. Minimal bicarbonate precipitation house landscape areas) with a better- ing cycles) will deteriorate more rapidly and sealing at the surface of sandy quality water also is an option. Another than those that are always submerged. soil profiles caused by light, frequent alternative is a system of multiple Items such as controller cabinets irrigation. storage lakes that allow blending of should be manufactured from stainless The number-one management re- alternative water sources for leaching. steel or plastic and be maintained in quirement of all salt-affected turfgrass Under either ofthese scenarios, reverse a relatively watertight condition to sites is leaching to remove excess salts osmosis could be incorporated into the inhibit corrosion of internal electrical or to prevent sodium and chloride system to supply water for occasional components and connections. It also is accumulation. The leaching require- leaching, blending, or management of imperative that all buried wiring splices ment (LR) is the quantity of water re- salt-sensitive areas. Any of these op- are made with the highest-quality quired to maintain a moist soil profile tions should be included in the design waterproof-type connections. Another with consistent net downward move- phase on a cost-effective basis. option would be to install a radio- ment of salts below the turfgrass root- A dual irrigation system would prove operated control system (such as zone that is over and above turf evapo- beneficial for: OSMAC from Toro and FREEDOM transpiration (ET). Turfgrass ET can be 1. Blending seawater with waste- from Rainbird) that eliminates the need high due to coastal winds or high water to dilute the total salts and high for hard wiring of a low-voltage signal temperatures, especially during estab- Na+levels (improve overall quality). loop between the computer central lishment when soil evaporation is 2. Irrigation of golf greens with control and the satellites. This type of excessive. Total saltwater needs include reduced salt-laden sources (such as system would eliminate a number of LR + ET + correction for irrigation reverse-osmosis water). additional and potentially troublesome design inefficiency. Total water use 3. Use of alternative water resources electrical connections that are prone to could average 30-50% higher using during periods of high volume leaching. failure under highly saline conditions.

JANUARY IFEBRUARY 2000 13 Highly sandy soils are very desirable soluble fertilizers) that will be needed systems, and desalinization/reverse since leaching is much easier on sands continuously and periodically at high osmosis equipment will raise ongoing compared to fine-textured soils that rates. Some of these added costs are long-term maintenance costs. have lower infiltration/percolation/ offset by reduced needs for herbicides 4. Accelerated equipment replace- drainage rates. Additionally, sandy soils and other pesticides and a less expen- ment schedules for maintenance equip- that drain more rapidly will return to sive water source. ment and course accessories are com- playable conditions in less time follow- 2. Cultivation equipment (both sur- monly required on sites with saline ing leaching and will resist compaction face and subsurface types) to maintain irrigation sources. Daily exposure to from maintenance equipment and water movement for efficient leaching salt-laden irrigation spray, exudation other traffic when wet. Continuous of salts through soils. Fine-textured water, and runoff deteriorates metal paved cart paths and cart restrictions soils will require much more aggressive components on mowing equipment, on the turf also are recommended to cultivation programs than sandy soils. utility vehicles, and course accessories minimize traffic damage from stresses The effectiveness of a cultivation such as signs, benches, and ball-wash- due to: operation is typically reduced by one- ers (much like the corrosion on auto- 1. The reduction of turf growth and half on high-Na sites and cultivation mobiles in northern climates caused recovery from wear caused by salt frequency must be increased. Both from salting and deicing highways). accumulation. deep (10-12 inches) and shallow (3-5 Undercoating and rustproofing treat- 2. Excess compaction when traffic inches) aeration practices are essential ment of undercarriages on all equip- occurs on saturated soils following for proper salt leaching. Deep-tine ment is recommended. A potable water regular leaching events. cultivators include Verti-drain, Soil source also should be used when wash- Reliever, Aerway Slicer, and Deep-drill. ing equipment after every use to slow Salt Disposal The Yeager-Twose Turf Conditioner is the corrosion process. less effective for deep cultivation (i.e. > 5. The turf manager must be well The golf course design must include 7 inches), but has excellent chemical trained in order to maintain high- plans for environmentally sound dis- injection capabilities (capable of apply- quality turf. Salt-related problems are posal of leached salts (and/or brine if ing 80-90 lbs. per 1,000 square site-specific and very complex because is used) when seawater feet at a 7-to 8-inch depth). The Hydro- of multiple environment/turf inter- is to be used for irrigation. The primary ject units also can be used to enhance actions. considerations involve: seawater irrigation percolation into the 1. Avoidance of salt accumulation soil profile. below the turfgrass rootzone in an Sand Capping and Drainage 3. Extra irrigation equipment. The increasingly concentrated form. Even- corrosive nature of the high salts in If saline-sodic soil is dredged from tually, this zone of salt accumulation ocean water will require constant an ocean bay and added as the top- will rise to the soil surface and cause monitoring and more frequent replace- soil for the turfgrass rootzone, several catastrophic injury to all plants and ment of certain components like practices are suggested to alleviate their root systems. sprinkler heads and irrigation pumps. the high total salts and excess Na 2. Prevention of or salt Injector systems can occasionally be that cause considerable soil structural seepage into a potable water source or used to treat seawater. Acidification deterioration: freshwater off-site area, or contami- (H2S0 , N-phuric acid, or urea sulfuric 1. Deep-tine (10-14 inches) aerate nation by saltwater intrusion due to 4 acid, sulfur dioxide generator) to aid in and apply 200-600 lbs. gypsum per excessive removal from the good water the formation of gypsum (CaS0 ) in the 1,000 square feet to the soil surface and source. 4 soil by reaction with surface-applied rototill into the top six inches. Higher Both considerations involve proper lime (CaC03) is one method of supply- rates may be needed for heavier clay land surface contouring and adequate ing considerable Ca2+to replace Na+on soils. deep-tile drainage lines (3-5 feet) with soil cation exchange sites (CEC). The 2. Apply an additional 200 lbs. outlets either directly into the ocean excess Na combines with the available gypsum per 1,000 square feet to the or into a carefully constructed and S04 from the acids to form Na2S04, surface and cap with two inches of impervious well or holding pond. The which then can be leached. coarse sand. Till into the top 1 or 2 34,486 ppm of total salts in seawater is Another method of supplying high inches of soil. equivalent to 2, 153lbs. of salt per 1,000 levels of Ca2+ ions to counter high Na+ 3. Cap with an additional six inches square feet per foot of seawater applied. levels in seawater is a gypsum injector of coarse sand. The more coarse the Deep coarse sands (>0.50 mm) with linked with the irrigation system. CaClz, sand (especially 0.5 to 1.0 mm range high percolation rates (>10 inches per Ca(N0 )2, or other highly soluble and none exceeding 2.0 mm), the better hour) are strongly preferred when sea- 3 amendments can be added with this the rate of percolation and the faster the water is used for irrigation. unit. Although seawater contains rela- leaching with less volume of seawater

tively low HC03- (146 ppm), water that irrigation. Coarse sand in the 1.0 to 2.0 Long-Term Maintenance Costs is pumped from ground wells near the mm range should probably not exceed Seawater irrigation requires pro- ocean can occasionally contain levels 10-20% (by volume) of the total coarse active management to minimize the exceeding 550 ppm, which would sand to minimize damage to golf clubs constant threat of saline-sodic soil benefit from acidification to remove the and maintenance equipment. conditions and their resulting impact excess bicarbonates. This removal If fine-textured soils that are high on turfgrass performance. Increased releases the Ca and Mg in the water to in silt and clay content have low infil- budgeting needs include: counteract the excessive Na in the tration and percolation rates, appli- 1. Extra chemicals (gypsum, acids, seawater. Additional lakes, pumps, and cation of a 6- to 12-inch coarse sand lime, micronutrient fertilizers, highly piping for blending, dual irrigation layer (cap) over the existing soil will

14 USGA GREEN SECTION RECORD enhance the leaching effectiveness in the rootzone and help maintain water infiltration by reducing surface soil compaction. Incorporating 4-5 % or- ganic matter into the coarse sand prior to capping will (a) provide improved water-holding capacity, (b) help main- tain a moist soil profile for a longer time frame compared to straight sand with no organic matter, and (c) minimize or slow down upward movement of salts concentrated below the rootzone when surface evaporation demands exceed seawater application rates. Wind + high temperatures + exposed sandy surfaces during establishment and early grow-in can place very high evaporative demands on the overall turfgrass system. Heavy leaching at night to keep the salts moving down- ward followed by periodic seawater applications during the heat of the day in an effort to maintain uniform soil moisture and prevent upward move- ment of concentrated salts are the key irrigation maintenance practices for successful establishment and grow-in of turf with seawater irrigation. One additional alternative - a fair- way system with full drainage - could be considered. The concept involves creating the world's largest USGA green by letting the subsoil seal with excess Na+(creating a lake bottom) and installing a subsurface drainage system below the sand cap. The drainage system allows collection and disposal of the salt -laden drainage water, if engineered correctly, and also protects any potable groundwater or aquifers in the immediate area. Construction As we enter the new millennium and fresh water becomes increasingly more scarce, alternative water supplies and salt-tolerant turfgrasses for golf become a much better costs are initially higher, but savings in option than the "other" alternative. deep aeration, gypsum applications, and associated labor to perform these maintenance operations could. con- main drains and occasional drain growth rate will be reduced, prolonging ceivably pay for the drainage system basins, 30-foot lateral spacing would the grow-in period. Additionally, salt over a six-year period. cost about $997,000 and 20-foot lateral accumulation on the soil surface occurs For example, approximately 2,378 spacing would cost about $1,432,800 very rapidly when seawater is used for lbs. gypsum (23% Ca) per 1,000 square initially for the fairway drainage. If the irrigation unless appropriate manage- feet must be applied for every 12 inches gypsum rates could be reduced to 50% ment practices are used. Proper man- of seawater irrigation to counter the for treating the sand cap (instead of agement techniques can minimize the high Na+concentration. In deep sands keeping the subsoil draining) and utili- need for an expensive replanting. Fac- with < 2-3 % silt and clay, the gypsum zing subsurface drainage, the system tors to consider~nclude: rate can be reduced by 50-70%. How- could pay for itself relatively quickly. 1. Reduction of total salts for estab- ever, sand-capped sites still require the With heavy rains from monsoons, hur- lishment. Seawater has a total salinity 1 higher gypsum rates to maintain non- ricanes, or tropical storms, this drain- level of ECw = 54 dSm- • Total salts will sodic conditions in the subsoil. For age system would be extremely bene- only be reduced below 54 dSm-1 (a) practical purposes, assume the golf ficial for rapid removal of excess water. after a heavy rainfall or prolonged course covers 100 acres and the gypsum rainy period, (b) by use of better-quality costs $100 per ton, or about $2,178 per Establishment water sources (effluent, brackish, month (at 100 lbs. per 1,000 square feet All turfgrass and landscape plants are reverse-osmosis water), or (c) by blend- per month, or about $5,180 per acre- more sensitive to high-salt problems ing with lower salt-containing water foot of seawater). Assuming a 7,000- during initial root formation and early sources. yard course and $6.00 per linear foot establishment. Besides the high -salt 2. Alleviation of Na-induced soil for solid perforated pipe including impact on the root system, the turfgrass physical problems in the surface zone.

JANUARY/FEBRUARY 2000 15 Aggressive deep and shallow aeration, daytime demands when using seawater. establishment. Soil test analysis will gypsum application, cultivation, top- On sands, the nighttime leaching event reveal the need for additional nutrients dressing, and leaching are key manage- should be sufficient to move surface in conjunction with nutrients supplied ment options. Gypsum applications salts (i.e. the wetting front in the soil by the seawater. High leaching events should always be made immediately profile) to at least 12 inches and on can deplete micronutrient (Fe, Mn) following aeration to avoid creating a fine-textured soils to at least 16-20 levels, and careful monitoring is neces- Na+-affected layer deeper in the soil inches depth. This will minimize capil- sary on a continuous basis. Potassium, profile. lary rise of more concentrated salts Ca, and Mg also are subject to leaching 3. Maintenance of a uniformly moist back to the surface and into the turf- losses and should be monitored closely. soil profile. Preventing the soil surface grass rhizosphere. This heavy leaching 1 Post- Establishment/Mature Turf ECe from rising above 54 dSm- when event may be done over two nights on seawater is the sole source of irrigation fine-textured soils if percolation rates The use of seawater for turfgrass water will require: are low. Seawater irrigation schedul- irrigation produces two very important (a) Keeping the salts moving - a ing during the day should be frequent results that significantly impact man- continuous program of supplying suf- enough to maintain a continuous and agement strategies: ficient water volume is necessary to uniformly moist soil profile with mini- 1. Seawater supplies additional maintain net downward movement of mal surface drying. A monthly gypsum nutrients that require adjustment in salts away from the rootzone and soil application of 100-200 lbs. per 1,000 fertilization protocols, and chemicals surface, and to prevent them from square feet can be surface-applied as a that are applied to replace excess Na+ rising back up by capillary/absorptive sodic-soil preventative strategy when on soil CEC sites necessitate additional water movement. using seawater for irrigation. nutritional adjustments (Table 1). (b) Maintaining moist soil profile 4. Adequate initial fertilization and • All ions in Table 1 contribute to conditions between irrigation events careful monitoring of micronutrients overall high total salts, with Na+ and so that salts do not concentrate in the with continuous leaching events. A CI- ions contributing the most salts soil or rise by capillary action spoon-feeding approach (frequent because of total quantity. As long as from below the surface zone. If the applications, 110 to 12rates) is necessary adequate irrigation water is applied, 1 salts move down at ECe = 54 dSm- on seawater-irrigated sites, with total chloride is easily leached. Excess and concentrate, high evaporation in annual fertilizer nutrients applied at chloride can detrimentally affect nitrate sandy soils can bring the salts back to 1.5 to 2.0 times that used on areas irri- uptake. 1 the surface at ECe > 54 dSm- and kill gated with non-salt-Iaden water. While • Excess Na+ will rapidly cause a the young turf seedlings. higher annual rates of fertilizer are severe sodic-soil condition (soil struc- Light, frequent seawater irrigation at required, the rates per application are tural deterioration) unless high quan- establishment or on mature turf with- similar to non -salt-affected sites, but the tities of Ca+2ions are added to replace out adequate leaching will result in frequency is greater. Use of highly Na+ on the CEC sites and sufficient rapid surface resalinization and subse- soluble fertilizers and fertigation water is added to leach the ion away quently lead to turfgrass failure even through a well-designed irrigation from the turfgrass root system. A sodic- with the most tolerant turfgrass culti- system is very beneficial. soil situation is much more serious on vars. Scheduling high leaching events Adequate phosphorus (2-3 lbs. P20S fine-textured soils than on sands. At at night will minimize competition per 1,000 square feet) should be applied least 547 lbs. elemental Ca+2per 1,000 from wind and the high evaporative to the surface at planting to promote square feet or 2,378 lbs. gypsum (23 % Ca) per 1,000 square feet must be applied for every 12 inches of seawater irrigation to counter the high Na+ con- centration. In deep sands with < 2-3 % silt and clay, the gypsum rate can be reduced by 50-70%. Sand-capped sites will still require the higher gypsum rates to maintain non-sodic conditions in the underlying soil, unless a complete subsurface drainage system has been included (discussed in sand-capping section) . • Additional highly soluble Ca

sources could include CaCl2 or

Ca(N03h, which could be applied

through injector systems. Lime (CaC03) can be applied to the soil to react with S04-2in the seawater to form gypsum. Approximately 170 lbs. lime per 1,000 square feet per 12 inches seawater irrigation is needed to react with 168 lbs. SO/ in the seawater. • A 3:1 to 8:1 ratio of Ca:Mg is pre- As the bermudagrass succumbs to high salt levels, seashore paspalum (lighter color) ferred in irrigation water. Ca deficiency fills in the putting green. may occur below 3:1 and Mg deficiency

16 USGA GREEN SECTION RECORD References Table 1 California Assembly Bill 174 (October) Quantity of nutrients applied with typical seawater irrigation 1991.Water resources - reclaimed water- nonpotable use. In Statutes of 1991-1992 Ibs.ll,OOO sq. ft. per Regular Session. State of California Legis- Ion 12 inches seawater meq VI ppm 0/0 of Cations lative Counsel's Digest. Chapter 553, p. Ca+2 26.2 21.0 420 3.5 2321-2322. Mg+2 81.4 106.8 1,304 17.9 California Coastal Commission. 1999. Sea- K+ water desalinization in California. Website: 24.3 9.9 310 0.8 www.ceres.ca.gov Icoastalcomml desalrpt Na+ 659 458.8 10,556 76.9 Idkeyfact. html. S04.2 168 56.0 2,690 Carrow, R. N., and R. R. Duncan. 1998. CI' 1,185 534.6 18,980 Salt-affected tur/grass sites: assessment and management. Ann Arbor Press. HC03' 9 2.4 146 Chelsea, Mich.

C03 <1 Duncan, R. R., and R. N. Carrow. 2000. N 11.5 Seashore paspalum: the environmental turfgrass. Ann Arbor Press. Chelsea, Mich. P 0.06 (Projected publication by January 2000). Mo 0.01 Gleick, P. H., ed. 1993. Water in Crisis: a Fe 0.002 guide to the world's freshwater resources. Oxford Univ. Press, Oxford, UK. Mn 0.0002 Glenn, E. P., J. J. Brown, and J. W O'Leary. 1998. Irrigating crops with seawater. Scien- tific American 279(2):76-81. above 8:1. The 1:5 ratio of these two applied at the recommended rate, but elements in seawater is usually not a 1.5-2.0 times more frequently. Herbert, F. 1999. Principles of water move- ment. Sports Turf 15(2):24-28. problem since large quantities of Ca are Summary applied as an amendment to replace Iyengar, E.R.R., and M. P. Ready. 1994. Crop Seawater irrigation on turfgrass is Na+when using seawater for irrigation. response to salt stress: seawater applica- If feasible with: tion and prospects, p. 183-201. In M. extra Mg is needed, dolomitic lime Pessaraki (ed.) Handbook of Plant and can be used as a slow-release Mg • Highly salt-tolerant turf species. • Coarse, sandy soil profiles. Crop Stress. Marcel Deklar Inc. New York, source, or a soluble Mg source can be N.Y. applied by fertilization. • Irrigation strategies that keep salts moving with regular leaching events Newport, B. P. 1997.Saltwater intrusion in • Even though 24.3 lbs. K is applied and keep the soil profile uniformly the United States. EPA-600/8-77-011. per 1,000 square feet per 12 inches sea- water irrigation, high N a+suppresses moist to minimize concentrated salts Todd, D. K. 1997.Salt water and its control. from rising into the rootzone. Water Works Assoc. 66(3). K+ uptake. A routine spoon-feeding • Good surface and subsurface drain- Woodward, F. I. (ed.). 1992. Global program with KN03 or K2S04is recom- age design. climatic change; the ecological conse- mended. On sand-capped areas or quences. Academic Press. London, UK. well-drained deep sands, adding 5% • Environmentally safe disposal of excess salts. by weight of medium to coarse zeolite (0.25-1.00 mm diameter) will enhance • Careful nutrient management and continuous monitoring. selective retention of K+ions. RONNY R. DUNCAN, Ph.D., is professor 2. High leaching requirements will • The entire course must receive of tUrfgrass breeding and stress physiology, high-level management. Crop &> Soil Sciences Department, Univer- enhance the leaching of all nutrients. sity of Georgia, Griffin. Research empha- • N-P-K fertilizers should be applied Pros for Using Seawater Irrigation sis is on developing tUrfgrasses with mul- in a spoon-feeding approach at 1.5 to • Non-interruptible supply of irriga- tiple environmental, soil, and man-made 2.0 times annual rates (compared to tion water during shortages/ droughts/ stress tolerance, as well as development sites with good-quality water). rationing. of environmentally sound management • Slow-release fertilizers applied fre- • Reduced water costs when com- practices. quently in ~o to lIb. per 1,000 square pared to "purchased" potable or re- ROBERT N. CARROW; Ph.D., is professor feet per application increments can be cycled water. of tur/grass stress physiology and soil used as the base fertilization with ferti- • Reduced pumping costs compared stresses, Crop &> Soil Sciences Department, gation of water-soluble sources used to similar quality brackish wells. University of Georgia, Griffin. Research to supplement turfgrass nutrition. Spot emphasis is on turfgrasses as affected by fertilization of wear/traffic areas with Cons for Using Seawater Irrigation environmental, traffic, and soil physical! granular, quick-release, soluble fertil- • Higher ongoing maintenance costs: chemical stresses. izers may be necessary. cultivation (labor, replacement tines, MIKE HUCK is an agronomist with the • The micro nutrients Fe and Mn equipment repairs), amendments, equip- USGA Green Section, Southwest Region, may require extra foliar applications at ment replacement (undercoatings), where everyday water shortages make alternative water supplies a current issue. ) 0.025 Fe and 0.013 lbs. Mn per 1,000 salt/brine/ drainage disposal. He resides in the coastal community of square feet every two to three weeks. • Higher construction costs: sand Dana Point, California, near what he now Additional granular applications may capping, additional drainage, enhanced views as potentially one of the largest be needed several times per year. A irrigation systems, reverse-osmosis irrigation reservoirs in the world - the good micronutrient fertilizer should be equipment. Pacific Ocean!

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