SEA ISLE 1 MANAGEMENT section

GOLF MANAGEMENT - Irrigation

LEACHING

Increase applied water volume by 12.5% for each 640 ppm rise in total dissolved salts (TDS) in the irrigation water to minimise salt accumulation. Net downward leaching should be sufficient to maintain salt accumulation zones at least 30 - 40 cm (12-16 inches) deep on sandy soils and 40 - 60cm (16-24 inches) deep on fine textured soils. If the salt accumulation zone is located at shallower depths, salts will rise through capillary action to the turf rootzone within 2-3 days during extremely hot and prolonged dry windy conditions.

SEAWATER

Must use holophytic turf species like SeaIsle 1 (seashore paspalum, alkaligrass). Most feasible on sandy, well-drained coastal sites. Irrigation scheduling must consistently provide net downward leaching volumes to prevent concentration of salts in the turf rootzone or near the surface. Typical sea water has: Ecw = 54 dSm-1 TDS = 34,486 ppm SAR = 57.4 . RSC = <0 Na = 10,556 ppm Cl = 18,980 ppm HCO3 = 146 ppm Ca = 420 ppm Mg = 1,304 ppm K = 390 ppm SO4 = 2,690 ppm Leaching requirement (LR) = Evapotraspiration (ET) + correction for design efficiency. 15-20% more water may be needed for leaching vs. the turf ET demands. Total salts applied with seawater irrigation = 1000kg per 100m2 (2153 lbs salt/1000 sq. ft./foot) of seawater applied. Extensive and regularly scheduled aeration (cultivation) at depths down to 30cm (12 inches) on sandy soils and 40cm (16 inches) on fine-textured soils will be needed. P and K applications will be 1.5 - 2.0 times higher than on non-salt affected sites due to high leaching events. 266kg per 100m2 (547 lb.) elemental Ca+2/100m2 (1000 sq. ft) or 116kg (2378 lbs.) gypsum (23% Ca content)/100m2 (1000 sq. ft) must be added for every 25mm (12 inches) seawater irrigation to provide sufficient Ca+2 ions to replace excess Na+ on the CEC sites so that the Na can be leached. 35kg (70 lbs.) CaCO3 (lime)/100m2 (1000 sq. ft/12 inches) seawater irrigation must be added to react with 82kg (168 lbs) SO4-2 added by the seawater (for every 1.5kg (3 lbs.) elemental S or 4.5kg (9.1 lbs.) SO4-2, 2kg (3.8 lbs.) Ca+2 will remove the S through gypsum formation). High Cl (18,980 ppm) suppresses nitrate uptake. Use soluble NO3-2 fertiliser sources and spoon-feed at 10-25% above annual rates. Maintain Mg+2 concentrations at 10-20% on the soil CEC sites. Apply Fe + Mn in a 3:1 ratio, especially if the pH>8.0, and 1.5 - 2 times more frequently than on non-salt affected sites. N fertility amounts can be reduced to 1 - 1.5kg per 100m2/yr (2 - 3 lbs/1000 sq. ft/yr) due to the dissolved nitrates in the water. Rates can vary from 13mm (1/2 inch) daily with good percolation to 175mm (7 inches) weekly depending on site-specific constraints.

EFFLUENT

Wastewater treatment is designed to remove solids, decrease organic matter, and disinfect. The process does not deal with inorganic salt levels or extraction of nutrients or heavy metals. Your fertility program must be adjusted accordingly. Total salinity of municipal wastewater can increase threefold from the potable initial source to the final effluent discharge. The SAR may increase 5 - 10X. The final effluent discharge. The SAR may increase 5 - 10X. Savings from reclaimed water use may be offset by increases in soil amendments, water treatment, cultivation events, and retrofitting of irrigation equipment. Negotiations on the price for effluent water should be tied to the quality of that water and its future impact on soil type, plant species, irrigation system efficiency, and climate. Seasonal water quality fluctuations are possible. The salinity effect is site specific. Avoid salt - based amendments in salinity - affected sites. Good surface/subsurface drainage is essential. Monitor Ca, Mg, Mn, P, and K soil and water concentrations regularly, since these nutrients may be leached out before the turf roots can absorb them. Irrigation rates might vary from 12mm - 25mm (0.5 - 1.0 inch) daily (very poor quality, high total salts/bicarbonates) to 25mm (1 inch) weekly (for good quality water).

POTTABLE WATER

ESTABLISHMENT - Keep sprigs/sod moist for 2-3 weeks after establishment. - Apply irrigation water each time fertiliser treatments are made. - Gradually transition the irrigation schedule from short duration, frequent   events to longer intervals between applications and a longer duration during   each application in order to force the roots deeper into the soil profile. LONG TERM MAINTENANCE - Rates can vary from 25mm (1 inch) weekly to 25mm (1 inch) biweekly,   depending on soil conditions and climate. - Scale back an irrigation frequency during the cooler months to force roots   (rhizomes) deeper and to improve winterhardiness. - In arid regions, maintain field capacity (-3 bars) during the winter months to   minimise cold temperature injury.

IRRIGATION SUMMARY
Because Seashore Paspalum is very tolerant of poor water quality, it can be irrigated with recycled water or water subject to salt-water intrusion. However, during the establishment period, it is best to irrigate with fresh water. Due to the tolerance of Seaisle Paspalum to periods of drought, irrigation is recommended on an as-needed basis.
If signs of water deficit are present (rolling of leaf blades, wilting, foot imprints that remain on the lawn after walking on it) apply 15mm - 20mm (1/2 to 3/4 inch) of irrigation to the entire lawn. Do not apply smaller volumes of water more frequently because it will not encourage root growth.