SEAISLE 1 IRRIGATION GUIDELINES

Leaching
Increase applied water volume by 12.5% for each 640 ppm rise in total dissolved salts (TDS) in the irrigation water to minimize salt accumulation
Net downward leaching should be sufficient to maintain salt accumulation zones at least 12-16 inches deep on sandy soils and 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 = 2153 lbs salt/1000 sq. ft./foot of seawater applied.
Extensive and regularly scheduled aeration (cultivation) at depths down to 12 inches on sandy soils and 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.
547 lb. elemental Ca⁺²/1000 sq. ft or 2378 lbs. gypsum (23% Ca content)/1000 sq. ft must be added for every 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.
70 lbs. CaCO₃ (lime)/1000 sq. ft/12 inches seawater irrigation must be added to react with 168 lbs SO₄^-2 added by the seawater (for every 3 lbs. elemental S or 9.1 lbs. SO₄^-2, 3.8 lbs. Ca⁺² will remove the S through gypsum formation).
High Cl (18,980 ppm) suppresses nitrate uptake. Use soluble NO₃^-2 fertilizer 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 2 - 3 lbs/1000 sq. ft/yr due to the dissolved nitrates in the water.
Rates can vary from 1/2 inch (13 mm) daily with good percolation to 7 " (175 mm) 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 0.5 - 1.0 inch daily (very poor quality, high total salts/bicarbonates) to 1 inch weekly (for good quality water).
Potable Water
Establishment
•Keep sprigs/sod moist for 2-3 weeks after establishment.
•Apply irrigation water each time fertilizer 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 1 inch weekly to 1 inch biweekly, depending on soil conditions and climate.
•Scale back an irrigation frequency during the fall months to force roots (rhizomes) deeper and to improve winterhardiness.
•In arid regions, maintain field capacity (-3 bars) during the winter months to minimize cold temperature injury.