SEAISLE 1 FERTILITY RECOMMENDATIONS

Establishment
Paspalum absorbs very little N during the first month after planting. The grass prioritizes root development. Medium to high levels of P and K are essential for rhizosphere development, especially in salt-affected environments. Basic fertilizers with ratios of 1:2:3 (N:P:K) or 1:3:4 are adequate during this period. Rates of 0.33-0.50 lbs./1000 sq. ft. biweekly for the first month are adequate if P and K soil levels are medium to high.
Grow - In
Normal grow-in from sprig planting is 2-3 months, depending on sprig volume and water quality. An aggressive "bermudagrass fertility program" will escalate the grow-in.
•About 4 weeks after planting when stolons become visible from the initial sprigs, a complete fertilizer (i.e., 2:1:3, 1:1:2, 1:2:2, or 1:1:1 N-P-K) should be applied at 1 lb./1000 sq. ft. Soil temperatures should be >55F (12.8C) and pH >5.5 for maximum conversion of NH₄++ to NO₃^-.
•Repeat fertilizer applications every 2-3 weeks until grow-in is 90% complete.
•Enhance grow-in by verticutting or slicing, beginning at weeks 5 or 6. Apply *-1 lb./1000 sq.ft. (2.4-4.8 g/ sq. m) of a highly soluble nitrate source (i.e., Ca (NO₃)₂ and irrigate. Repeat on 14-day cycles, verticutting in different directions each time.
•If the site is sodded, fertilization is the same as for the initial stolon establishment and for the second treatment at 4 weeks.
•If salt-laden water is used for irrigation, higher than normal levels of P and K plus micronutrients may be needed due to high leaching volumes. Using highly soluble nitrate sources can also be beneficial.
Mature Turf
The Seashore paspalums developed nutrient uptake and utilization mechanisms which provide functional growth and development under very low nutrient availability and severe nutrient imbalance situations. In general, SeaIsle 1 has lower nutrient requirements and a higher efficiency uptake system than bermudagrass or other warm season grasses. Adjust the ferility program to account for nutrients supplied by the irrigation water.
Nitrogen
•Paspalum will not take up NH4⁺ Nitrogen or urea Nitrogen directly. These compounds must be transformed to NO_3- Nitrogen prior to paspalum uptake (soil temperature > 55F or 12.8C and pH>5.5).
•If the soil pH <5.5, a lime addition can enhance microbial conversion of NH₄⁺ Nitrogen or urea Nitrogen to NO_3- Nitrogen.
•Fertilization schedules for paspalum are essentially a cool-season grass regimen. For salt-affected sites with high leaching needs, use the higher rate. For non-salt- affected sites, use the low rate. Fields that are frequently used will require more frequent spoon feeding applications to enhance recovery.
•Moderate amounts (0.50-1.0 lb./1000 sq. ft. or 0.25-0.49 kg N/100 sq. m) in the Spring and Fall months.
•Minimal monthly amounts (0.33-0.66 lb. N/1000 sq. ft. or 0.16-0.32 kg N/100 sq. m) during the high heat times of summer.
•Optimum annual N rates range from 2-4 lb. actual N/1000 sq.ft. (0.98-1.96 kg/1000 sq. m2). Compared to hybrid bermudagrasses, this amounts to 50 - 60% less N fertilizer annually in many environments..
•Avoid high N rates going into winter months to minimize succulence and predisposition to cold temperature injury. Early to mid-fall applications can range from 0.50 -1.0 lb./1000 sq. ft./month.
•If paspalum is overseeded with a cool season grass in the Fall, avoid high N applications until the paspalum is completely dormant, otherwise the paspalum may remain vigorous with a high growth rate and become more succulent.
•Balance quick release N sources (rapid uptake, enhanced recovery from injury) with slow release sources in a spoon-feeding approach.
•Balanced fertilizers (i.e., 10-10-10, or 19-19-19, N-P-K) can be used in 0.25-1.0 lb./1000 sq. ft. increments monthly from March to June and September to November in the northern hemisphere.
•Excess chloride in irrigation water can suppress the uptake of N
•N:K₂O ratios of 1:1.5 to 1:2.0 should be maintained.
Potassium
•Sufficient K must be supplied to paspalum on a regular schedule. Avoid exceptionally low levels in the soil. Potassium is essential for wear tolerance and stress tolerance, especially salinity/salt tolerance.
•In salt-challenged environments, excess Na can suppress K uptake. High volume leaching to enhance net downward movement of salts will deplete the soil of K - it is one of the most mobile nutrients.
•At least 3 - 8% K should be maintained on soil CEC sites.
•On salt-affected fine-textured soils, 1-2 lbs. K₂O/1000 sq.ft. (0.41 - 0.82 kg K/100 sq, m) may be needed every 2 - 4 weeks
•Apply K at 1.5 - 2.0 times the N rate (i.e., N:K₂O ratios of 1:1.5 to 1:2.0 or N:K ratios of 1:1.25 to 1:1.66).
•At least 2 - 3 weeks prior to frost, apply K at 2 - 3 lbs./1000sq. ft. (0-0-60) or 4 - lbs./1000sq. ft. (0-0-39) to enhance fall color retention, cold temperature hardening, turf density, root growth, and winter hardiness.
•K levels should be maintained at high levels all year, especially when poor quality effluent is used for irrigation.
Phosphorus
•Moderate to high levels of P should be available during establishment and grow-in. P enhances root system development.
•P should be applied at a minimum of 1 lb. P₂ O₅/1000 sq. ft. (0.22 kg P/100 sq. m) during early Spring. Annual applications on mostsites should total at least 2.0 lb. P₂ O₅/1000q. ft. (early Spring, early Summer, late Summer, prior to Fall overseeding).
•On salt-affected sites when constant leaching is used to flush excess salts downward and away from the root system:
•Increase annual rates by 25 - 50% to adjust for leaching losses.
•Light, frequent applications (3 - 6 applications annually).
Iron
•Paspalum responds to Fe amendments and rates of * - 1 lb./1000 sq. ft./application on a monthly basis should be supplied during the growing season.
Micronutrients
•In salt-challenged environments with high leaching rates, Mn, Ca, Mg, and Fe should be closely monitored for deficiencies. In non-salt affected environments, paspalum may need applications of Na as a micronutrient (rock salt, Na-based broad spectrum micronutrient sources) when using potable water.