Surfactant Coated Seeds Improve Biomass of Turf in Hydrophobic Sand

Hydrophobic soils can cause many problems for turf growth. Soil surfactants have been known to improve seed germination and growth in hydrophobic soils by enhancing water movement through the soil profile, thus increasing water availability to the seeds.  In previous research, surfactant coated seeds have increased soil volumetric water content and improved seed germination under severe environmental stress. A greenhouse study was conducted in Paulsboro, NJ, USA to determine if surfactant treated perennial ryegrass seeds improved turfgrass growth in a hydrophobic soil. Perennial ryegrass seeds were coated with a high (HSC) and low rate (LSC) of surfactant and placed in pots containing either a laboratory created hydrophobic sand with a contact angle of 103.1° or a standard hydrophilic greens grade sand with a contact angle of 33.4°. Surfactant coated seeds were seeded at a rate equivalent to 8 lb/1000 ft². The pots received 0.5”(cm) of water upon being placed in the greenhouse and thereafter 0.25”(cm) of water per day which equals 1.75”(cm) of irrigation per week. In the hydrophobic sand, HSC resulted in turf with a statistically significant higher biomass when compared to untreated seed LSC did not yield any significant difference from the uncoated seed. In the hydrophilic greens grade sand, treatment differences were not significant. When water repellency was evaluated, it was observed that the HSC, and to a lesser extent LSC reduced soil hydrophobicity in the top inch of the soil. This study indicates that HSC can lead to improved biomass of turf in a hydrophobic sand and suggests that both surfactant treatments can reduce soil hydrophobicity in the upper soil profile.