Bermudagrass fairway responses to various combinations of a soil surfactant and nitrogen

Abstract

Surfactants are commonly employed in sand‐based turfgrass systems to address soil water repellency, which often results in the formation of preferential flow channels leading to non‐uniform wetting patterns. While the influence of soil moisture on nutrient dynamics is well documented, the potential of surfactants to improve N uptake remains poorly understood. A 2‐year study was conducted on ‘Celebration’ bermudagrass [Cynodon dactylon (L.)] fairway to better understand the interaction between fertility programs (296 or 586 kg N ha−1 year−1 from ammonium sulfate and 564 kg N ha−1 year−1 primarily from a controlled‐release N fertilizer) and surfactant rate and frequency (3.2 L ha−1 every 14 or 28 days, or at 6.4 L ha−1 every 28 days) on turfgrass performance, leaf N content, and soil moisture. Overall, no significant interaction was observed between surfactant treatment and fertility program. During the dry season (November to May), fertility programs influenced turfgrass performance parameters with higher N rates consistently leading to improvements in visual quality, normalized difference vegetation index, percent green cover, and dark green color index; however, no differences were observed during the rainy season (June to October). Surfactants showed no effect on turfgrass performance but led to minimal increase in leaf N content from 3.72% to 3.85%. All surfactant treatments reduced water drop penetration time at 0 cm. Moreover, surfactant treatments applied every 28 days regardless of the rate exhibited a higher volumetric water content compared to those applied every 14 days. Surfactant applications might not be an economically feasible strategy to improve leaf N content in South Florida well‐watered bermudagrass fairways.