Soil Surfactant Effects On Soil Moisture Distribution and Wilting Resistance in Creeping Bentgrass Sand-Based Root Zones.

Uniform absorption and infiltration of irrigation or rainfall on sand-based putting greens promotes creeping bentgrass (Agrostis stolonifera L.) health and reduces site-specific maintenance. However, variable accumulation of thatch and mat organic layers often results in development of water-repellant areas of non-uniform moisture absorption. Soil surfactants are often employed in various combinations by golf course superintendents to relieve water-repellency and promote water infiltration. This study was designed to determine the effects of three commercially-available soil surfactants on the within-plot distribution of soil moisture (SM) and wilting resistance. Four replications of four treatments arranged in randomized complete blocks were tested on a ‘Penneagle’ green (yr 1) and a ‘Penn A4’ green (yr 2). Treatment one consisted of Cascade Plus™ (a blend of block-copolymers and ethoxylated alcohols) applied on May 15 at 25 L ha^-1 followed 60 days later with Magnus™ (a blend of ethylene oxides and propylene oxides) at 13 L ha^-1. Magnus was then re-applied monthly until September 15. Treatment two was Magnus at 13 L ha^-1 monthly. Treatment three was Revolution™ (a C₁-C₄ alkyl ether of methyl oxirane-oxirane copolymers) at 19 L ha^-1 monthly. A Theta probe meter was used to measure bi-weekly SM at 18 equidistant locations within each plot in the 0 to 4 cm layer. SigmaScan software was used to make color graphs to represent within-plot SM distribution. In June no treatment differences in SM or wilting resistance were detected. By the end of July all three surfactant treatments had significantly higher SM and close to 30% less visual wilting, with similar trends persisting through August. SigmaScan graphics were an excellent way to illustrate development or not of localized dry spots. Abundant September rainfall resulted in more uniform re-wetting of the rootzone and recovery of turfgrass quality due to all three surfactant treatments relative to the untreated.