Effects of Revolution on soil wetting, turf performance and nitrogen efficiency of a fairway prone to soil water repellency

This study reports on the effects of applications of the surfactant Revolution on soil wetting and turf performance of fairway 10 of the Rosendaelsche Golfclub, located near Arnhem, The Netherlands. In addition, the influence of Revolution on soil water repellency and the nitrogen contents in grass leaves, roots and upper 18 cm of the soil profile was investigated. The sandy soil of the fairway exhibits a water repellent behavior resulting in a lot of localized dry spots and poor turf quality, especially during dry periods in spring and summer. The influence of the treatments on the wetting of the soil was studied by measuring the volumetric water content with a hand-held Time Domain Reflectometry (TDR) probe. Actual water repellency was assessed by putting water drops at regular distances along soil cores which were taken to a depth of 25 cm with a small, 1.5 cm diameter auger. The 4 plots treated with Revolution had overall higher soil water contents, less water repellency and a better grass performance than the 4 untreated plots. The application of Revolution had no evident influence upon the total nitrogen concentration in the leaves and roots of the grass vegetation. However, the mean amounts of total nitrogen in the grass leaves from the Revolution treated plots were respectively, 27.7% and 11% higher than in those from the untreated plots on 9 July and 15 August. The higher amounts are due to the larger amounts of plant tissue present on the columns sampled from the treated plots. The mean concentrations N-(NO3+NO2) in the topsoil samples from the treated plots were on 9 July 29.3% and on 15 August 54.5% higher in comparison with the untreated plots. The mean concentration N- NH4 was in the topsoil samples from the treated plot 27.8% higher than from the untreated plots on 15 August. Since microbial mediated N mineralization is affected by moisture content, the higher N concentrations in the soil are thought to be related to the higher and more homogeneous moisture levels in the treated versus untreated plots. Applications of the soil surfactant Revolution resulted in dramatically improved soil wetting and turf performance. In addition to improved moisture availability, the better turf performance is likely affected by the increased plant available N in the soil which resulted from the more desirable and uniform moisture levels. These results are of interest for management of turfgrass with lower water and fertilizer inputs.