Soil surfactants applied with 15N labeled urea increases bermudagrass uptake of nitrogen and reduces nitrogen leaching

Background: Increasing nitrogen (N) plant uptake efficiency may result in better plant quality and growth, less N susceptible to leaching and potential contamination to surrounding environments. Soil surfactants have been documented to increase water infiltration and enhance water uniformity throughout the soil profile. Thus, applying a surfactant may increase N uptake and use efficiency. Methods: To investigate this theory, four treatments were applied to bermudagrass grown in leaching columns filled with one of three soils (sand, sandy loam, and sandy clay loam): (1) 10% alkoxylated polyols and 7% of glucoethers surfactant with 15N labeled urea, (2) 10% oleic acid esters of block copolymer surfactant with 15N labeled urea, (3) water with 15N labeled urea, and (4) water without 15N labeled urea. Ambient 15N was determined by the no surfactant and no urea treatment. Each treatment combination was replicated five times and the greenhouse experiment was repeated. Bermudagrass quality and density, leachate volume, and volumetric water content were determined over a 28d period following application. Determination of 15N recovery in plant, soil, and leachate occurred at experiment termination. Results: Applying either surfactant with urea resulted in significantly higher soil volumetric water content (in sandy loam and sandy clay loam soils) and higher bermudagrass clipping yield (in all soils) than urea. Surfactants applied with urea decreased percent 15N recovery in leachate from sand by 37–46%, increased percent 15N recovery in the sandy loam by 37%, and increased percent utilization of 15N by bermudagrass grown in the sandy clay loam by 61–67% compared to urea applied alone. Conclusion: Applying surfactants with urea can increase bermudagrass N uptake efficiency and reduce potential N leaching.