IMPACT OF SOIL TEXTURE ON NUTRIENT FATE

The leaching or runoff of nitrogen (N) or phosphorus (P) from sports fields is an inefficient use of nutrients and potentially harmful to the environment. A field study was conducted to determine if soil texture influences the fate and transport of N and P. Free draining lysimeters (4 m X 4 m, 430 mm deep) were filled with one of 3 soil textures (sand, sandy loam or a silt loam soil) and seeded to creeping bentgrass (Agrostis stolonifera L.). Fertilizer, containing urea-methylene urea, was applied at a rate of 150 kg N ha^-1 y^-1. Rainfall was controlled by a rainout shelter and a simulated rainfall pattern was utilized. Over the 2 y of the study, the amount of total N recovered in the clippings, as a percent of the amount applied, ranged from 8% in the sand soil, 52% in the sandy loam soil and 91% in the silt loam soil. Results were similar for P, however, the amount of leaching was ten times less than N. Conversely, more nitrate was leached past the root zone from the sand soil (9.1% of the amount applied), 1.5% from the sandy loam soil and 3.5% from the silt loam soil. Most of the remaining fertilizer N was found in the soil most likely as organic matter including roots. Phosphorus leaching was no greater in the fertilized lysimeters than the unfertilized lysimeters. The volume of leachate was 22% higher in the sand lysimeters than the other soils, that can partially explain the greater N leaching losses. Careful use of nitrogen fertilizers is necessary on sand sports fields to reduce the risk of groundwater contamination.