The Fate of Nitrogen Fertilizer Applied to Turfgrass¹

Field plots, instrumented with suction lysimeter and neutron probe access pipes, were used to study the fate of nitrogenous fertilizer applied to turfgrass grown on a sandy loam soil. Fertilizer N was applied to each plot at a rate of 195 kg ha −1 in each of the first 2 years and 180 kg ha −1 in the 3rd year to each plot. The fertilizer N was in a 50:50 split application in May and September of each year. Grass clippings were returned, after subsampling, to two of the four plots. In the 3rd year, the use of 15 N as a tracer in conjunction with grass clipping management provided the means to quantify the N in the grass derived from fertilizer, soil, the current year's grass clippings, and the previous 2 years of grass clippings. For example, where clippings were not returned, about equal quantities of N were derived from soil and fertilizer. Where clippings were returned, the yield of grass increased by about one‐third and nearly equal proportions of N in the plant tissue came from soil, fertilizer, and grass clippings.