Nitrification, Denitrification, and Sorption-Desorption of NH4-N in Sands during Water Movement to Subsurface Drains

摘要

Isotopically labelled (15N-depleted (NH4)2SO4) N fertilizer was applied at a rate of 115 kg N/ha to a Florida citrus grove located in a subsurface drained Spodosol in order to determine the fate of applied N. The fertilizer was applied to one 0.22-ha field plot each of shallow-tilled (ST), deep-tilled (DT), and deep-limed/tilled (DTL) soil. Analyses of soil, soil solution, drainage water, and citrus leaf samples revealed that much of the NH4-N was nitrified to form NO3-N during the first 42 days after application of fertilizer. Partially because of a local drought, most of the applied N was absorbed by plant roots during the first 134 days and leaching losses in drainage water were less than 4% of the amount applied.