A lysimeter study of the fate of nitrogen applied to perennial ryegrass swards: soil analyses and the final balance sheet

摘要: SUMMARY Labelled fertilizer nitrogen was applied at a rate of 40 g N m−2 to grass swards growing in lysimeters containing monoliths sandy loam soil. After 5–7 years, during which time crop uptake and drainage losses tracer were measured, the soils analysed quantify labelled remaining. Approximately one-third (range 31–35%) remained, with over 70% this residue located top 20 cm The mineralization immobilized declined exponentially; after four years release almost constant, equivalent 2% residual nitrogen. Total measured crop, soil amounted 93–98%. That unaccounted for presumed lost by denitrification, largely form dinitrogen, as rates nitrous oxide emission negligible. recovery greatest (and implication, gaseous loss smallest) when 1975 particularly warm dry summer.