The fate of autumn-, late winter- and spring-applied nitrogen fertilizerin a perennial ryegrass (Lolium perenne L.) seed crop on a silt loam soilin Canterbury, New Zealand

摘要

The use of fertilizer nitrogen (N) during seasons other than spring to increase seed yield of perennial ryegrass (Lolium perenne L.) has raised concerns about possible environmental contamination from fertilizer N. The fate of N-15-labelled fertilizer applied at several rates during autumn, late winder and/or spring was measured using silt loam (Eutric Cambisol (FAO)) monolith lysimeters (500mm diameter, 600 mm deep) during two, I-year lysimeter studies in Canterbury, New Zealand. Total ryegrass uptake of late winter and spring applied N-15-labelled fertilizer at harvest was greater (40 and 43%, respectively) than N fertilizer applied in autumn (18%) in 1996 and 1997, reflecting plant demand and soil immobilization in the different seasons. Consequently, in conjunction with spring N fertilizer, late winter N fertilizer application had significantly (P<0.05) greater affects on seed yields than autumn applied N fertilizer.