The response of Italian ryegrass to applied nitrogen in the natal midlands

Abstract

Nitrogen (N) fertilizer was applied to irrigated Italian ryegrass (Lolium multiflorum cv Midmar) pastures at varying rates over two seasons on three sites. Soils series on these sites were Metz, Griffin and Katspruit. Total N application rates ranged from zero to 1080 kg N/ha/yr. Maximum yields of 11,8,13,5 and 15,4 t/ha/yr were recorded on the Griffin, Metz and Katspruit sites respectively. Yield responses to N rate were observed up to 300–350 kg N/ha/yr. In the absence of applied N, yields ranged from 2 to 10 t/ha/yr, reflecting a large variation in the residual soil N reserves. The data are reviewed as a basis for future N recommendations.