Influence of fertilizer nitrogen on herbage dry matter and nitrogen yields and botanical composition of a grazed grass clover pasture
Ball, R.; Molloy, L.F.; Ross, D.J.
New Zealand Journal of Agricultural Research 21(1): 47-56
ISSN/ISBN: 0028-8233 Accession: 005684755
The response of a ryegrass[Lolium (multiflorum .times. perenne) .times. perenne]-white clover [Trifolium repens] pasture, grazed by sheep, to lime NH4NO3 was studied. A dry matter (DM) yield response to annual inputs of 112 and 448 kg N/ha was clearly established. The heavier rate gave diminishing returns, but resulted in a 20% increase in total yield over the 18 t [tons] DM/ha recorded in the absence of applied N. Ryegrass responded and clover was suppressed with N use. The reduction in clover yield was small (15%) and unrelated to N rate. Herbage N yields are reported. Annual turnover of N through herbage ranged 720 kg/ha for the control (no N) to 920 kg/ha with the heavier N input. Apparent recoveries of N for the year, 38 and 46%, respectively, and are considered in relation to N rate, seasonal influences and effects of N on clover performance.