YIELD OF FORAGE MAIZE IN RESPONSE TO NITROGEN FERTILIZATION AND PLANT DENSITY

Abstract

In this study we determined the effect of plant density and nitrogen rates on forage maize yield and nitrogen use efficiency during the Summer season at the Comarca Lagunera, México, through two field experiments, one in 1998 and the other in 1999. Treatments consisted of three nitrogen rates (125, 250 and 375 kg ha^-1) and five plant densities (9, 12, 15, 18 and 21 plants/m² in 1998; and 8.5, 11.0, 13.5, 16.0, and 18.5 plants/m² in 1999). Dry matter (DM) yield, N concentration, N uptake and N use efficiency were determined. Plant densities higher than 9.0 plants/m² did not significantly increase DM yield. Nitrogen use efficiency was highest at 125 kg N ha^-1, due to a better use of soil available N; the application of 125 kg N ha^-1 plus the available N at planting was enough for a N uptake between 139 and 201.8 kg N ha^-1, and for obtaining a similar yield than with 250 kg N ha^-1. Nitrogen rate of 375 kg N ha^-1 increased DM yield between 11.8 and 17.5 %, but decreased N use efficiency.