ChileanJAR

The effect of three nitrogen fertilization rates and four planting densities on dry matter and protein yield of silage corn (Zea mays L.) was evaluated. The densities were as follows: 70,000, 90,000, 110,000 and 130,000 plants ha^-1, and the nitrogen rates: 150, 300 and 450 kg N ha^-1, giving a total of 12 treatments which were evaluated in 22.4 m² plots. Both factors were evaluated in a completely randomized block design with 4 replicates in a 2 x 4 factorial arrangement. Evaluation was performed between October and March 1996-1997. Data were analyzed in an analysis of variance and means were compared using the Duncan test and regression analysis. As nitrogen applied to corn increased, forage yield and protein yield per ha also increased. This increase was 3.8 DM ha^-1 when nitrogen was increased from 150 to 300 kg N ha^-1, and 2.0 t DM ha^-1 as N increased from 300 to 450 kg N ha^-1. Higher plant density produces increased forage production per hectare, but protein yield was not affected. Higher levels of N fertilization increased protein percentage in forage. Higher levels of N application reduced efficiency of N use (74%) as compared to 94% when N application was 150 kg N ha^-1; N losses presented the opposite tendency. Higher levels of N application reduced the percentage of dry leaves in the plants, varying between 44 and 28% for fertilization of 150 and 450 kg N ha^-1, respectively.