Effect of nitrogen and plant density on silage yield and quality of Maize c.v MV500 as second crop

A field experiment was conducted in order to study the effect of nitrogen fertilizer and plant density on yield and quality of Maize (Zea mays L.) cultivar, MV500 silage as second crop. This study was conducted in Agricultural Research Station of Kurdistan University during 2012 growing season. The experiment was laid out as split plot based on randomized complete block design with three replications. The main factor was three levels of nitrogen (115, 184 and 253 kg N. ha-1). Four plant densities (8, 10, 12 and 14 plants.m-2) assigned to subplots. The results showed that as nitrogen rate increased forage yield, and crude protein content increased but NDF and ADF percentage decreased. However, ash percentage did not change by nitrogen rate. Increasing in nitrogen rate more than 184Kg N/ha had no significant effect on forage yield, protein content and NDF. Although, forage yield increased and both protein content and NDF decreased as plant density increased but ADF and Ash percentage did not affect by plant density. In conclusion, nitrogen rate more than 184 Kg N/ha and plant density more than 12 pl.m-2 had no effects on forage yield and quality. Therefore, in order to avoid environmental pollutions and reduce production costs, more nitrogen rates and plant populations not recommended.