Influência da adubação nitrogenada na produtividade de silagem e grãos de milho

Abstract

Corn silage (Zea mays) is one of the mostly used practices to store food for dairy-cattle feeding during the forage shortage period. There are still questions to maximize the gains in quality and quantity of corn silage, especially regarding the choice of cultivars, the crop treatment and silage process. In this sense, a field experiment was conducted in order to verify the influence of nitrogen fertilization on yield characteristics of corn silage. The experiment was conducted with the corn hybrid Maximus®, which was submitted to different doses and times of nitrogen application (N) in broadcast fertilization. The experimental design used was of randomized blocks with four replicates. In the plots, we allocated the N rates of 0 kg (control), 120 and 180 kg.ha-1; we also allocated the application times, divided into: one application (V6 stage), two applications (V4 and V8 stage), and three applications (planting (banded fertilization), V5 and V10 stages). In the corn silage harvest, some variables were quantified, as: stem diameter, ear insertion height, percentage of green leaves, production of natural matter and dry matter production. At the end of the crop cycle we quantified the grain productivity of the crop, the weight of one thousand grains, the size of the ear and the number of grains per ear. It was observed that the broadcast application of nitrogen positively influenced the performance of the crop regarding the quality of the plant and mass productivity. Different times of N application result in a lower effect of the parameters that determine the final quality of the silage, being these parameters more influenced by the quantity of the N dose applied. The dry matter, in the best treatment, showed a 46.7% higher productivity when compared to the control. The mean values of grain yield were of 8301.7 ha1. The productivity of the crop was more influenced by the applied doses of N, with no significant variation according to the time of application. The split of the application of N doses in three different stages of the crop did not promote a raise in the productive characteristics of the crop, in special, by the delay in the last application.