Produção do capim megathyrsus maximus cv. mombaça sob diferentes fontes e doses de adubação nitrogenada

Abstract

Considering the importance of minimizing nitrogen losses and increasing forage production, this work was carried out with the aim of evaluating the effect of applying two nitrogen sources applied in increasing doses on the production of Megathyrsus maximus cv. mombassa. The forage grass Megathyrsus maximus cv. mombassa under two sources of nitrogen, urea and YaraBela (ammonium nitrate), and five doses of nitrogen 0; 25; 50 and 75 kg of N/ha/cycle, in a randomized block design. To standardize the area, an initial forage cut was made at a height of 10 cm from the soil and then every 28 days, totaling four cuts and three evaluation cycles. Nitrogen fertilization was performed at each cut. In a forage subsample, the separation of the leaf blade and stem components at the height of the ligula, dead material and weeds was carried out. The variables height, leaf dry mass, stem dry mass, total forage dry mass production, leaf/stem ratio and weeds (%) were not influenced by the tested nitrogen sources (P> 0.05). The production of forage dry mass and the production of leaf dry matter were adapted to the quadratic regression model, the production increased with the increase of N doses, however, the increasing effect on production was reduced with the increase applied doses. The forage height canopy responded linearly (P <0.05), for each kg of N applied there was an increase in height of 0.37 cm. For each kg of N applied, the stem DM increased 6.18 kg/ha. The percentage of invasive plants decreased linearly with the increase of nitrogen doses. Nitrogen fertilization increases the productivity of mombassa grass and allows the reduction of pasture infestation by invasive plants. In regions where there is an adequate distribution of rainfall over the rainy season, there is no difference between the sources of nitrogen (urea and ammonium nitrate - YaraBela®).