Manejo da adubação nitrogenada sobre o comportamento produtivo do capim Mombaça

Abstract

In order to perform nitrogen fertilization in pastures, mineral resources are sought that provide cost reduction and improve biological responses in pastures. However, for the use of nitrogen sources such as urea, greater protocol planning and management of nitrogen applications are required. provide greater soil applied nitrogen use efficiency and promote flexibility in divisions of applications aimed to study and understand how nitrogen sources combined applications numbers (division of nitrogen fertilization) modify the morphogenesis structural productive, agronomic efficiency and Nitrogen nutritional status in plants of Mombasa grass, during the growing season 24-11-2018 to 12-06-2019, comprising 200 days of experimental period. We used a completely randomized design in a factorial [(3x2) +1] and evaluated three nitrogen source (ammonium sulfate, urea and urea protected) and two divisions of nitrogen applications (splitted into two or six applications), with addition of a control treatment (without application of nitrogen), with four replicates per treatment, composed of an area of 9m2 each. Morphogenic evaluations were performed to obtain morphogenic and structural variables, population density of tillers (DPP), agronomic efficiency, agronomic efficiency and nutritional status of the plant with CCM-200 Plus apparatus. The variables presented in this experiment demonstrated that the nitrogen sources maintained a greater effect on the observed responses, where it was verified that ammonium sulfate provided lower senescence rates, and also responded with a greater increase in the rate of liquid forage accumulation with superiority in 28.36% and 11.16% relative to protected urea and urea respectively. In relation to forage production, it was verified that ammonium sulphate promoted higher production and agronomic efficiency, in which 60.98 kg DM / kg of N applied. Protected urea showed greater similarity with common urea, and this effect may be due to the time of application of these sources under similar environmental conditions and therefore could respond in nitrogen utilization efficiencies equally. The smaller division of the applications showed an improvement in the nutritional status of the plant, presenting average values of 14.38 and 11.16 for two and six nitrogen applications. Based on the results presented, the ammonium sulfate still shows to be more efficient than the common and protected urea, and the nitrogen applications demonstrated greater flexibility, allowing the reduction of the nitrogen applications.