Aspectos agronômicos e zootécnicos do sorgo forrageiro cultivado sob diferentes lâminas de irrigação com água salina e adubação nitrogenada

Abstract

The Brazilian semi-arid region is characterized by long periods of drought, lack of water and climatic conditions that cause in the accumulation of salts, compromising the agricultural and agricultural exploitation. There are techniques of coexistence with these situations that are satisfactory, among them, we have the nitrogen fertilization and the use of forage crops tolerant to these conditions, as forage sorghum. The objective of this study was to evaluate the effects of different irrigation slides with saline water and nitrogen fertilization under the agronomic aspects of growth and productivity and chemical and bromatological aspects of forage sorghum in consecutive cycles. The experiment was carried out at the Serra Talhada Academic Unit (UAST) under field conditions, installed in randomized blocks, evaluating forage sorghum IPA 467- 4 -2 in a consecutive cycle, submitted to 4 irrigation slides (28, 36, 44 and 52%) and 4 levels of nitrogen fertilization (0, 100, 200, 300 kg ha-1), using urea as a source of N. Biometric and productivity evaluations were performed on forage sorghum as well as bromatological analyzes. Data were submitted to analysis of variance, test of means, simple linear correlation and were adjusted to the regression model. The higher nitrogen dose together with the higher irrigation depth provided higher crop growth, lower senescent leaves and higher yield of green matter in both cycles. Harvest period, slides and doses influenced NDF and FDA levels, as well as CP and DM levels. Nitrogen fertilization inhibited the toxicity and absorption of chloride and sodium ions in the same condition, even the two existing in the same proportion in the plant. Sodium and chloride contents showed a positive correlation. The linear simple correlation between the attributes of the plant, leaf, dose and productivity was, although low in the majority, positive, being negative only for the number of dead leaves. The supply of N favored the absorption of K +, inhibiting Na + and reducing the absorption of Cl-.