EFEITOS DA COBERTURA DE GLIRICÍDIA (Gliricidia sepium) E ÁCIDO HÚMICO NA EFICIÊNCIA DE USO DO POTÁSSIO

Abstract

The use of vegetation cover improves the physical and chemical quality of the soil allowing greater increase in organic matter and more efficient use of nutrients by plants. The adequate supply of potassium for plants promotes increased productivity and produces effect on the absorption of other nutrients. Thus, the aim of this study was to determine the effects of vegetation cover of Gliricidia associated with applica-tion of humic acid and potassium fertilizer on the plants potassium use efficiency. The experiment was conducted in a culture system in alleys, planted with leguminous tree Gliricidia (Gliricidia sepium), located in the town experimental area camp city of Brejo-MA (3rd 38 'south latitude and 42 ° 58' west longitude). It used the hybrid corn AG 7088 cultivated between the lines of pulses, with the application of 20 t / ha of vegetation cover of Gliricidia, 78 kg / ha of potassium chloride (KCL) and 500 l / ha of humic acid. We used the 2x2x2 factorial (2 combinations of Gliricidia, 2 potassium and 2 humic acid) arranged in a randomized block design with four replications, with the following treatments: 1- Potassium (K), 2- Gliricidia (G) , 3- humic acid (HA), 4- CONTROL, 5- K + G, 6- K + AH, 7- G + AH and 8- G + AH + K. The corn plants were collected in the flowering stage and maturation is collecting three plants at each stage. The plants were separated into stem, leaves and reproductive part and then dried, crushed and subjected to digestion in nitric acid and perchloric to evaluate the nutrient content calculated the productivity of maize through the grain mass. We evaluated the content of potassium, phosphorus and nitrogen and the efficiencies were calculated potassium use by plants and nitrogen use efficiency. The results were submitted to analysis of variance and the means compared by Tukey test (p> 0.01). The corn production was higher in the treatments with plant cover Gliricidia combined with the application of potassium. The parameters of efficiency of the corn potassium use significant difference in combinations of Gliricidia + K and combina-tions of Gliricidia + K + AH, it occurred in efficiency of the use of nitrogen by corn, with decrease in treatments with the application of K. Gliricidia promoted greater effi-ciency in the use of potassium for corn.