ATRIBUTOS QUÍMICOS DO SOLO E ESTADO NUTRICIONAL DE COQUEIROANÃO FERTIGADO COM NITROGÊNIO E POTÁSSIO

Abstract

The objective of this work was to study the effects of N and K2O doses applied through fertigation in soil fertility and nutritional status. The experiment was carried out during April, 2002 until March 2004, on Experimental Farm of the Empresa de Pesquisa Agropecuária of the State of Rio Grande do Norte (EMPARN), Brazil. The statistical design was in a completely randomized block with 4 replication, using for composition of treatments Plan Puebla III experimental matrix, treatments being composed of combination of two factors: nitrogen and potassium doses in the form of urea and potassium chloride, respectively. In all 10 treatments, defining the interval for N (256 to 4874 g plant-1 year-1) and K2O (258 to 4872 g plant-1 year-1) were applied through fertigation with microsprinkler irrigation system. The contents of nutrients in the soil presented great variation and tended to decrease with time. The doses of N decreased the pH and contents of Ca and Mg although increased the availability of P in soil and favored its absorption by plant. A negative gradient in concentration of nutrients under fertigation was observed from the soil surface. The K content in leaf 14 were increased with increase in doses of K2O via fertigation presenting high correlation with number of fruits. The application of K in soil increased the contents of Cl and Mg in leaf 14 and decreased the contents of Na, while the application of N in soil increased the contents of Mn in leaves.