Fertilidade do solo de coqueiral após deposição de resíduos de leguminosas

Abstract

Brazilian fruit growing is responsible for generating income for rural producers. In Brazil, coconut production has been established prominently on the northeastern coast, which has high potential for the production of dried coconut. Ceará stands out in national production, being the largest producer in the northeast region. Management practices that improve soil fertility in coconut trees are desirable, with emphasis on intercropped systems and green manure. However, it is necessary to identify more suitable species and planting densities for intercropped systems with coconut trees in the climate and soil conditions of the northeastern coast. In this study, the objective was to evaluate two species of legumes at different planting densities, combined with coconut trees for green manure and improving soil fertility after the third cycle of deposition of pruning residues on the soil. The experiment was conducted in Itarema (CE), in a rainfed area, adopting a randomized block design (DBC), in a 2 x 3 + 1 factorial scheme, with four replications. The first treatment factor consisted of two species of legumes (Gliricidia sepium and Mimosa caesalpiniifolia). The second factor consisted of three planting densities of legumes (low, medium and high) and the additional treatment consisted of spontaneous vegetation (Andropogon minarum). G. sepium at high planting density resulted in higher nitrogen, potassium and calcium contents in the soil (0.81 g kg-1, 0.27 cmolc kg-1 and 1.14 cmolc kg-1, respectively). This same species led to the highest phosphorus content in the soil (1.72 mg kg-1) at the average planting density. G. sepium, at medium and high densities, resulted in the highest levels of macronutrients in the soil in relation to M. caesalpiniifolia and the control. G. sepium at medium planting density resulted in better soil fertility in coconut trees after the third cycle of pruning of aerial part biomass, when compared to M. caesalpiniifolia and the area's regeneration vegetation.