Estoque de carbono e nitrogênio em solo arenoso manejado com leguminosas adubadoras

Abstract

Coconut cultivation is a source of income for many producers, especially in the Brazilian Northeast. The largest productions are in areas of sandy soils that need a greater supply of organic matter and nutrients. Green manuring with legumes is a promising practice for this purpose through proper management. The hypothesis investigated in this study was that there is a species of tree-shrub legume (Gliricídia sepium) and an ideal spacing ( 1 x 0,5m) for this legume that will result in higher levels and stocks of carbon and nitrogen in the soil. The work was carried out in Itarema (CE), in a randomized block design (CBD) experiment, with a 2 x 3 + 1 factorial scheme with four replications. In the treatments, two factors were compared: two legume species (Gliricidia sepium and Mimosa caesalpiniaefolia) and three planting spacings (1 x 1 m, 1 x 0.5 m, and 1 x 0.25 m), E1, E2, and E3, respectively. The complementary treatment showed only regeneration vegetation. Soil samples were collected to determine levels of total organic carbon (TeorC) and total nitrogen (TeorN) and stocks (EstC and EstN). The E2 spacing resulted in the highest levels of C and N in isolation (16.79 and 1.04 g kg-1, respectively). The highest EstN occurred in E2 with G. sepium (2.87 Mg ha-1). E2 provided the highest EstC (44.47 Mg ha-1). G. sepium at 1 x 0.5 m spacing is the most favorable option for C and N stocks when intercropped with coconut. However, for more conclusive results, it is recommended that the management used to be maintained for a longer.