Acúmulo de matéria seca e marcha de absorção de macronutrientes em Crotalaria spectabilis

Abstract

Among the basic premises of no-tillage, are non-soil rotation, crop rotation and biomass input to the soil, which can be done by harvesting straw (cultural residuum) or by using green manuring. In this sense a legume that has been highlighting is the Crotalaria spectabilis, for being an annual plant, of slow initial growth, that has deep pivoting root, high capacity of nutrient cycling and contribution of biomass to the soil. However in recent years there has been a lack of seeds of this genre, which demands an increase of production areas. However, nutrient demand studies for this genus are still scarce. The objective of this work was to determine the dry matter production and the accumulation of macronutrients in the aerial part of the plants at different stages of growth and development. The experiment was carried out at the Experimental Farm of Agricultural Sciences of the Universidade Federal da Grande Dourados (UFGD), municipality of Dourados, MS. The soil of the experimental area was classified as a very clayey dystrophic Red Latosol. The experimental design was randomized blocks, with twelve collection times (14, 28, 42, 56, 70, 84, 98, 112, 126, 140, 154 and 168 days, after the emergence of seedlings) and five repetitions, totaling 60 experimental units. Every collection, the plants were divided into sheet (limbus and petiole), stem + branches, vegetables and grains. The various parts of the plants were washed and dried in a forced air circulation oven at 65 ° C, until reaching constant weight and then determining the macronutrient contents. Dry matter production is slow up to 70 DAE and its maximum accumulation is 158 DAE with the highest contribution of stem + branches. During flowering period the macronutrient contents are in the following order: K > N > Ca > P > Mg > S and the export order N > K > P > Ca > S > Mg. The handling aiming the supply of nutrients to the soil should be made at 98 DAE, while for the production of biomass this should be done at 126 DAE.