AVALIAÇÃO DE ESPÉCIES DE COBERTURAS DO SOLO COM POTENCIAL DE USO EM SISTEMA DE PLANTIO DIRETO

A condition for the application of the no-tillage system in the cerrado is the production of biomass to allow a good covering of the soil. An experiment was carried out in the field, in Oxysoil (Latossolo Vermelho Amarelo), at Goiânia, Goias, Brazil, to assess biomass yield from eight soil covering species and two crop systems (ten experimental treatments): pig bean ( Canavalia ensiforme ), mucunas ( Stizolobium dierrigianum and Stizolobium muriens ), millet ( Pennisetum typhoides ), crotalaria ( Crotalaria juncea ), buckwheat ( Fagopyrum esculentum ), black oats ( Avena strigosa ) and brachiaria grass ( Brachiaria ruziziensis ), and the minimum tillage and no-tillage with the weeds as ground cover. The biomass yield was evaluated 20, 50, 80 and 90 days after the emergence of the plants. After 180 and 300 days, dry biomass of crop residues was weigh. After 80 days, C, N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn levels were analyzed. The largest yields of total and residual biomass were obtained with Brachiaria and Crotalaria juncea , which extracted of nutrients from the soil better. Buckwheat was found to be the most efficient species to extract N, K, Ca and micronutrients, and millet and brachiaria removed the highest amounts of P from the soil studied. KEY-WORDS: Biomass; leguminous; green fertilizer.