DECOMPOSITION OF LEGUME TREE Gliricidia sepium AND Acacia angustissima IN AGROFORESTRY SYSTEMS

Os Sistemas Agroflorestais (SAFs) trazem benef\uedcios m\ufaltiplos e constituem uma alternativa para minimizar a degrada\ue7\ue3o ambiental e alcan\ue7ar um desenvolvimento sustent\ue1vel, devido \ue0 diversidade de esp\ue9cies que os comp\uf5e. O presente estudo avaliou a contribui\ue7\ue3o das leguminosas arb\uf3reas, Gliricidia sepium e Acacia angustissima , cultivadas em aleias intercaladas com banana (Musa sp.) e a\ue7a\ued ( Euterpe oleraceae ), na implanta\ue7\ue3o de Sistema Agroflorestal. Comparou-se a produ\ue7\ue3o de biomassa e ciclagem de nutrientes no SAF, com a leguminosa herb\ue1cea Pueraria phaseoloides e aduba\ue7\ue3o nitrogenada. O SAF foi implantado em maio de 2004, no Campo Experimental da Embrapa Agrobiologia, em Serop\ue9dica - RJ. O delineamento experimental foi de blocos casualizados com cinco tratamentos, constitu\ueddos das leguminosas ac\ue1cia-angust\uedssima (Acacia angustissima), kudzu-tropical ( Pueraria phaseoloides, gliric\ueddia (Gliricidia sepium) dispostas nas entrelinhas da banana e do a\ue7a\ued; al\ue9m de aduba\ue7\ue3o nitrogenada com ureia, e cobertura viva oriunda da vegeta\ue7\ue3o espont\ue2nea. Para quantificar a produ\ue7\ue3o de biomassa e libera\ue7\ue3o de N, P, Ca, Mg e K in situ foram cortadas as leguminosas e ro\ue7ado o kudzu-tropical e a vegeta\ue7\ue3o espont\ue2nea. As determina\ue7\uf5es da mat\ue9ria seca remanescente, libera\ue7\ue3o de nutrientes, constantes de decomposi\ue7\ue3o e os tempos de meia-vida dos res\uedduos vegetais foram realizadas acondicionando-se 50 g de material fresco em litterbags, dispostos na superf\uedcie do solo, tomando-se amostras aos 0, 5, 10, 15, 20, 25, 30, 40, 60 e 75 ap\uf3s o in\uedcio do experimento. Acacia angustissima e kudzu-tropical apresentaram maior produ\ue7\ue3o de biomassa seca, igual a 10,8 Mg ha-1. Os res\uedduos da gliric\ueddia resultaram em maiores constantes de decomposi\ue7\ue3o, nas duas esta\ue7\uf5es do ano.The Agroforestry Systems (SAFs) bring multiple benefits and they are an alternative to minimize environmental degradation, and to achieve a sustainable development, due to greatest diversity of species. This study evaluated the contribution of the leguminous trees, Gliric\ueddia sepium and Acacia angustissima , grown in alley cropping of banana (Musa sp.) and \u201ca\ue7a\ued\u201d palm ( Euterpe oleraceae ) used as green manure in the implantation of an Agroforestry Systems. They were compared the production of biomass, nutrients cycling, nitrogen intake, activity and diversity of soil fauna, and banana productivity in the SAF, and with the usage of the legume Pueraria phaseoloides and nitrogen fertilization. The SAF implantation occurred in May 2004, at the Research Center of Embrapa Agrobiologia, in Serop\ue9dica, Rio de Janeiro State. The following year it was planted the forest African mahogany specie ( Kaya senegalensis ), at the centre of the legumes alleys. The experimental design was of randomized blocks with five treatments and four repetitions. The treatments consisted of the leguminous trees arranged between the lines of bananas and the \u201ca\ue7a\ued\u201d palm, and they were: acacia angust\uedssima (Acacia angustissima), tropical kudzu (Pueraria phaseoloides), and gliric\ueddia (Gliric\ueddia sepium); besides application of nitrogen as urea and spontaneous vegetation. To quantify the production of biomass, and the release of N, P, Ca, Mg and K, the legumes branches were cut and the kudzu tropical and spontaneous vegetation were mowed, in the rainy and dry seasons. The determination of remaining dry matter, releasing of nutrients, decomposition rates, and half life time of plant residues were held to 50 grams of fresh material from litterbags, placed on the soil surface, sampled at 0, 5, 10, 15, 20, 25, 30, 40, 60 and 75 days after the installation of the experiment. Acacia angustissima and kudzu tropical showed higher dry biomass, 9.5 and 10.8 Mg ha-1, respectively. The gliric\ueddia residues showed the highest decomposition rates, in the two year seasons