DECOMPOSIÇÃO SUPERFICIAL E SUBSUPERFICIAL DE FOLHAS DE FAVA (Phaseolus lunatus L.) NA REGIÃO DO BREJO DA PARAIBA, BRASIL

The lack of adequate management practices favors the reduction of the soil organic matter and fertility. The broad bean (Phaseolus lunatus) is a leguminous plant appropriate to human and animal feeding that is also cultivated to biomass production and soil incorporation as green manure. The objective of this work was to evaluate the rate of decomposition of broad bean leaves. Broad bean leaves (10 g) in nylon bags were set on the surface or 15 cm deep in the soil and leaf decomposition were evaluated every 15 days from October to December 2002, with the 2 x 5 factorial treatments, replicated three times and randomly assigned to the plots according to a completely random design. Buried leaves showed higher decomposition rate (96.7%) at day 75, while decomposition rate was higher (65.2%) at day 60 when the leaves were on the surface of the soil. Thus, as a result it is concluded that broad bean plants can be recommended for green manuring, being decomposed faster when incorporate to the soil.