Dynamics of plant organic matter decomposition in different agricultural landscapes

Dinâmica da decomposição da matéria orgânica vegetal em diferentes paisagens agrícolas

ABSTRACT

The functioning of ecosystems or agroecosystems is mainly dependent on the soil-litterfall interaction. Thus, the objective of this work was to evaluate the effect of different soil use and management systems on the dynamics of decomposition of plant residues of Azadirachta indica (neem) and Gliricidia sepium (gliricidia). The study was conducted in four land occupation systems, namely: remaining forest, agroforestry, agricultural mandala, and pasture. The decomposition rate was estimated using nylon bags (litter bags), containing 20 g of leaves of A. indica and G. sepium, which were arranged on the soil surface of each area for 18, 36, 54, 72, 90, and 108 days. A completely randomized design was used for each species, considering each area as one treatment, with four replications for each collection. The data were subjected to regression analysis and the means were compared by the Tukey's test (p<0.05). More than 85% and 90% of A. indica and G. sepium plant matters, respectively, had been decomposed after 108 days, regardless of the system evaluated, denoting that these species present high decomposition rates. The phytomass half-life time varied from 16 to 23 days for G. sepium and from 25 to 37 days for A. indica, depending on the land use system. Edaphic temperature, soil water content, and leaf physical and chemical characteristics are weight loss predictors. The results provide important information to enable forest management practices.

Keywords:
Agroecosystems; Azadirachta indica ; Phytomass leaf; Gliricidia sepium