Accumulation and decomposition of litter in a grassland of Panicum maximum Jacq. and in a silvopastoral system of P. maximum and Leucaena leucocephala (Lam.) de Wit.

 


Saray Sánchez Cárdenas
Estación Experimental de Pastos y Forrajes Indio Hatuey Central España Republicana 44280, Matanzas, Cuba

 

ABSTRACT
In order to determine the accumulation and decomposition of litter and the relation of these processes to some of the biotic and abiotic factors present in a pastureland of Panicum maximum Jacq cv. Likoni and in a silvopastoral system of Panicum maximum and Leucaena leucocephala (Lam) de Wit cv. Cunningham, three trials were conducted at the Pastures and Forages Research Station “Indio Hatuey”, Matanzas. The results showed that the grassland of P. maximum accumulated 2,66 t DM ha-1 year-1, while in the sivopastoral system it was 12,49 t DM ha-1 year-1, where L. leucocephala contributed 75,6 % of the total litter. In both pasturelands the Guinea grass accumulated a lower quantity of litter during the June-December period, stage in which its higher vegetative growth occurs. In leucaena the highest litter production occurs in the period from December to January, associated to the natural falling of its leaves which occurs due to the lowest temperatures and the scarce soil humidity. In Guinea grass rainfall was the climate factor which showed higher negative correlation to litter production in both systems and in leucaena the highest negative correlation was found with the minimum temperature. In each pastureland a different litter decomposition pattern appeared. Among the species present the rate varied in the following order: leucaena higher than Guinea grass in the silvopastoral system higher than grassland of Guinea grass. The chemical composition of the litter in each pastureland influenced and varied during its decomposition process. It is possible to explain the litter decomposition process in both pasturelands from the joint action of temperature, relative humidity and rainfall. The presence of a diverse and stable fauna associated to the bags influenced the litter decomposition process. In general, the organisms that showed higher presence were Isopoda. Earthworms constituted the most numerous organisms in the pasturelands, with predominance of the species Polypheretima elongata in the silvopastoral system and Onychochaeta elegans in the monocrop of Guinea grass. The highest values of density and biomass of individuals, the predominance of Oligochaeta, as well as the best values of diversity, richness and uniformity in the silvopastoral system, indicate that the presence of leucaena in the grassland allows to enhance the biological activity of the soil and to guarantee the stability of the system.