Study of the decomposition of the Leucaena leucocephala foliage as green manure in the cultivation of mulberry (Morus alba)

Fidel Ruz Suárez

ABSTRACT
In order to determine the decomposition rate of the L. leucocephala foliage and the relation of this process to some of the biotic and abiotic factors present. Two trials were conducted at the Pastures and Forages Research Station “Indio Hatuey”, Matanzas. In the studied system the leucaena foliage was used as green manure in the cultivation of mulberry since ten years before. For such purpose the mulberry plantation as main crop was cut with a frequency of 90 days at a height of 30 cm. The leucaena trees were cut at a height of 2 meters, the woody biomass was collected from the system and the foliage was deposited on the soil with an application frequency of 3 months in the rainy season and 6 months in the dry season. The results showed that the foliage decomposition of leucaena as green manure showed a similar decomposition pattern in the bag types used. The moment of depositing the leucaena foliage significantly influenced its decomposition. This process is regulated to a large extent by biotic (soil fauna) and abiotic factors, especially rainfall. The taxonomic composition of the macrofauna associated to the decomposition process of leucaena foliage as green manure in the mulberry cultivation was constituted by four Phyla, six classes and seven orders, being represented by 97 % of detritivorous organisms and 3 % of predators. On the other hand, the taxonomic composition of the edaphic macrofauna communities in the system described a total of 1 540 individuals grouped in four Phyla, five classes and six orders that represent 71,87 % of epigeal and 28,12 % endogeal organisms. The values of individual density and biomass, the predominance of Oligochaeta, as well as the diversity, richness and uniformity indexes in the system, indicate that the alternative of using the leucaena forage as green manure in mulberry plantations, allows to enhance the biological activity of the soil, maintain acceptable levels of nutrients in the soil and guarantee the stability of the system. Leucaena as green manure influenced the populations of edaphic organisms, especially in the earthworms, which are considered quality indicators.