Comparação de ciclagem de nutrientes em pastagens convencionais, sistemas silvipastoris e floresta estacional semidecídua

Abstract

Silvopastoral systems combine trees, pastures and livestock. Cattle production systems cause fewer ecosystem effects compared to conventional pasture systems. The cycle of organic capacity has an essential role, once that integrated the biogeochemical cycles, which are the following cycle of elements and energy between the environment and the organisms. The litter is of fundamental importance for the transfer of nutrients to the system, with much of the nutrients absorbed by the vegetation to the soil through its deposition. The decomposition of litter is one of the main ways of filling organic and inorganic fields for the processes of nutrient control and control of return to the system. The objective of this work was to compare and analyze the decomposition of litter and its nutrients in production systems with the monoculture of grasses and grasses + trees, using a semideciduous seasonal forest as a control. For litter collection, three replicates of samples collected monthly for 12 months, through collectors 0.5 m x 0.5 m. In the case of the Urochloa litter, non-fallen senescent material was collected alone, in 0.5 m x 0.5 m frames. The dry matter, organic matter, carbon, lignin, cellulose, macro and micronutrients elements were analyzed both in the dry season and in all systems. For the decomposition study, senescent leaves with no sign of decomposition were collected in each of the systems. Then, 10 g of dried leaves were packed in nylon bags, measuring 25 cm x 25 cm, 2 mm thick, steel at 60 ° C for 72 hours and finally weighed. Later, these pockets were made on a litter accumulated in the soil. The degradation rate, done in six periods, in dry season: 0, 4, 8, 16, 32, 64 and 128 days, with three replicates each, being withdrawn and weighed at the end of each year and taken to nutrient analysis. There was no significant difference in litter between the production systems, however, the greater existential support in pastures with native trees, demonstrating that the larger systems of greater availability of nutrients to the soil. It was not different between the systems in relation to the decomposition process, being greater only in the forest. The production of nutrition, we conclude that pastoral systems with native species the soil tends to be richer, reducing the impact of livestock.