Soil carbon storage in three tropical bovine cattle systems under exploitation

Abstract

In areas of the Institute of Animal Science during the years 2004, 2005 and 2006 was determined the soil carbon storage in three tropical cattle raising systems under exploitation with bovine cattle: a) silvopastoral based on Panicum maximum and Leucaena leucocephala; b) monoculture of Panicum maximum and c) grass association with a mixture of creeping legumes. In each one of the systems soil carbon storage (SCS), organic matter and apparent density were determined. Botanical composition, frequency of species appearance and soil cover were evaluated in each system. In all systems, the highest carbon deposit occurred from 0 to 15 cm depth. The silvopastoral system and that of the legume mixture increased the SCS with the time of exploitation, which varied from 54.4 to 65.3 t ha-1 and from 50.6 to 60.4 t ha-1, respectively. The system with guinea grass monoculture decreased the SCS with the time of exploitation, which was of 60.4 to 43.7 t ha-1. It is concluded that SCS contents are in function of the use and management of the soil and directly related to the organic matter content. In the depth from 0 to 45, the greatest accumulation of CSC occurred in the first 15 cm. The silvopastoral system and that of the creeping legume mixture had a gradual increase in the SCS with the exploitation time, which turns them into viable alternatives for carbon capture in grassland agricultural ecosystems. The monoculture system showed decline signs, with which were related their lower values in the SCS. It is recommended to use silvopastoral systems and of creeping legume mixtures to improve the soil C storage and to attain systems of stable and productive improved grasses.
Key words: silvograzing, monoculture, creeping legumes