Reference
Tarre, R., Macedo, R., Cantarutti, R.B., Rezende, C.de P., Pereira, J.M., Ferreira, E., Alves, B.J.R., Urquiaga, S. and Boddey, R.M. 2001. The effect of the presence of a forage legume on nitrogen and carbon levels in soils under Brachiaria pastures in the Atlantic forest region of the South of Bahia, Brazil. Plant and Soil 234: 15-26.
What was done
Soil carbon contents were measured in Brachiaria (C4 grass) pastures that had replaced native forests in the Atlantic region south of Bahia, Brazil. The pastures contained either Brachiaria alone or mixtures of Brachiaria and Desmodium ovalifolium, a nitrogen-fixing legume. Measurements were made over a nine-year period and included data from adjacent forested areas for comparative purposes.
What was learned
The clearing of native forests resulted in initial decreases in soil carbon contents. After the establishment of productive Brachiaria pastures, however, soil carbon stocks began to increase, eventually surpassing those measured in adjacent forest soils. Moreover, the total soil carbon contents present in the first 100 cm of soil were greater in mixed-species pastures than they were in Brachiaria monocultures.
What it means
If land-use changes in the Atlantic region south of Bahia, Brazil continue to result in the replacement of native forests with Brachiaria pastures, the total carbon stocks of their associated soils may ultimately increase to values greater than those of adjacent native forest soils, as long as the pastures are productively managed, perhaps by including nitrogen-fixing legumes that typically are highly responsive to atmospheric CO2 enrichment.
Reviewed 30 October 2002