Soil Organic Matter Changes in Agroforestry and Organic Farming in the Semi-Arid Region of Northeastern Brazil

摘要

The development of management strategies aiming to increase soil quality in Brazilian semi-arid regions, including the improvement of soil organic matter (SOM) status, is still scarce. In general, most of the traditional farming practices adopted in agricultural fields in Northeast Brazil (semi-arid) contribute to reduce SOM levels. Thus, alternative management practices must be implemented to improve soil quality in different agricultural production systems. Within this context, agroforestry and organic farming have been considered suitable management options to cope with the semi-arid climate despite of its environmental constraints. This study aimed at presenting results from well established experiments on agroforestry and organic farming performed in Sobral, Guaraciaba do Norte and Ubajara counties, all located in the State of Ceara, Brazil. In agroforestry, agrosilvopastoral and silvopastoral designs may be considered as important options to increase soil organic C stocks, with consequences in the different SOM pools, including labile C. Organic farming has been implemented in both small and large scale agriculture, and it also represents a good strategy to increase the status of SOM, even in sandy soils as observed at Ubajara county. Obviously, agronomic, economic and social aspects should be linked to the environmental benefits brought about through the adoption of agroforestry and/or organic cultivation. Notwithstanding, the discussion involving the improvement of food production in Brazilian semi-arid must regard both types of agroecosystems as suitable options to increase the status of SOM, which represents the starting point for recovering soil quality, and consequently, enhancing productivity.