Can short-term pasture management increase C balance in the Atlantic Rainforest?

Few studies have shown the importance of different pasture management practices on C storage and the reduction of CO2-C emissions in tropical conditions. The objective of the present study was to determine short-term changes in C pools and C balance from different pasture management practices established in the Atlantic Rainforest. A field study was carried out in Alegre, ES, Brazil from September 2013 to August 2014 to investigate the first-year effect of pasture management practices on a Udult clayey soil. The different pasture management practices studied included the following: control (CON), chiseled (CHI), fertilized (FER), burned (BUR), integrated with crop-livestock (iCL) systems, and plowed and harrowed (PH). Monthly disturbed and undisturbed soil samples were taken at two different layers (0.00-0.05 and 0.05-0.20 m) for chemical, physical, and organic matter characterization. C inputs monitored in aboveground pools included plant aerial parts and litter, and belowground pools included roots and soil C stocks. C outputs monitored were CO2-C emissions, erosion water, and sediment. C balance was considered the difference between inputs and outputs in each treatment during four seasons. The spring and summer seasons had a strong influence on C inputs and outputs where there is significant difference between spring and summer, while the autumn and winter seasons had less influence. All pasture management practices exhibited positive C balance after 1 year. High values of C balance were verified in pastures fertilized (FER) (53.04 Mg ha-1 year-1. Intermediate C balance was found in the burned (BUR) (40.84 Mg ha-1 year-1), traditional control (CON) (40.31 Mg ha-1 year-1), and in the plowing and harrowing (PH) (40.02 Mg ha-1 year-1) management practices. The practices of chiseled (40.00 Mg ha-1 year-1) and integrated crop-livestock systems (iCL) (59.06 Mg ha-1 year-1) resulted in low C balance.