Soil organic fractions in areas under agroecological management in Capivari, Duque de Caxias, RJ

Abstract

This study aimed to evaluate soil organic matter (SOM) fractions in areas under different vegetable coverings and recent crop systems under agroecological management in low lands in the district of Capivari, Duque de Caxias, RJ. Three crop areas were selected: passion fruit, subdivided in passion fruit located in upland (PFUL) and lowland (PFLL) of the landscape; both in consortium, and crotalaria in rotation. An adjacent area of scrub was included to represent the original condition. Total organic carbon (TOC) and respective stock (StTOC) was quantified. Particulate organic carbon (POC)
and organic carbon associated to minerals (CAM) were separated by particle size fractionating method (sieving). Carbon stocks of each fraction (StPOC  and StCAM) and carbon management index (CMI) were determined. The highest values of TOC, StTOC, POC and StPOC were observed in the PFUL covering. POC allowed the identification of changes caused by the management in the three evaluated areas, being more efficient than TOC in recently implanted experiments. CMI was efficient to discriminate changes among crop systems, however, new evaluation will be necessary with time, due to the small time of cultivation of the areas.