Carbon and nitrogen stocks in cultivation systems of a Quilombola community in the Brazilian Cerrado

Quilombola communities found in the Cerrado region of Brazil are inhabited mainly by groups of African ancestry. They tend to use agricultural management without technical assistance, which degrades soil quality. The objective of this paper was to evaluate the carbon and nitrogen pools in the Quilombola areas under different soil management types. A crop sequence was evaluated in two native Cerrado areas: 1— Cerradão (NC1) and 2—Cerrado stricto sensu (NC2), as follows: planted pasture (PP1 and PP2); maize (M1 and M2); citrus-cassava intercropping (T1); and citrus monoculture (T2). The experiment was arranged in a completely randomized design with five replicates, and the plots were composed by the management systems, and the subplots were soil layers 0–10, 10–20, 20–30, 30–40, 40–50, and 50–60 cm. Conservation cultivation practices in T1 increased total organic carbon (TOC) stock (173 Mg ha −1 ), compared with M1 (120 Mg ha −1 ) and PP1 under conventional management (105 Mg ha −1 ). Down to a soil depth of 20 cm, the total N (TN) stocks were 39% and 56% lower in NC1 and PP1, respectively, than under conventional management. In area 2, the TOC stocks were similar in all treatments (mean of 118 Mg ha −1 ), and the cumulative TN stock down to the 50–60 cm layer was 10 Mg ha −1 . In the 0–20-cm layer, the N stock decreased by 15% under M2, while increases of 10% and 12% were observed in T2 and PP2, respectively. These results confirm that conservation management practices can increase carbon and nitrogen storage.