IMPACT OF DIFFERENT USE SYSTEMS ON TOTAL AND MINERALIZABLE ORGANIC CARBON IN A SANDY SOIL

Abstract

This study aimed to evaluate the impact of different land use systems on total organic carbon (TOC) contents and stocks and the daily and total evolution of mineralizable carbon (C-CO2) in a sandy-textured Argissolo Vermelho Amarelo. The study was carried out in Eldorado, MS, in a reference area of Native Forest (NF) and three managed areas: Permanent Pasture (PP), Direct Sowing b(DS), and an area of Private Natural Heritage Reserve (PNHR) in the process of natural regeneration. Soil samples from the 0.0-0.05, 0.05-0.10, and 0.10-0.20 m layers were collected to assess soil density (Sd), TOC contents, with subsequent calculations of the stratification index (SI), carbon stock (StockC), and variation of the total organic carbon stock (∆StockC), in addition to the determination of daily emission and calculation of total C-CO2 accumulation. The NF area had the highest levels and stocks of TOC, reaching 16.42 g kg-1 and 20.90 Mg ha-1, respectively. On the other hand, the PP and PNHR areas had the lowest content and StockC. The areas of PP, DS, PNHR, and NF presented SI values of 1.08, 1.13, 1.32, and 1.61, respectively. The NF area showed higher peaks and a higher total accumulation of C-CO2, inferring the highest biological activity in this area. By multivariate analysis, none of the managed areas was close to the NF in quality. The worst results considering the evaluated attributes were observed in the areas of PP and PNHR due to the stage of degradation of these areas as a result of exploration and land use history.