Conservative farming systems and their effects on soil organic carbon and structural quality

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Pesticides-free integrated farming systems emerge as a viable option to promote environmental protection, due to the diversification of the agroecosystem, making the soil productive and resilient. However, there is a lack of information about the influence of integration farming systems on the relationship between soil physical quality and organic matter. The objective was to determine soil organic carbon fractions, and soil structural attributes in conservative single and integrated farming systems, to verify the potential of these farming systems to increase soil organic carbon stocks and improve soil structural quality. The experiment was carried out at a pesticide-free agricultural systems. Soil samples were collected in three layers (0–0.05, 0.05–0.10, and 0.10–0.20 m) of five farming systems (Cropland - C, Livestock - L, Forestry - F, Livestock-Forestry – LF, and Crop-Livestock-Forestry - CLF) in the randomized block design. Sampling was carried out in two transects of 25 m each, collecting five samples per transect, totaling 10 samples per layer. The following soil attributes were determined: soil organic carbon (SOC), particulate organic carbon (POC), mineral-associated organic carbon (MAOC), soil organic carbon stocks (Cst), visual evaluation of soil structure (VESS), tensile strength of aggregates (TS), soil friability, weighted mean diameter (WMD), geometric mean diameter (GMD) and the aggregate stability index (ASI). At 0–0.05 m, the SOC content was up to 12% higher in the Cropland system compared to other farming systems, while at 0.05–0.10 m and 0.10–0.20 m of depth, the difference was higher, around 27% between Cropland and other farming systems. For the VESS, Cropland had the lowest score (1.35), while the higher scores were in the Forestry, and CLF systems (2.25, 2.24, respectively). Both soil organic carbon and soil physical quality were greater in all farming systems. The particulate organic carbon and weighted mean diameter were efficiently to promote changes in soil carbon inputs and structural changes. The single and integrated farming systems promoted an increase in soil organic carbon, by a rate of 3.02, 1.81, 2.17, 1.78, and 2.01 Mg ha−1 yr−1, respectively for Cropland, Livestock, Forestry, LF, and CLF. The pesticide-free farming systems, under conservative practices, were very promising in showing the increase of SOC, POC and MAOC, supporting the soil physical quality, and cooperating with the soil health.