Carbon and nitrogen stocks and organic matter fractions in the topsoil of traditional and agrisilvicultural systems in the Southeast of Brazil

Abstract

The adoption of conservationist systems can improve the protection of soil organic matter (SOM) and mitigate greenhouse gas emissions. Thus, we aimed to quantify the soil carbon (C) and nitrogen (N) stocks, C content in the SOM fractions and microbial C (Cmic) in the topsoil of an Acrisol under traditional and agrisilvicultural systems in the Southeast of Brazil. The evaluated treatments were native vegetation of Cerrado (NV), pasture of Urochloa brizantha (PAST), monoculture of pigeon pea (MCP), and agrisilvicultural system (Eucalyptus+pigeon pea; AGS). Soil samples were collected at depths of 0–5, 5–10, and 10–20cm to determine the soil C and N contents and stocks, C associated with granulometric and humic fractions of SOM, and soil Cmic. The C contents in AGS and MCP systems were similar to NV at 5–10 and 10–20cm, and soil C stocks in AGS were similar to NV and higher than in PAST system at 0–20cm. We found a higher percentage of protected C in the silt+clay fraction, and the AGS system contributed to an increase in this organomineral fraction at 10–20cm soil depth. The C contents in the free light fraction (0–5cm) and humin (5–10 and 10–20cm) were also similar between AGS and NV, giving greater protection of SOM in both systems. For Cmic and microbial quotient values we found no differences among the evaluated systems. The results indicated that after conversion of NV to different land uses, the AGS system more effectively increased the C stocks in the topsoil and protected the SOM.

Evaluation of Buffel Grass Forage Production, Soil Microbial Biomass, and Enzymatic Activity in Silvopastoral Systems

“…According to Ferreira et al (2017), microbiological attributes and soil quality indicators are affected by the composition of the production system, the characteristics of plant residues, and anthropic interventions. Our results at 5–10 cm and 10–20 cm in the silvopastoral systems were similar or higher to those found by Frazão et al (2021) in the same soil type under native vegetation, indicating that integrated production systems contribute to an increase in soil microbial biomass.…”

Management of marandu grass pasture increases soil carbon and nitrogen stocks in forest grazing systems in the brazilian cerrado

“…The results presented in Table 1 indicate that marandu grass forage plants maintained at 50 cm height and shaded with eucalyptus in the integrated system increase the contents of OC, N and SOM, compared to marandu grass monoculture. Increases in OC and N stocks in topsoil layers have been evidenced in studies introducing SSP in the Brazilian Cerrado (Almeida et al, 2021;Frazão et al, 2021), but without evaluating the in uence of pasture management.…”

“…Studies have shown that the integration of production with pastures, with the adoption of forest grazing systems, can increase soil OC stocks and improve land use sustainability (Almeida et al, 2021;Frazão et al, 2021;Jose and Dollinger, 2019;Ribeiro et al, 2019;Schinato et al, 2023), increase the quality and productivity of agricultural products, and the conservation of environmental resources (Hanisch et al, 2022;Santos et al, 2019).…”

Changing the land use from degraded pasture into integrated farming systems enhance soil carbon stocks in the Cerrado biome

“…After the plantation of trees, forage species and grain crops were combined in a consortium and/or succession. The management practices and cultures included in this integrated farming system have been described in detail by Rodrigues, Santos, Sampaio, and Fernandes (2017) and Frazão et al (2021).…”

“…Land-use types that increase the organic carbon content and reduce the GHG emissions must be adopted to control the negative impacts of climate change (Toru & Kibret, 2019). The conversion of low-productivity pastures into integrated farming systems can facilitate the soil carbon accumulation (Frazão et al, 2021).…”