Soybean expansion impacts on soil organic matter in the eastern region of the Maranhão State (Northeastern Brazil)

Recently, the eastern region of the Maranhão state (Northeastern Brazil) became a hotspot of land‐use change (LUC) directly from native vegetation to soybean cultivation, but due to the soil characteristics, LUC has caused substantial soil organic carbon (SOC) and nitrogen depletion. Therefore, we q...

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Bibliographic Details
Published in:Soil use and management 2022-04, Vol.38 (2), p.1203-1216
Main Authors: Siqueira‐Neto, Marcos, Popin, Gustavo V., Ferrão, Gregori E., Santos, Arthur K. B., Cerri, Carlos E. P., Ferreira, Tiago O.
Format: Article
Language:English
Subjects:
Acrisol
Agricultural management
Carbon
Depletion
Economics
Emissions
Greenhouse gases
labile carbon
Land use
microbial carbon
Microorganisms
Organic carbon
Organic matter
Organic soils
Plows
Profitability
Soil
Soil characteristics
Soil management
soil organic carbon
Soil organic matter
soil organic matter fractionation
Soils
Soybeans
Stocks
Sustainability
Tillage
Vegetation
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Summary:Recently, the eastern region of the Maranhão state (Northeastern Brazil) became a hotspot of land‐use change (LUC) directly from native vegetation to soybean cultivation, but due to the soil characteristics, LUC has caused substantial soil organic carbon (SOC) and nitrogen depletion. Therefore, we quantified these impacts arising from two factors: (i) different timeframes after LUC and (ii) contrasting soil management practices. For the first study, soil samples (0–30 cm; six replicates) were taken on soybean fields year one, year eight and 15 years after LUC. It the second study, another area was sampled, of which part was managed under no‐tillage (NT) and the other using a mouldboard plough (MP). For both studies, native vegetation (NV) was sampled as the control. NV stored about 50 Mg of carbon (C) ha−1; but LUC reduced C stocks by 35% (after 8 and 15 years); moreover, labile‐C decreased between 20% and 45%, while, microbial‐C decreased between 20% and 60%, considering the interval between year one and 15 years. Regarding soil management, the MP did not cause differences on C stock (24 Mg C ha−1) in comparison to NT; however, both labile‐C and microbial‐C decreased by 15% to NT, while, decreased by 40% to MP. These results lead us to believe that, since LUC is inevitable, we suggested the adoption of the best agricultural management practices, in order to preserve/increase the SOC, reducing the impacts on GHG emissions and, thus, achieving sustainability and profitability.
ISSN:0266-0032
1475-2743
DOI:10.1111/sum.12785