Larissa de Souza Bortoloa, Victória Santos Souzaa, Rodrigo Estevam Munhoz de Almeidab, Dener Márcio da Silva Oliveirac, Lucas Pecci Canisaresa, Lucas Freitas Nogueira Souzaa, Maurício Roberto Cherubina d
- aDepartment of Soil Science, “Luiz de Queiroz” College of Agriculture – University of São Paulo (ESALQ/USP), Piracicaba, SP, Brazil
- bEmbrapa Pesca e Aquicultura, Palmas, Tocantins, Brazil
- cInstitute of Agricultural Sciences, Federal University of Viçosa, Florestal, MG, Brazil
- dCenter for Carbon Research in Tropical Agriculture (CCARBON) – University of São Paulo, Piracicaba, SP, Brazil
Highlights
- Long-term experiment (10 years) demonstrates the benefits of overseeding soybeans cover crops;
- High-biomass forage species increase soil carbon stocks and improve soybean yields;
- Continuous pearl millet cultivation leads to carbon loss without yield improvement;
- Isotopic analysis reveals soybean residues as a key contributor to soil organic matter formation.
Abstract
Integrating perennial tropical forages into soybean systems is an alternative to enhance soil organic carbon (SOC) stocks and crop productivity under challenging tropical conditions in Brazil’s MATOPIBA region. This 10-year study evaluated the effects of overseeding perennial forages (Urochloa and Megathyrsus genera) and annual (Pennisetum glaucum) on SOC stocks and soybean yield, compared to fallow and pasture systems. For characterization of soil carbon and nitrogen stocks, soil samples were collected in the 0–30 cm and 0–100 cm deep and stable isotopes were used to trace carbon inputs. Perennial forages increased SOC stocks from up to 0.9 Mg ha−1 yr−1.,M. maximus reached the highest gains (94 Mg ha−1on meter deep), whereas, Pearl millet system showed carbon losses of 0.25 Mg ha−1 yr−1.The average yield of soybean under perennial forages was 4142 kg ha−1, which represents a percentage of 13 and 20 % higher than pearl millet and fallow, respectively. Isotopic analysis indicated soybean residues as the primary contributor to SOC gains, likely due to their high nitrogen content enhancing microbial efficiency. Overseeding perennial forages improved soil carbon and soybean productivity, offering a sustainable intensification strategy for MATOPIBA regions with sandy soils and short rainy seasons. In contrast, pearl millet produced a limited amount of biomass and failed to sustain SOC or yield benefits. These facts emphasize the hypothesis of the benefits that perennial forages promote climate-smart solutions by increasing C sequestration, crop productivity, and agricultural resilience in tropical agroecosystems.
Keywords
Soil carbon sequestration; Sustainable intensification; Tropical forages; Soybean yield; MATOPIBA; Perennial grasses
