Shallow soils in dryland ecosystems: Drivers of C accumulation and land management implications

Autor(es)

Pinheiro Junior, C. Roberto ; Ferreira, Tiago Osorio ; Oliveira Filho, Jose de Souza ; Queiroz, Hermano Melo ; Canisares, Lucas Pecci ; Greschuk, Lucas T. ; Cerri, Carlos Eduardo Pellegrino ; Pereira, Marcos Gervasio ; Pereira, Goncalo Amarante Guimaraes ; Cherubin, Mauricio Roberto

• Tipo de documento: Artigo Científico
• Fonte: GEODERMA REGIONAL; v. 38, p. 9-pg., 2024-08-14.

Resumo

Shallow soils (i.e., Lithic Entisols) cover about 20% of Brazilian drylands. Inherent soil characteristics (i.e., shallow depths) and water scarcity restrict plant growth and carbon (C) inputs in these soils. In such a sensitive ecosystem, sustainable land management options are key to promoting socio-economic development and ensuring food security. Here, we use a dataset of 50 Lithic Entisol profiles distributed within the Brazilian drylands (northeastern region) to: (i) investigate the effects of land-use (cropland, grassland, and native forest), climate (semi-arid and dry sub-humid), and slope classes (0-3%, 3-8%, 8-20% and 20-45%) on soil C accumulation; and (ii) evaluate how understanding multiple drivers C accumulation can support the identification of sustainable land management options. The results suggested that land use does not affect C stock and C/N ratio, nevertheless, they were affected by climate. Under dry sub-humid climate conditions, C stocks were 41.7 Mg ha(-1), 44% higher than under semi-arid climate (28.9 Mg ha(-1)), a result that reflects the effect of higher biomass production in wetter environments. Under slopes of 20-45%, C stocks were 54.3 Mg ha(-1), 172% higher than under slopes of 0-3% (19.9 Mg ha(-1)), because of the higher altitudes and wetter conditions under steeper slopes. Our results showed that areas under lower slopes have lower C stocks and lower aridity index. These drier conditions reduce the productive potential of annual crops and grasslands but enable the cultivation of high-yielding Crassulacean Acid Metabolism (CAM) crops, such as Agave spp, which have a high potential for biofuel production. Furthermore, the possibility of reintroducing organic residues from ethanol production can promote an increase in C stocks, contributing to climate change mitigation. Ultimately, our study provides insights from a holistic view of SOC accumulation drivers, supporting land use planning of highly sensitive environments in tropical drylands around the world. (AU)

• Processo FAPESP: 23/11337-8 - Efeito da mudança de uso da terra e das práticas de manejo da cana-de-açúcar no C do solo, na saúde do solo e nos serviços ecossistêmicos associados: uma síntese de evidências
• Beneficiário: Carlos Roberto Pinheiro Junior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 23/08814-9 - MONS: Mecanismos de emissão de óxido nitroso em solo tropical
• Beneficiário: Lucas Pecci Canisares
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 23/00438-8 - Sequestro de carbono do solo em sistemas agrícolas integrados no semiárido Brasileiro
• Beneficiário: Lucas Tadeu Greschuk
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 21/10573-4 - Centro de Pesquisa de Carbono em Agricultura Tropical (CCARBON)
• Beneficiário: Carlos Eduardo Pellegrino Cerri
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs