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Silva, Danilo F. ; Cardoso, Elke J. B. N. ; Huang, Laibin ; Erikson, Christian ; Silva, Antonio M. M. ; Araujo, Victor L. V. P. ; Silva, Davila E. O. ; Melo, Vania M. M. ; Araujo, Ademir S. F. ; Pereira, Arthur P. A. ; Rodrigues, Jorge L. Mazza

• Tipo de documento: Artigo Científico
• Fonte: APPLIED SOIL ECOLOGY; v. 196, p. 10-pg., 2024-02-01.

Resumo

There has been widespread application of grazing exclusion in soil conservation, particularly in semiarid regions. However, it is unclear how grazing exclusion reduces the negative effects of overgrazing on functional genes related to essential nutrient cycles, such as N and P, in the Caatinga biome. This study evaluated the impact of long-term overgrazing and grazing exclusion on the soil microbial functional pools related to N and P cycling compared to native Caatinga soil. There were significant variations in the abundance of functional genes across the three areas (p < 0.05). In the dry season, both native and restored areas showed notably higher copy numbers per gram of dry soil of nifH and nirK genes (ranging from 4.90E+05 to 6.86E+06) compared to the degraded area (ranging from 2.88E+05 to 1.97E+06). Copy numbers of archaeal amoA, nirS, and nosZ genes exhibited no significant variation among areas, except for bacterial amoA, which was higher in the native area (similar to 5.43E+05). Similar results were observed in the rainy season; however, nirS gene abundance was higher in the degraded area (similar to 1.38E+08), and nosZ showed higher abundance in the native area (similar to 3.37E+05). The high abundance of nosZ and nirS genes, coupled with the concurrent lower levels of amoA and nifH genes associated with nitrification and biological nitrogen fixation in areas under desertification, indicates an augmented denitrification activity. This suggests an escalated degradation of organic nitrogen, potentially leading to reduced availability of N inputs for soil organisms. Consequently, It may exacerbate N losses within the soil. Overall, these findings underscore a potential imbalance in the N cycle, particularly during the dry season. The results also substantiate that restoration improved the soil properties highlighting the potential of grazing exclusion as a restoration strategy for degraded soils in the Caatinga biome. (AU)

• Processo FAPESP: 22/07117-0 - Abundância de genes relacionados ao ciclo do fósforo no solo em um gradiente de desertificação
• Beneficiário: Danilo Ferreira da Silva
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Mestrado
• Processo FAPESP: 21/14418-3 - Estrutura da comunidade de fungos em um gradiente de desertificação no bioma Caatinga
• Beneficiário: Danilo Ferreira da Silva
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 16/18944-3 - Mudanças climáticas e eficiência energética na agricultura: um enfoque em estresse hídrico, manejo orgânico e biologia do solo
• Beneficiário: Elke Jurandy Bran Nogueira Cardoso
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático