Dados do Trabalho

Título

FUNCTIONAL GENES RELATED TO NITROGEN AND PHOSPHORUS CYCLING IN A DESERTIFICATION GRADIENT

Resumo

The practice of grazing exclusion has been applied to soil conservation, particularly in semiarid regions such as the Caatinga biome. However, it is unclear whether grazing exclusion reduces the negative effects of overgrazing on functional genes related to nutrient cycles such as nitrogen and phosphorus. The decrease in soil functional capacity caused by degradation is mainly due to the loss of ecological processes carried out by microbial communities. Therefore, evaluating the ecological functions of soil microbial communities is essential to understand the long-term impacts of anthropogenic actions on soil systems. However, there is still a lack of information on how degradation can alter ecological processes, such as nitrogen (N) and phosphorus (P) cycling. The study was conducted in Irauçuba, Ceará, Brazil (3º44′ 46"S e 39º47’00"W). Quantitative PCR (qPCR) was performed to enumerate copies of functional genes involved in soil phosphorus and nitrogen cycling (phoD, amoA [archaea and bacteria], nifH, nirK, nirS, and nosZ), we also quantified the alkaline phosphatase. The results revealed differences (p < 0.05) in the abundance of all evaluated genes between the three areas. The disturbances caused by the degradation promoted an imbalance in the N cycle, indicating that degraded soils are not a receptive environment to the accumulation of N in the soil. There was a reduction (p < 0.05) of the enzyme alkaline phosphatase and the abundance of the phoD gene, reducing the potential for P mineralization. The results showed that the restoration improved the soil properties, highlighting the potential of grazing exclusion as a restoration strategy for degraded soils in the Caatinga biome. This study provided important insights into the impacts of degradation on soil microbial functions and the potential of grazing exclusion as a restoration strategy.

Palavras-chave

Soil functions, Microbial ecology, N and P cycles, Drylands.

Instituição financiadora

FAPESP (São Paulo Research Foundation) - (2021/14418-3 and 2022/07117-0)