Effects of aeolian deposition on soil properties and microbial carbon metabolism function in farmland of Songnen Plain, China.

The effects of wind erosion, one of the crucial causes of soil desertification in the world, on the terrestrial ecosystem are well known. However, ecosystem responses regarding soil microbial carbon metabolism to sand deposition caused by wind erosion, a crucial driver of biogeochemical cycles, remain largely unclear. In this study, we collected soil samples from typical aeolian deposition farmland in the Songnen Plain of China to evaluate the effects of sand deposition on soil properties, microbial communities, and carbon metabolism function. We also determined the reads number of carbon metabolism-related genes by high-throughput sequencing technologies and evaluated the association between sand deposition and them. The results showed that long-term sand deposition resulted in soil infertile, roughness, and dryness. The impacts of sand deposition on topsoil were more severe than on deep soil. The diversity of soil microbial communities was significantly reduced due to sand deposition. The relative abundances of Nitrobacteraceae, Burkholderiaceae, and Rhodanobacteraceae belonging to α-Proteobacteria significantly decreased, while the relative abundances of Streptomycetaceae and Geodermatophilaceae belonging to Actinobacteria increased. The results of the metagenomic analysis showed that the gene abundances of carbohydrate metabolism and carbohydrate-activity enzyme (GH and CBM) significantly decreased with the increase of sand deposition amount. The changes in soil microbial community structure and carbon metabolism decreased soil carbon emissions and carbon cycling in aeolian deposition farmland, which may be the essential reasons for land degradation in aeolian deposition farmland.

Effects of application of phosphate and phosphate-solubilizing bacteria on bacterial diversity and phosphorus fractions in a Phaeozems.

The aim of this study is to improve the utilization of phosphorus (P) in soil, and to study the effects of phosphate-solubilizing bacteria (PSB) on P fractions and bacterial communities. In this experiment, we reduced the amount of P fertilizer by 30 % and 40 % respectively to studied the effects of combined application of bacterial fertilizers on soil microbial community and phosphate transformation process under different fertilization rates. The results showed that the application of PSB affected the transformation process of different P fractions. PSB had the most significant impact on organic phosphorus (p < 0.05). Correlation analysis showed that the abundance of bacteria was significantly correlated to the P fractions, indicating that the application of PSB had affected the bacterial community structure. In addition, Structural Equation Model (SEM) analysis showed that there was a causal relationship between the various visual variables. SEM confirmed the response relationship between bacterial communities and P components. Based on these results, we concluded that the application of PSB increased the sensitivity of P components, especially Olsen-P and MBP, to soil microorganisms. The application of PSB is an effective method to improve P utilization.