Abstract
Eroded black soils (classified as Mollisols) lead to a thinner topsoil layer, reduced organic carbon storage and declined crop productivity. Understanding the changes in soil microbial communities owing to soil erosion is of vital importance as soil microbial communities are sensitive indicators of soil condition and are essential in soil nutrient cycling. This study used the reconstructed facility with 10, 20 and 30 cm topsoil thickness under no-till soya bean–corn rotation in black soil region of Northeast China. Illumina MiSeq sequencing targeting 16S rRNA, qPCR and soil respiration measurement were performed to assess the changes in soya bean and corn rhizosphere bacterial communities, as well as their abundance and activities due to the topsoil thickness. The results showed that soil bacterial communities from both soya bean and corn were more sensitive to topsoil removal than to soil biogeochemical characteristics. Topsoil depths significantly influenced both soya bean and corn bacterial communities, while they only significantly influenced the bacterial abundance and respiration in corn. We also found that the topsoil depths significantly induced the changes in phyla and genera from both soya bean and corn rhizosphere bacterial community, which aid further understandings on how topsoil layer influences the global nutrient cycling of Mollisols by influencing the change in microbial communities.
Highlights
The degradation of soil by erosion is a threat worldwide due to its negative effects on the environment and crop productivity [1]
We found that the topsoil depths significantly induced the changes in phyla and genera from both soya bean and corn rhizosphere bacterial community, which aid further understandings on how topsoil layer influences the global nutrient cycling of Mollisols by influencing the change in microbial communities
The higher sensitivity of corn to soil erosion was confirmed by Sui et al [12,26], who investigated the effect of topsoil removal on grain yield in the same zone and reported that crop yields declined with increased depth of topsoil removal and the yield reduction in corn was greater than in soya bean
Summary
The degradation of soil by erosion is a threat worldwide due to its negative effects on the environment and crop productivity [1]. The history of agricultural cultivation in this region dates back only 100 years, this region suffers from serious soil degradation problem, especially soil erosion, which decreases the thickness of humus horizon layer from 60–100 cm to 20–40 cm, as well as the decline of soil nutrient level or soil biophysico-chemical properties, such as soil organic matter content, microbial activities and soil water storage capacity [3,4,5] These changes directly influence the growth of plant root system and rhizosphere environment, reduce soil productivity and increase the cost of chemical input as a result, which definitely induce adverse effects in the sustainable development of agriculture food security in this region
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