Abstract
Plant-derived carbon (C) is considered fundamental to understand the interaction between rhizosphere microbes and plants in terrestrial ecosystems. Biochar soil amendment may enhance plant performance via changing soil properties or microbial diversity in the rhizosphere. However, our knowledge of how plant-microbiome associations respond to biochar amendment remains rather limited. Herein, 13CO2 steady-state labeling combined with DNA stable-isotope probing was used to characterize soil bacterial communities in the rhizosphere contributing to the utilization of plant-derived C. The diversity of bacteria active in the utilization of root exudates was determined after biochar amendment in a legume-based intercropping system (Vicia faba L., with Zea mays L.). The results showed the biochar application not only changed the bacterial community structure and diversity in the rhizosphere, but also altered bacterial members actively assimilating plant-derived C. There were more labeled species in the biochar-amended soils than the control soils. Compared with the control, the biochar amendment increased the relative abundances of Firmicutes and Bacteroidetes members (i.e., Bacillus, Clostridium, Sporomusa, Desulfosporosinus, and Alicyclobacillus) while decreasing the abundances of Proteobacteria members (e.g., Methylobacterium and Sphingomonas) utilizing plant-derived C. In contrast, slow-growing species of the phyla Acidobacteria, Planctomycetes, and Gemmatimonadetes were barely labeled. The bacteria found stimulated by the biochar amendment are known for their ability to fix nitrogen, solubilize phosphorus, or reduce iron and sulfur, which may potentially contribute to the “biochar effect” in the rhizosphere. This study is the first to provide empirical evidence that biochar amendment can alter the soil bacterial community assimilating plant-derived C; this may have consequences for nutrient cycling and improving plant performance in intercropping systems.
Highlights
Modern agricultural systems provide high crop yields, but they generate serious impacts on the environmental
Compared with the control treatment, significantly higher (P < 0.05) C/N ratio was found in the biochar amendment soils (Table 1)
Relatively high soil pH, Olsen-P, NH4+, and NO3− contents were detected in the biochar treatment, none of these values were significantly different compared with the control treatment
Summary
Modern agricultural systems provide high crop yields, but they generate serious impacts on the environmental. Intercropping is an ancient and traditional agricultural practice, and especially legumebased intercropping systems have great potential for contributing to agricultural productivity through increasing nitrogen (N) inputs and phosphorous (P) bioavailability (Rose et al, 2015; Tang et al, 2016) in the terrestrial system. In this regard, an intercropping system provides a way to introduce soil available nutrients into the agro-ecosystem, avoiding the excessive use of fertilizers and pesticides relied upon during conventional cultivation. An improved understanding of nutrient cycling in intercropping systems may offer new insights into achieving long-term agricultural productivity
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