Soil microbial community structure affected by biochar and fertilizer sources

Authors: Rana Dangi, Sadikshya; Gao, Suduan; Wang, Dong

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2019
Publication Date: 11/19/2019
Citation: Rana Dangi, S., Gao, S., Wang, D. 2019. Soil microbial community structure affected by biochar and fertilizer sources. Applied Soil Ecology. 150. Article 103452. https://doi.org/10.1016/j.apsoil.2019.103452.
DOI: https://doi.org/10.1016/j.apsoil.2019.103452

Interpretive Summary: Intensive use of chemical fertilizers has led to deterioration of soil and environmental quality, and combination with organic fertilizers or biochar amendments can potentially mitigate the harmful effects of chemical fertilizers by improving soil health. This study evaluated the effects of an animal-waste based organic fertilizer in various combinations with chemical fertilizer and amendment with biochar on soil microbial communities and chemical properties after two growing seasons of serrano chili peppers. Results clearly showed that both incorporation of organic fertilizer and amendment with biochar significantly increased beneficial microbial communities. Chemical fertilizer significantly decreased the populations of beneficial microbial communities compared to unfertilized soil. Thus, addition of organic fertilizers or biochar amendments can promote soil health and improve sustainability for conventional farming systems.

Technical Abstract: Use of organic fertilizer or organic amendments such as biochar can potentially mitigate the deleterious environmental impacts of inorganic fertilizers in agroecosystems but their specific effects on soil microbial communities have not been well defined. The aim of this research was to evaluate an incorporation of poultry-waste based organic fertilizer in various combinations of inorganic fertilizer and amendment with biochar on soil microbial communities and chemical properties after two growing seasons of serrano chili peppers. Treatments included combinations of inorganic N with different rates (0%, 50%, 75% and 100% of total N supply) of organic N (org-N) and inorganic N with amendment of three rates (10, 30 and 50 t ha-1) of a coconut shell biochar. After two years of application, the amounts of total, arbuscular mycorrhizal fungal (AMF), and Gram positive and Gram negative bacterial phospholipid fatty acid (PLFA) increased significantly at the higher rates of biochar compared to those at lower rates, unfertilized, and non-amended soil. However, significant differences were not observed for fungal PLFA between inorganic N with biochar and those without addition of biochar. Organic N application also increased (with the highest from 75% rate) the amounts of total, Gram positive and Gram negative bacterial, AMF, and actinomycetes PLFAs compared to unfertilized and inorganic N treatments, but the amounts of fungal PLFA significantly decreased as biochar application rate increased. The neutral lipid fatty acid (NLFA) analysis clearly showed that inorganic fertilizer alone or low rate of biochar amendment significantly decreased the amount of AMF compared to unfertilized soil. All results indicate that soil amendment with biochar or incorporation of organic fertilizer for about two years significantly increased microbial community biomass and composition. Thus, in conventional farming that uses mostly inorganic fertilizers, the combined use of inorganic fertilizers with org-N source or organic amendment with biochar can improve soil health and agricultural sustainability.