Assessment of Native Am Fungi and Soil Microbial Communities Through Phospholipid Fatty Acid Profiling Under Different Nutrient Management Practices of a Long-Term Soybean-Wheat and Chickpea-Based Cropping System

In this study, we identified the role of native arbuscular mycorrhizal fungi (AMF) on changes in soil microbial communities, microbial ratios and soybean yield assessed in a long term (12 years) soybean-wheat (SW) and soybean-chickpea (SC) rotation trial managed with   organic, inorganic and integrated nutrient management practices in Vertisols of Central India. The phospholipid fatty acid (PLFA) biomarkers for Gram-positive and Gram-negative bacteria, fungi, anaerobes, actinomycetes and eukaryotes, fungi/bacteria ratio, Gram-positive/Gram-negative ratio, total PLFA were examined. The potential of various practises based on PLFA profiling and yield were compared to scores obtained through principal component analysis, which identified situations with abundant soil microbial communities. It was found that the total PLFA declined due to continuous inorganic fertilization. Regardless of the cropping system, the total PLFA in the organic treatment was 48.94% and 50.22% greater than inorganic and integrated practices, respectively. However, PLFA microbial communities were relatively more abundant in the SW as compared to SC. Nutrient management systems particularly organic system exerted significant influences on microbial community and showed general pattern (organic> integrated > inorganic and SW> SC) with practices followed. With regards to yield, SW recorded a 36.67% higher yield than SC and SW-Org. seemed to be responsible for the discrimination of the soil microbial communities against all the other treatments. In SW-Org recorded higher abundance in AM. PLFA (3.32 nanomoles PLFA g -1 ) AM. NLFA (38.83 nanomoles PLFA g -1 ), fungi (1.14 nanomoles PLFA g -1 ), eukaryotes (62.20 nanomoles PLFA g -1 ), actinomycetes (7.40 nanomoles PLFA g -1 ), anaerobes (11.93 nanomoles PLFA g -1 ), Gram-positive (65.23 nanomoles PLFA g -1 ) and Gram- negative (30.63 nanomoles PLFA g -1 ), total PLFA (209.83 nanomoles PLFA g -1 ) and yield (1329 kg ha -1 ). The biomarkers of all the microbial groups were significantly and positively correlated with each other and with total PLFA ( p < 0.05). Out of all the PLFA biomarkers, AM. NLFA and fungi/bacteria ratios were significantly associated with yield ( p < 0.05). These findings suggest that growing soybean in rotation wheat under organic management practices results in the development of specific soil microbial communities that increase microbial biomass, enhance soil health and boost productivity.