Organic manure induced soil food web of microbes and nematodes drive soil organic matter under jackfruit planting

Abstract

Partial substitution of chemical fertilizers by organic manure is essential for improving the soil quality and crop production. However, there is limited information regarding the complex microbial-microfaunal interactions derived from different organic or inorganic fertilizer application rate in the rhizosphere of jackfruits. Therefore, the objective was to compare the effects of organic/inorganic fertilizers on the soil food web of microbes and nematodes. Filed and greenhouse studies were set up with six treatments, including CK (no fertilizer), 100CF (100% chemical fertilizer), 30OM (30% organic manure plus 70% chemical fertilizer), 50OM (50% organic manure plus 50% chemical fertilizer), 70OM (70% organic manure plus 30% chemical fertilizer) and 100OM (100% organic manure). After 4 years application of organic manure under field conditions, there was higher soil organic matter (SOM), microbial biomass carbon (MBC), nematode diversity and jackfruit yield. Moreover, the number of total nematode, microbivorous nematodes and omnivores-predators were positively correlated with organic manure, while plant-parasites did the opposite in greenhouse experiment. Organic manure increased the abundance, richness and Shannon diversity of bacteria and fungi as well as maturity indices (MI), Shannon index (H′), Pielou evenness index (J), enrichment index (EI), structural index (SI) and nematode channel ratio (NCR) of the nematode community in greenhouse experiment. Soil pH and SOM were significantly correlated with the variation of soil microbial-microfauna. Network analysis indicated that soil amended with organic manure presented more positive correlation between beneficial nematodes and microorganisms, but a negative correlation between plant-parasites Pratylenchus and dominant fungal taxon Chytridiomycota. These results indicated the feasibility of organic manure for soil quality improvement with high SOM and pH, suggesting that the correlation between microbes and nematodes constructed by organic fertilizer may play a key role in the improvement of soil quality.