The response patterns of r- and K-strategist bacteria to long-term organic and inorganic fertilization regimes within the microbial food web are closely linked to rice production.

ABSTRACT

Soil microbial food web is crucial for maintaining crop production, while its community structure varies among fertilization regimes. Currently, the mechanistic understanding of the relationships between microbial food web and crop production under various nutrient fertilizations is poor. This knowledge gap limits our capacity to achieve precision agriculture for ensuring yield stability. In this study, we investigated the abiotic (i.e., soil chemical properties) and biotic factors (i.e., microbial food web, including bacteria, fungi, archaea and nematodes) that were closely associated with rice (Oryza sativa L.) production, using soils from seven fertilization regimes in distinct sampling locations (i.e., bulk vs rhizosphere soil) at a long-term experimental site. Organic manure alone fertilization (M) and integrated fertilization (NPKM) combining manure with inorganic fertilizers increased soil pH by 0.21-0.41 units and organic carbon content by 49.1 %-65.2 % relative to the non-fertilization (CK), which was distinct with inorganic fertilization. The principal coordinate analysis (PCoA) revealed that soil microbial and nematode communities were primarily shaped by fertilization rather than sampling locations. Organic fertilization (M, NPKM) increased the relative abundance of both r-strategist bacteria, specific taxa within the fungal (i.e., Pezizales) and nematode communities (i.e., omnivores-predators), whereas inorganic fertilization increased K-strategist bacteria abundances relative to the CK. Correspondingly, network analysis showed that the keystone taxa in the amplicon sequence variants (ASVs) enriched by organic manure and inorganic fertilization were mainly affiliated with r- and K-strategist bacteria, respectively. Structural equation modeling (SEM) analysis found that r- and K-strategist bacteria were positively correlated with rice production under organic and inorganic fertilization, respectively. Our results demonstrate that the response patterns of r/K-strategists to nutrient fertilization largely regulate rice yield, suggesting that the enhanced soil fertility and r-strategists contribute to the highest crop production in NPKM fertilization.