Microbe-mediated nutrient cycling and crop growth under long-term silicate fertilizer addition to paddy soils

Abstract

Silicate fertilizer promotes the growth and yield of rice, but its effects on soil microorganisms and their capacity to recycle nutrients and produce phytohormones, antioxidants and antimicrobial compounds remain largely unknown. We used Illumina sequencing and GeoChip to quantify the effects of long-term (30 year) silicate fertilizer application on microbial functional gene profiles for nutrient cycling (C, N and P) and production of phytohormones (ethylene, auxin, gibberellins and polyamines), antioxidants (catalase, peroxidase and superoxide dismutase) and antimicrobial compounds (hydrogen cyanide synthase and siderophores) in paddy soils. Long-term silicate fertilizer amendment increased the relative abundance of genes involved in (i) C fixation (RuBisCo and CODH) and the degradation of labile C (starch, hemicelluloses, and cellulose), but not recalcitrant C (pectin, chitin, and lignin), (ii) ammonification (ureC), N2O reductase (nosZ) and anammox (hzo), but reduced the relative abundance of genes involved in nitrification (hao) and denitrification (narG, nirK), (iii) mineralization of organic P (phoA, phoB and phy) and solubilization of inorganic P (ppx, ppk and gcd), but not genes involved in P uptake and transport and the response to P starvation, and (iv) the production of hydrocyanic acid (hcnB), but not genes responsible for the production of phytohormones and antioxidants. Prolonged application of silicate fertilizer therefore promotes the growth and yield of rice by altering microbial functional genes involved in nutrient cycling and the production of hydrocyanic acid. © 2025 Elsevier B.V.