Evaluation of a subtropical maize-rice rotation system maintained under long-term fertilizer inputs for sustainable intensification of agriculture

The impacts of long-term (1996-2019) fertilizer inputs on grain yield and edaphic factors of upland maize and wetland rice rotation system were assessed for sustainable intensification of agriculture. Subtropical field treatments included swine manure compost (CP), chemical fertilizer (CF, control), no fertilizer (CK, blank), inorganic N-amended CP (CPN1 and CPN2), peat (PN1) and green manure (GMN1). Maize exhibited a significantly increased yield trend under CF, GMN1 and CP-based inputs (CP, CPN1 and CPN2), whereas rice yield displayed a non-significant marginal improvement or negative result. Principal component analysis of edaphic factors revealed distinct clustering of CP-CPN1-CPN2, CF-GMN1-CK and PN1 samples during maize-rice rotation. CP-based inputs in particular improved OM, EC, microbial metabolism and nutrient availability during crop rotation. Pronounced soil microbial activity and Bacterial abundances were recorded during maize cultivation. In contrast, low aerobic metabolism coupled with high Bacterial and Archaeal species richness, diversity and evenness were found during rice cultivation. In conclusion, increasing maize yield trends observed under longterm CP-based inputs were on par with CF and GMN1 amendments that concurrently acidified soil. Numerically dominant aerobic Bacteria appear to drive nutrient recycling and promote maize grain yield, whereas metabolically lethargic diverse prokaryotes constrained nutrient turnover stagnating the rice yield.