Straw Retention and Manure Application Increase the Yield of Rice in Rotation With Rapeseed and Wheat by Improving Soil Fertility

Crop rotation alters soil properties, influencing nutrient availability and plant growth. However, the influence of preceding crops on rice yield is not fully understood, particularly regarding their interaction with fertilization. Here, a seven‐year field experiment was conducted to ascertain the fertilization effects on rice yield under rice–rapeseed (RR) and rice–wheat (RW) rotation. Treatments were established using no fertilizer (control), chemical fertilizer (F), chemical fertilizer with straw retention (FS), and organic manure substituting 20% chemical fertilizer (FM). Results showed that fertilization significantly increased rice yield compared to the control (p < 0.05). Rice yield under RW (by 37.6%–48.9%) was more dependent on fertilizer inputs than under RR (by 29.0%–37.3%). Fertilization also improved the proportion of soil macroaggregates (> 0.25 mm) and associated carbon (C) and nitrogen (N) storage. RR soils showed greater C and N storage in macroaggregates with FS compared to FM, and the opposite pattern was observed in RW soils. Except for β‐glucosidase and cellulase, soil extracellular enzymes involved in nutrition cycling exhibited their highest activities with FM. Random forest analysis revealed that soil enzyme activities and macroaggregate‐associated C and N storage were key determinants of rice yield, with limited relevance of small macroaggregates under RW compared to RR. These findings indicate that preceding crops shape rice yield responses to fertilization by modifying soil fertility. When combined with chemical fertilizer, straw retention under RR and manure application under RW are effective practices for maximizing rice productivity.