Effects of Different Nutrient Management Regimes on Rice Yield and Nitrogen Uptake and Use Efficiency

(1) Background: We investigated the effects of nutrient levels on rice yield and nitrogen uptake, with the aim of improving rice yield and nitrogen use efficiency. (2) Methods: A 3-year field experiment was conducted using the rice variety Changliangyou Fuxiangzhan, with six treatments: no nitrogen application (CK), conventional fertilization (FP), single basal application of 60-day slow-release urea (CRU1), single basal application of urea combined with 40-day and 90-day slow-release urea (CRU2), partial substitution of chemical fertilizer with bio-organic manure (FPM), and conventional fertilization combined with straw return (FPS). (3) Results: Different nutrient management regimes significantly affected rice yield and nitrogen uptake and use, as well as soil nitrogen content. CRU2 achieved the highest performance across most indicators, with grain yield averaging 9.6% higher than that of FP and 36.4% higher than that of CK, alongside consistently greater effective panicle numbers. It also significantly enhanced nitrogen uptake, with higher grain and straw N accumulation, and showed the best nitrogen use efficiencies. Soil responses varied by treatment: FPS and FPM increased total nitrogen, while CRU2 and CRU1 had the highest inorganic nitrogen, and microbial biomass nitrogen peaked under FPM, CRU2, and FPS. Despite these benefits, CRU2 showed the largest negative nitrogen balance, averaging -33.0 kg ha^-1 over 3 years. (4) Conclusions: The CRU2 treatment achieved efficient synchronization between nitrogen supply and demand, with the highest yield, nitrogen uptake, and soil nitrogen levels.