Effect of Continuous Use of Fertilizers and Manures on Nutrient Uptake, Use Efficiency and Yield in Rice-Rice Cropping Systems

Long-term balanced fertilization integrating chemical fertilizers with organic manures is essential for maintaining high rice yields and soil health in intensive rice–rice cropping systems. This study assessed the impact of prolonged application of different fertilizer treatment including 50%, 100%, and 150% recommended NPK doses, combined with farmyard manure (FYM), micronutrients zinc (Zn) and sulfur (S) and an unfertilized control since inception of the experimental cite. The 100% NPK and 150% NPK rates corresponded to approximately 120:60:40 and 180:90:60 kg ha⁻¹ of N, P, and K, respectively. Results showed that 150% NPK (Kharif-7422 kg ha⁻¹ and rabi – 7959 kg ha⁻¹) and 100% NPK + FYM (Kharif-7214 kg ha⁻¹ and rabi – 8023 kg ha⁻¹) treatments significantly enhanced grain yields, surpassing other treatments. The combined FYM and NPK treatment also improved soil properties, increasing soil organic carbon and reducing bulk density over time, thereby sustaining soil fertility. Micronutrient additions of Zn and S improved yields compared to NPK alone but did not exceed the gains from 150% NPK, suggesting that macro nutrient sufficiency is more critical for yield maximization in this system. Consistent patterns of enhanced N, P, and K uptake were observed across both seasons, with nutrient uptake positively correlated with yield. SPAD chlorophyll readings at key growth stages (30, 60, 90 DAT) showed strong positive correlation with final grain yield, particularly under integrated treatments, reflecting improved nitrogen nutrition and photosynthesis efficiency. Overall, the study confirms that integrated nutrient management with optimum macro- and micronutrient application plus organic amendments maximizes yield and nutrient use efficiency, securing sustainable rice production in Indian agroecosystems.