Effects of combined biochemical inhibitors and fertilization models on nutrient uptake and use efficiency of rice in yellow clayey field

Application of biochemical inhibitors for urease and nitrification is an effective way of improving fertilizer use efficiency of rice. The objective of this study was to determine the characteristics of nutrient use of rice as affected by biochemical inhibitors and fertilization models, and find the optimal yield and efficient application method in rice growing region in yellow clayey soils. It analyzed the interaction effects of biochemical inhibitorsurease inhibitors N-(n-butyl) thiophosphoric triamide (NBPT and N-(n-propyl) thiophosphoric triamide (NPPT), and nitrification inhibitor 2-chloro-6-(trichloromethyl) pyridine (CP) with fertilization models (one-off and three-time fertilizations) on nutrient absorption, utilization and distribution of rice, and the relationship between nutrient uptake and grain yield using two factor randomized block design. Results showed that certain interaction effects was observed between inhibitor combination and fertilization model on the uptake, utilization and distribution of nitrogen (N), phosphorus (P) and potassium (K) at the main growth periods of rice. The three times urea fertilization treatment significantly increased N, P and K uptake (respectively by 11.0%, 0.9% and 4.2%) at maturity, and N recovery efficiency and N agronomic efficiency (respectively by 27.5% and 70.8%) over those of one-off urea fertilization treatment. The addition of inhibitors (NBPT, NPPT/+CP) significantly increased N, P and K uptakes of rice, dry matter production and N accumulation after heading stage. It also improved the allocation of nutrients in grain and N use efficiency under different fertilization models. The application of new urease inhibitor NPPT alone or combined with CP had the similar effect on nutrient uptake and use in paddy fields with NBPT. The uptake of N, P and K of rice at maturity had significant positive correlation with grain yield under different fertilization models. In conclusion, the integration and optimization of fertilization techniques combined with inhibitors enhanced the uptake and transport of N, P and K after heading stage. It also promoted nutrient accumulation and at the same time significantly improved rice yield and nutrient use efficiency in yellow clayey fields.