| 【Object】To utilize the limited phosphate ore resources more rationally, clarify the utilization rate of phosphatic fertilizer for paddy rice under the drip irrigation conditions; research into the influence of phosphatic fertilizer operation on the soil phosphorus transformation, distribution and phosphatic fertilizer utilization rate of paddy rice field with the drip irrigation. This project is designed to explore and discuss the migration law of the soil phosphorus of different ratios of base and topdressing of phosphatic fertilizer in the paddy rice field with the drip irrigation; expound on the influence of phosphatic fertilizer operation under different drip irrigation conditions on the soil phosphorus transformation and distribution, and the utilization rate of phosphatic fertilizer for paddy rice; to provide theoretical bases for the improvement of the utilization rate of the phosphatic fertilizer.【Method】Based on ratios of base and topdressing of phosphatic fertilizer, five treatments were set for the phosphatic fertilizer input, namely CK(without phosphatic fertilizer), T1 full basal application, T2 30% basal application+70% drops, T3 70% basal application+30% drops and T4 full drop. The total fertilizer input of each treatment was set the same, the nitrogenous fertilizer(pure nitrogen) was 270kg/hm2, the phosphatic fertilizer(P2O5) was 90 kg/hm2, the potash fertilizer(K2O) was 60 kg/hm2, all the potash fertilizer were used for base fertilizing, the nitrogenous fertilizer and the rest of phosphatic fertilizer were fertilized eight times with drip irrigation in ratios. The paddy rice species for test was T-04. Through investigating into the dynamic trend of the dry matter accumulated in different stages of growth and development, the yield factors during the harvest period and the actual yield were studied to explore the influence of phosphatic fertilizer operation on the phosphorus nutrition for paddy rice and the utilization rate of phosphatic fertilizer. The soil samples were collected in different fertilization periods and from different soil areas to study the influence of phosphatic fertilizer operation on the transformation and distribution of soil phosphorus.【Results】1. The full basal application of phosphatic fertilizer can significantly increase the content of 0~5cm Resin-P and Na HCO3-P under the dropper. Under the condition of full basal application and 30% basal application of phosphatic fertilizer, the content of Na OH-P under the dropper decreased rapidly under the dropper with the increase of soil depth; Under the condition of the small basal application percentage and without the basal application treatment, the content of HCl-P in various soil layers is higher than that elsewhere; while the content of the residue-P was close to each other and remained stable in various layers of soil, and increased with the decrease of the basal application percentage. 2. Under the CK treatment, the content of Na OH-P, HCl-P and residue-P was relatively high, while the content of Resin-P and Na HCO3-P was relatively low. Under the T1 treatment, the content of Resin-P and Na HCO3-P was relatively high, while the content of Na OH-P, HCl-P was relatively low. Under the T2 treatment, the content of residue-P was relatively high, while the content of Resin-P Na HCO3-P and Na OH-P was relatively low. The content of HCl-P was relatively high only under the T4 treatment. The content of other components under the T3 treatment was similar to that under the CK and T1 treatment. 3. The output of the dry matters with the application of phosphatic fertilizer during the three investigation and sampling periods was higher than that without the phosphatic fertilizer treatment. The output of the dry matters under the phosphatic fertilizer application of 30% basal application and the 70% basal application reached the maximum. The similar trend also appeared in terms of the number of productive ears, kernels per spike, grains, maturing rate and thousand seed weight. 4. Under the fertilizer application model of 30% basal application and the 70% basal application, the phosphatic fertilizer utilization rate, partial factor productivity and agricultural utilization efficiency reached 28.5%, 89.5kg/kg and 8.0743kg/kg, respectively, which were all higher than those under the other treatments. 5. The phosphorus content of grains and the economic output were significantly positively related to each other. The phosphorus content of grains was also significantly positively related to the fertilizer utilization rate and the biological output., respectively. The phosphorus content of stalks was significantly positively related to the economic output and the biological output. The phosphorus content of plants was extremely significantly positively related to the fertilizer utilization rate, economic output, and biological output. However, the phosphorus content of plants was negatively related to the partial factor productivity. The phosphorus content of plants was also significantly positively related to the agricultural utilization rate. 6. During the soil layer of 0~40cm, the content of Resin-P was significantly positively related to the phosphorus content of grains and stalks and the phosphorus absorption amount of plants. Na HCO3-P and the phosphorus content of grains during the soil layer of 0~40cm were positively related to each other, but the correlation was not significant, while the former was significantly positively related to the phosphorus content of stalks and the phosphorus absorption amount of plants. Na OH-P was extremely significantly negatively related to the phosphorus content of grains during the soil layer of 0~20cm, the phosphorus absorption amount of plants and the phosphorus content of grains during the soil layer of 20~40cm.【Conclusion】1. The proper ratio of basal phosphorus fertilizer and top-dressing is an approach to achieve the components of the ultimate output and the proper output; 2. The increase of the output and the utilization rate of the phosphatic fertilizer is closely related to the phosphorus absorption content. Under the high-frequency irrigation condition, proper operation based on the phosphorus demand characteristics of paddy rice can achieve the efficient utilization of phosphorus resources and the increase of the output; 3. By adopting the agronomic measures, the fertilizer regime and the irrigation system based on the local conditions, the content of Resin-P and Na HCO3-P can be increased, and the transformation of phosphorus form to Na OH-P can be reduced, and the phosphorus absorption and utilization rate of plants can be improved... |
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