Effects Of Phosphate Fertilizer Reduction On Rice Yield And Phosphorus Loss In Double-cropping Rice

Excessive application of phosphate fertilizer results in large amount of phosphorus leaching into water body through surface runoff or underground,which causes agricultural non-point source pollution such as eutrophication.In order to develop a phosphorus fertilizer application technology suitable for reducing pollution and high yield of double-cropping rice in Hunan Province.There were six treatments including no phosphorus control(CK),conventional fertilization,superphosphate fertilizer(CF1),conventional fertilization,calcium magnesium phosphate fertilizer(CF2),reduction of 10% superphosphate fertilizer(T1),reduction of 20% superphosphate fertilizer(T2),and reduction of 30% superphosphate fertilizer(T3)in this long-term experiment.The experiment aim at study the effects of different phosphorus fertilizer reduction modes on phosphorus runoff loss and leaching loss,rice yield and phosphorus fertilizer utilization rate of double-cropping rice field in Hunan Province.The results are as follows :1)The concentrations and losses of total phosphorus(TP),water-soluble phosphorus(DP)and particulate phosphorus(PP)in paddy runoff increased with the increase of phosphorus fertilizer application amount.The farther away from phosphorus fertilizer application time,the concentrations of TP,DP and PP in runoff decreased gradually.Reduction of 10%～30% phosphorus fertilizer can significantly reduce phosphorus runoff loss.Compared with the TP runoff losses of CF1 treatment,the TP runoff losses of T1,T2 and T3 treatments respectively decreased by 25.84%,32.21% and 44.78% in early rice,and those of T1,T2 and T3 treatments in late rice respectively decreased by 41.96%,42.35% and 25.88%.The DP runoff loss of phosphorus in early and late rice respectively accounted for 20.64%～34.00%and 21.16%～ 33.76% of TP runoff loss.The phosphorus runoff in paddy field was mainly PP.2)Reduction of 10%～30% phosphorus fertilizer can reduce the leaching loss concentrations of phosphorus.The TP leaching loss concentrations decreased with the decrease of phosphorus fertilizer application amount,and the TP leaching loss concentrations decreased with the deepening of soil.Compared with those of CF1 treatment,the TP leaching concentrations of T1,T2 and T3 treatments in early and late rice at 0～20 cm of soil respectively decreased by 29.77%～52.24% and 20.35%～37.61%,at 20～40cm of soil respectively decreased by 28.19%～39.19% and 13.49%～40.41%,at 40～60cm of soil respectively decreased by 46.78%～63.52% and 13.49%～40.41%,at 60～80cm of soil respectively decreased by 20.19%～34.97% and 45.87%～72.32%,at 80～100cm of soil respectively decreased by 20.35%～37.61% and 45.15%～59.84%.3)Reduced 10%～30% phosphorus fertilizer can reduce the leaching losses of phosphorus.The TP leaching losses at 40～60 cm of soil of T1,T2 and T3 treatments in early and late rice respectively were 0.47%～0.64% and 0.32%～0.64% lower than those in CF1.The PP leaching losses of T1,T2 and T3 treatments in early and late rice respectively accounted for 19.71%～35.61% and 25.47%～30.43% of TP leaching loss.DP was the main leaching loss in rice field.4)The grain yields of early rice under T1 and T2 treatments respectively increased by10.77% and 1.64% compared with that under CF1 treatment,and decreased by 3.74% under T3 treatment.The grain yield of late rice under T1 treatment increased by 5.12% compared with CF1 treatment,and the grain yield of T2 and T3 treatments decreased by 3.68% and7.73%.5)The agronomic utilization rate,absorption utilization rate and partial productivity of phosphorus fertilizer were respectively improved by 35.98%～76.82,28.93%～42.15% and23.08%～42.10% in early rice,and were respectively improved by 28.54%～37.68%,39.50%～47.84% and 15.27%～41.61% in late rice.6)The application of phosphorus fertilizer reduced runoff loss and leaching loss while ensuring rice yield and quality,and improved phosphorus absorption and utilization rate.Therefore,from the perspective of agricultural sustainable development and grain yield protection,the 10% reduction of phosphorus fertilizer fertilization mode can reduce agricultural non-point source pollution and improve the utilization rate of phosphorus fertilizer in Liuyang City,Hunan Province.