| In order to further explore the effects of reduced fertilization and water level on double cropping rice yield,soil nutrients and nitrogen and phosphorus loss in paddy fields,and to provide technical support for reducing fertilization and water level management in rice areas in Anhui Province,a field experiment was conducted in the main rice producing area of Chaohu Lake Basin in Anhui Province in 2019.A total of 9 treatment Settings were set: high(15cm),medium(10cm)and low(5cm)water levels,with 3 replicates;Three fertilization measures were set for each water level,which were conventional fertilization(according to the amount of fertilizer applied when the local grain yield project reached the optimal economic yield),reduced fertilization(20% reduction of N,P and K fertilization on the basis of conventional fertilization treatment),and blank fertilization(no fertilization).In the same year,a research experiment on the characteristics of nitrogen and phosphorus loss in the field ditch pond was conducted near the plot test.In this experiment,a field surface water sampling monitoring point was set in the field near the drainage ditch in Chaohu experimental base,and mixed samples were collected in different regions.When the ecological ditches are legally monitored by cross-section concentration,water samples from each cross-section are taken to measure nitrogen and phosphorus,and a cross-section is set at intervals of a certain length.Sampling points were set up near the entrance of Chao Lake to collect water samples.Finally,the interception effect of Tianggou Pond on nitrogen and phosphorus loss in the paddy field was analyzed.The following conclusions:(1)This study found that under the condition of same water level,compared with conventional fertilization,quantitative fertilization(on the basis of conventional fertilizer NPK minus 20%)did not reduce rice production,at the same time stem tillers Numbers per spike,plant height,no significant difference with conventional fertilization and different water depth(5 cm,to 10 cm,15 cm)had no significant effect on rice yield,including 10 cm depth rice yield effect is better than that of the rest of the two levels,the difference was not significant.(2)Paddy field under different water conditions,fertilization of soil organic matter content were higher than conventional fertilization and quantity-reducing no fertilizer treatment,reduction fertilization will not reduce the soil nutrient content,at the same time in the water level(10 cm)reduction under the condition of fertilization on the premise of guarantee high rice can improve soil organic matter,total nitrogen,available nutrient content better effects of improving soil fertility.(3)Decrement fertilization can ensure high and reduce of rice field water concentration of nitrogen and phosphorus,reduce the risk of loss,in chaohu lake basin was water depth of 10 cm + reduction fertilization can ensure that rice yield and fertilizer of soil at the same time,reduce the risk of loss of nitrogen and phosphorus.(4)Regarding the interception effect of different ecological ditches on the loss of nitrogen and phosphorus,the experimental study found that natural ecological ditches have a certain degree of interception effect on the inflow of nitrogen and phosphorus polluted water.Further,the magnitude of the interception effect of different ditches on nitrogen and phosphorus was related to time,rainfall,depth of ditches,slope and ecological structure of ditches.Under the experimental conditions,the interception rates of total nitrogen,ammonium nitrogen,nitrate nitrogen,total phosphorus and soluble phosphorus in a series of ditches were 85.76 %,69.69 %,82.45 %,57.81 % and 62.57 %,respectively.The intercept effect is obvious. |
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