| In traditional rice production,there are problems such as sloppy water and fertilizer management,"big water and big fertilizer",which not only reduces the efficiency of water and fertilizer utilization and causes waste of agricultural resources,but also causes a series of environmental problems.Therefore,it is of strategic importance to develop water-saving irrigation technology and optimize nitrogen fertilizer management mode to achieve efficient coupling of rice water and nitrogen for sustainable agricultural production.Controlled-release urea has been shown to have high yield increase potential and resource utilization efficiency,but its application in agricultural production is limited due to its high production cost.The water-saving benefits of alternating wet and dry irrigation in rice production have been widely used,but there are still gaps in the research on the combination of different fertilizer types on rice yield and water and nitrogen use efficiency under alternating wet and dry irrigation.Therefore,in 2021 and 2022,this study carried out community experiments in the Agricultural Meteorological Experimental Station of Jingzhou District,Jingzhou City,Hubei Province,using"Super Rice-Liangyou152"and"Hubei Zao 18"as materials,adopting a split-zone design,irrigation method set up conventional irrigation（CF）and dry and wet alternating irrigation（AWD）2 kinds,nitrogen fertilizer application mode set 100%conventional fast-acting urea（N1）,60%controlled-release urea+40%conventional fast-acting urea（N2）and 100%controlled-release urea（N3）3 kinds.The nitrogen application rate was 240 kg/hm2.The SPAD value,plant height,dry matter quality of each organ at the ear pumping stage and maturity stage,the dynamic change of water nitrogen and phosphorus concentration in paddy field,rainfall at each growth stage,irrigation amount,nitrogen uptake in mature rice,stem tillers,grain yield and its constituent factors were determined under different treatment combinations,and the input-output ratio and water nitrogen use efficiency were converted.The main findings are as follows:1)Compared with conventional irrigation treatment,the SPAD value,crop growth rate,stem tiller ear rate,dry matter accumulation and distribution ratio of rice leaves from jointing to filling stage under dry and wet alternating irrigation treatment increased compared with conventional irrigation treatment.Compared with N1 treatment,the ear rate,crop growth rate,dry matter accumulation,number of grains per panicle and 1,000grain mass,setting rate and grain yield of N2 and N3 treated stems were increased,and the increase of grain yield of N2 treatment was higher than that of N3 treatment.Overall,compared with other treatments,AWDN2 treatment obtained higher SPAD value,stem tiller ear rate,crop growth rate,dry matter accumulation,harvest index,ear number,thousand grain quality,setting rate and grain yield.2)After the application of conventional fast-acting urea,the concentrations of total nitrogen（TN）and ammonium nitrogen（NH4+-N）in paddy surface water reached a peak concentration of 94.1 mg·L-1、60.02mg·L-1（2021）and 96.4 mg·L-1、60.26mg·L-1（2022）on the first day after fertilization,nitrate nitrogen（NO3+-N）reached a peak concentration of 1.70 mg·L-1（2021）、1.73mg·L-1（2022）,while after administration of controlled-release urea,both TN and NH4+-N reached peak concentrations of 17.7 mg·L-1、8.75mg·L-1（2021）and 16.9 mg·L-1、8.73 mg·L-1（2022）.Nitrogen application significantly increased the concentration of water nitrogen on the field surface.It was indicated that the 5 days of fertilization was a high-risk period for nitrogen loss in paddy fields.Compared with conventional irrigation treatment,the nitrogen concentration of field surface water under wet and dry alternating irrigation treatment increased by 1.3%（2021）and 1.4%（2022）.Compared with N1 treatment,the nitrogen concentration of field water under N2 and N3 treatment was reduced by 47.2%～85.2%（2021）and 48.2%～85.1%（2022）.The results showed that compared with conventional irrigation treatment and conventional fast-acting urea,alternating dry-wet irrigation and controlled-release urea could significantly reduce the nitrogen concentration of paddy water surface.3)The dynamic trend of total phosphorus（TP）and soluble phosphorus（DP）was roughly consistent,and both reached a peak concentration of 0.25 mg·L-1、0.05mg·L-1（2021）and 0.32 mg·L-1、0.07mg·L-1（2022）on the first day after fertilization,followed by a downward trend（except for fluctuations in concentrations affected by rainfall）.Compared with conventional irrigation treatment,wet and dry alternating irrigation treatment significantly reduced the concentrations of TP and DP in field water by 6.2%,5.6%（2021）,5.9%and 4.8%（2022）.Compared with N1 treatment,the concentrations of TP and DP in field water under N2 and N3 treatment decreased by 18.73%,13.75%,7.34%and 9.96%（2021）,17.32%,14.46%,18.35%and 10.22%（2022）.The results showed that the administration of controlled-release urea was beneficial to reduce the concentration of water and phosphorus in paddy fields.Compared with conventional irrigation farmers’habitual nitrogen application,AWDN2 can significantly reduce the concentration of water and phosphorus in paddy fields.4)Compared with conventional irrigation,wet and dry irrigation reduced the input of irrigation water,improved irrigation water utilization rate（IWUE）and water utilization rate（WUE）,and increased by 77.6%～83.5%and 39.8%～42.9%respectively in 2021.In2022,it increased by 43.6%～60.2%and 32.6%～34.1%,respectively.Compared with the fractional application of conventional fast-acting urea,the nitrogen fertilizer management measures of controlled release urea+topdressing of conventional fast-acting urea saved the labor input required for topdressing by 100 yuan and 200 yuan,respectively,and also improved the nitrogen fertilizer utilization rate by 6.8%～11.8%（2021）and 6.0%～11.2%（2022）,realizing the increase of rice yield and income.Considering the yield,water and nitrogen use efficiency and input-output ratio,the combination of 60%controlled-release urea+40%conventional fast-acting urea in dry and wet alternating irrigation is the optimal water and nitrogen management mode. |
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