Analysis of Electricity Cost of Agricultural Irrigation and Drainage in Experiment Station

The electricity cost of agricultural irrigation and drainage in the Dahe Ex- periment Station was analyzed. The results showed that from 2012 to 2016, the annual total power and total electricity cost increased year by year. The higher the electricity consumption was, the lower the factor adjusted power price was. The an- nual factor adjusted power price decreased from 532.5 yuan （above the national standard） to -599.78 yuan （below the national standard）. The electricity consumption was always highest in June. The more the rainfall from June to September was, the less the monthly electricity usage was. The collect electricity charge to total electricity charge ratio was 1.26%-1.34%, the directory electricity charge to total electricity charge ratio was 96.34%-99.80%, and the electricity loss of transformer was 288-496 kW/h.

Field experiments on greenhouse gas emissions and nitrogen and phosphorus losses from rice paddy with efficient irrigation and drainage management

Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-environmental impacts of efficient irrigation and drainage on rice paddy.The results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding irrigation.Seasonal comprehensive global warming potentials(GWP) of methane and nitrous oxide were 62.23 gCO2 m-2 for rice paddy under the controlled irrigation,reduced by 68.0% compared with flooding irrigation.Due to large reduction in seepage and surface drainages,nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%,nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and drainage.Nitrogen loss through ammonia volatilization was reduced by 14.0%.Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission,nitrogen and phosphorus losses and their pollution on groundwater and surface water.

Mechanism of water savings and pollution reduction in paddy fields of three typical areas in southern China

Field irrigation and drainage regulation and fertilization application could affect water utilization and pollution transportation in a paddy field.In this study,representative rice-producing areas of Zhejiang Province in southern China were selected to study the effects of different field water level control(conventional irrigation and drainage W0,controlled irrigation and drainage W1 and W2)and different fertilization methods(2 times of fertilization F2 and three times of fertilization F3)on water irrigation quantity and consumption of rice,rice growth,water utilization,and pollution reduction.Results showed that field water level control had a great effect on irrigation quota in growing period rather than that in soaking period,and irrigation quota for W0 was 37.0%-71.7%higher than that for W1 and W2 in the whole growth period of rice.Although the upper limit of rain storage was greatly increased by W1 and W2,on the contrary,the yield under W1 and W2 was 0.4%-2.1%higher than that under W0.Water consumption,water leakage,and evapotranspiration were 16.63%-34.4%,39.97%-60.8%,and 9.40%-31.53%lower under W1 and W2 than those under W0,respectively,while it showed no significant changes under W1 and W2.Rainfall use rate and WUEI(water use efficiency of irrigation)under W1 and W2 had been significantly improved by 8.20%-129.58%and 31.58%-201.61%compared to W0.The contribution of nitrogen and phosphorus loss from surface water accounted for 90%and the total pollution load of total nitrogen(TN),NO_(3)^(-)-N,NH_(4)^(+)-N and chemical oxygen demand(COD)were 20.0%-63.4%,21.8%-66.3%,21.5%-63.8%,and 21.4%-46.5%lower for W1 and W2 than that for W0,respectively.Meanwhile,compared to F2,dispersed fertilization(F3)was beneficial to increase the yield and decrease pollutant load.Additionally,the path of IRA→NH_(4)^(+)-N→COD and IRA→WCA→WUE_(I) presented partial remediation effect,and the effect size was 23.6%and 38.1%,respectively,the path of IRA→WUE_(I)→WUE_(ET) presented a full remediation effect,and the path of IRA→WCA→WUE_(ET) presented suppression effect.

Optimizing water-saving irrigation schemes for rice(Oryza sativa L.)using DSSAT-CERES-Rice model

Rice is one of the major crops in China,and enhancing the rice yield and water use efficiency is critical to ensuring food security in China.Determining how to optimize a scientific and efficient irrigation and drainage scheme by combining existing technology is currently a hot topic.Crop growth models can be used to assess actual or proposed water management regimes intended to increase water use efficiency and mitigate water shortages.In this study,a CERES-Rice model was calibrated and validated using a two-year field experiment.Four irrigation and drainage treatments were designed for the experiment:alternate wetting and drying(AWD),controlled drainage(CD),controlled irrigation and drainage for a low water level(CID1),and controlled irrigation and drainage for a high water level(CID2).According to the indicators normalized root mean square error(NRMSE)and index of agreement(d),the calibrated CERES-Rice model accurately predicted grain yield(NRMSE=6.67%,d=0.77),,shoot biomass(NRMSE=3.37%,d=0.77),actual evapotranspiration(ETa)(NRMSE=3.83%,d=0.74),irrigation volume(NRMSE=15.56%,d=0.94),and leaf area index(NRMSE=9.69%,d=0.98)over 2 a.The calibrated model was subsequently used to evaluate rice production in response to the four treatments(AWD,CD,CID1,and CID2)under 60 meteorological scenarios which were divided into wet years(22 a),normal years(16 a),and dry years(22 a).Results showed that the yield of AWD was the largest among four treatments in different hydrological years.Relative to that of AWD,the yield of CD,CID1,and CID2 were respectively reduced by 5.7%,2.6%,8.7%in wet years,9.2%,2.3%,8.6% in normal years,and 9.2%,3.8%,3.9% in dry years.However,rainwater use efficiency and irrigation water use efficiency were the greatest for CID2 in different hydrological years.The entropy-weighting TOPSIS model was used to optimize the four water-saving irrigation schemes in terms of water-saving,labor-saving and high-yield,based on the simulation results of the CERES-Rice model in the past 60 a.These results showed that CID1 and AWD were optimal in the wet years,CID1 and CID2 were optimal in the normal and dry years.These results may provide a strong scientific basis for the optimization of water-saving irrigation technology for rice.