Impact Of Climate Change On Maize Yield And Water Footprint Of Production In Weibei Highland

Maize is the largest crop with its yield and planting area in China at present,which plays an important role in ensuring food security and the healthy sustainable development of social and economic.Global climate change characterized by climate warming is a consensus among scholars from various circles.Compared with irrigated agriculture,rain-fed agriculture is vulnerable to climate change.The impact of climate change on crop yield and water use efficiency is a hot research topic at present.But there is little research on rain-fed agriculture,and the statistical regression analysis method is usually used,which can not reveal the response of rain-fed crop growth and development to climate change,it is difficult to form a support for the strategy formulation of rain-fed agriculture to cope with climate change and agricultural production layout planning,it is difficult to form a support for the strategy formulation of dryland agriculture to deal with climate change and agricultural production layout planning.Based on the accounting method of water footprint of crop production in field scale,using CERES-Maize model to evaluate the impact of climate change on yield and water use efficiency of rain-fed maize.Study selected China first crop——maize as the research object,Weibei highland in the central part of Shaanxi Province was the typical dryland farming area in the north of China,which was set as the study area,experiment data at maize field was used to evaluate CERES-Maize model's applicability,Lastly,we used the meteorological data produced from regional climate model(RegCM4.0)to analyze the trend of maize yield and water use efficiency under the RCP2.6 and RCP8.5 climate scenarios.The main progress is as follows:(1)CERES-Maize model can well simulate the yield and phenology datas of rain-fed maize,the model had good applicability in the rain-fed agricultural area in Weibei highland.The mean absolute relative error(ARE)and average normalized root mean square error(NRMSE)between the simulated values and the observed values of phenology datas and yield were between 1.17%and 8.27%,the mean values of consistency index(d)and the determination coefficient(R~2)of the simulated and measured values were 0.94 and 0.80respectively.At the same time,the simulation of cumulative evapotranspiration in the whole growth period of maize was also more accurate.(2)Climate change showed a warm and dry trend from 1961 to 2016,the temperature and precipitation will increase significantly from 2017 to 2050.In the past 56 years(1961~2016),the temperature of the two stations in the study area showed a significant upward trend,solar radiation,precipitation,wind speed and relative humidity all showed a downward trend,the trend of drought was obvious.Under the RCP2.6 and RCP8.5 climate scenarios,the temperature of the two stations will increase significantly from 2017 to 2050,Solar radiation and wind speed show a fluctuating upward trend,precipitation and relative humidity show a slightly downward trend.Compared with the historical period,precipitation will increase significantly,the increasing range of the two climate scenarios is very close,which is 9.59%and 9.24%respectively.(3)The excessive temperature rise had an obvious negative impact on maize yield,and the amount of fertilizer was negatively correlated with the water footprint of maize production.Under the RCP2.6 climate scenario,maize yield showed an increasing trend with increasing temperature and effective precipitation during the growing season;Under the RCP8.5 scenario,maize yield showed a declining trend with increasing temperature and decreasing effective precipitation during the growth period.Under the RCP2.6 climate scenario,The interannual variation of maize evapotranspiration could be divided into two periods:fast rising period(2017~2027)and fluctuating decreasing period(2027~2050);Under RCP8.5 climate scenario,there were two stages of slight increase(2017~2039)and rapid rise(2039~2050).The yield and evapotranspiration of maize under RCP8.5 scenario were higher than those under RCP2.6 scenario.the water footprint of maize production under two climate scenarios was approximately same,the average value is 0.38 m~3/kg,both of them showed a decreasing trend before 2050.(4)Meteorological factors,agricultural investment and management level had a significant impact on the water footprint of maize production;Improving rainwater utilization and fertilizer productivity is the key to reduce water footprint of rainfed maize production in rain-fed areas.Precipitation and fertilization had the greatest impact on maize yield,the excessive temperature rise had an obvious negative effect on maize yield.Sensitivity analysis shows that the evapotranspiration of maize was the most sensitive to relative humidity(-1.11),followed by daily maximum temperature,sunshine hours,wind speed,and daily minimum temperature(0.01).Contribution analysis results show that the contribution rate of daily maximum temperature(4.51%)to maize evapotranspiration was the largest,followed by relative humidity,wind speed,daily minimum temperature,and sunshine hours(0.35%).In order to effectively deal with the negative impact of climate change on the rain-fed crop yields,we should further improve the efficiency of resource utilization,develop circular agriculture,reduce greenhouse gas emissions,and prevent the temperature from rising too fast.we should adopt measures such as conservation tillage,improving soil structure,enhancing soil water storage and preserving moisture capacity,adopting the measures of farmland microcatchment and the suitable agronomic water-saving model,developing rainwater catchment irrigation,selecting and cultivating water-saving and drought-resistant varieties,and improving precipitation utilization ratio and utilization efficiency.In addition,we should do a good job of early warning and response to drought and other natural disasters,in order to reduce the impact of disasters on maize yield.