Water-emergy-carbon Impact Assessment And Sustainable Development Optimization Of Protected Vegetables

Facility agriculture is one of the representative models in the process of agricultural modernization and has become a key agricultural type in the world.As the main part of facility agriculture in China,protected vegetable plays an important role in agricultural production and national economy,but its production process also causes considerable resource consumption and environmental pollution.In particular,it has brought obstacles to China’s agricultural water saving and carbon reduction work and sustainable green production.To evaluate the impact of water,energy and carbon on resources and environment and the sustainability of the protected vegetable production system(PVPS)in China,and to provide effective policy suggestions for the optimization,the comprehensive methods of water footprint,carbon footprint and emergy analysis were applied to systematically study the PVPS in China.The results show that:(1)The total water footprint consumption of PVPS in China in 2018 was 6.1 billion m~3,and the water consumption level of PVPS in each province can be roughly divided into four echelons,among which north China and The Yangtze River Basin consumed more water.The blue water footprint gradually decreases from east to west and from south to north.The grey water footprint was denser in Henan,Shandong,Hebei,Sichuan and Jiangsu,accounting for 76%of the total.The classification of water footprint density was mainly affected by the grey water footprint density and all provinces can be divided into three areas:low,middle and high density,and the high density areas were all concentrated in North China.The provinces with high water footprint intensity mainly concentrated in the Yellow River Basin,especially in Henan,Shandong,Shaanxi and Ningxia.The stress index of blue water footprint and grey water footprint showed the same trend and obvious spatial difference.Henan,Shandong,Shaanxi,Sichuan and Hubei showed high blue water footprint stress index and grey water footprint stress index simultaneously.(2)The energy consumption of PVPS in China in 2018 was 3.85E+10 MJ.The energy consumption of fuel power,fertilizer and drainage and irrigation was higher in Henan;the energy consumption of pesticides,agricultural film and farm manure was higher in Shandong;the energy consumption of agricultural machinery working was higher in Jiangsu and Sichuan;the energy consumption of pumping was higher in Shaanxi,and the energy consumption of drainage and irrigation was higher in Hebei,Shanxi and Shaanxi.The total carbon emission of PVPS in China was 10.58 million t CE,and the net carbon footprint was 7.41 million t CE.Compound fertilizer,transportation and nitrogen fertilizer contributed a large proportion,and the net carbon footprint of each province showed obvious polarization.The carbon eco-efficiency of PVPS was0.299,which was relatively low,especially in North China and northwest China.In the analysis of high carbon emissions in different production links,agricultural resources input in Zhejiang,Shaanxi,Jilin and Henan were high,and agricultural working efficiency in Jilin,Shaanxi,Zhejiang and Shanghai was low.(3)The total emergy input of PVPS in China in 2018 was about 3.04E+22 sej,which mainly depended on the purchase emergy that cannot be updated,especially labor,land rent and fertilizer.The total emergy input showed a decreasing trend from south to north and from east to west.The emergy input per unit area showed opposite results.The emergy input structure of different regions resulted in significant regional heterogeneity of emergy indicators.The EYR in south China was relatively high,and the ability to use local resources was obviously better than that in north China.The ELR in central China was significantly higher than the national average.Beijing(0.165),Qinghai(0.141),Shandong(0.130)had higher ESI,and Central China and the upper and middle reaches of the Yangtze River were poor in ESI.(4)Integrating various emergy input structure improvements,such as reducing local groundwater input,reducing non-renewable energy input,increasing mechanization level and reducing labor input,the sustainability of the national PVPS will increase by 28.63%by 2030compared with 2018.Based on the comprehensive perspective of water-carbon-emergy,it is crucial to reduce the input of water and energy resources,reduce greenhouse gas emissions,and prioritize the regulation of provinces with high resource pressure and low ecological efficiency and sustainability.Among them,development and utilization of green water,facilities improvement and irrigation upgrading,perfect planting strategy,reducing the use of chemical fertilizers,pesticides,agricultural film,promoting clean energy,improving mechanization rate and growers’ability and other measures to improve the utilization rate of agricultural resources input and agricultural working efficiency are effective means.In the future,it will be the best way to improve the resource and environmental sustainability of PVPS combined with the overall adjustment of national investment structure and the in-depth optimization of local areas.This study will provide data reference and theoretical support for promoting the low-carbon development of agricultural and rural modernization under the goal of"carbon peak and carbon neutralization",and forming a modern facility agricultural production structure that matches market demand and resource and environmental carrying capacity.