| Modern intensive kiwifruit farming modes worldwide are generating increasing environmental stress and hindering the sustainable development of the industry.At the same time,global warming,resource depletion and food security have led to increasing concerns about agricultural carbon emissions(CEs)in various countries.Therefore,this study proposes a combined approach,composed of emergy analysis,economic analysis and carbon accounting,to comprehensively evaluate performance of kiwifruit cropping systems.The proposed approach not only considers the environmental sustainability,but also assesses the corresponding GHG emission intensity and economic performance as well as the comprehensive performance,which can reveal the key factors affecting performance of the system from diverse angles.China,Italy and Iran,as the main countries for kiwifruit production in the world,were selected as case studies,and the plantation area was based on 1 ha.Main results of the study are summarized as follows:(1)The results of emergy flow analysis show that the total emergy input of Shaanxi Kiwifruit planting system(SXPS)is 4.01E+16 sej/yr,in which the local renewable input(R1),local non-renewable input(N),purchased renewable input(FR)and purchased nonrenewable input(FN)account for 1.40%,2.02%,7.31%and 89.27%respectively.The total emergy input of Sichuan Kiwifruit planting system(SCPS)is 2.62E+16 sej/yr,in which Ri,N,FR and FN account for 2.92%,5.99%,3.90%and 87.19%respectively.The total emergy input of Italian kiwifruit planting system(ITPS)is 1.99E+16 sej/yr,in which R1,N,FR and FN account for 3.25%,3.68%,5.75%and 87.33%respectively.For the Iranian kiwifruit planting system(IRPS),the total emergy input is 1.27E+16 sej/yr,in which R1,N,FR and FN account for 6.03%,1.60%,6.11%and 86.27%respectively.In general,FN accounts for the highest proportion in total emergy input of each system.(2)The quantified results of pollutant emissions’ impacts show that SXPS has the highest emissions’ impact(7.14E+15 sej/yr),in which ecological services(R2)and emergy loss(F2)accounts for 98.12%and 1.88%,respectively.The total emissions’ impact of ITPS is 3.13E+15 sej/yr,to which R2 and F2 contributes 98.11%and 1.89%,respectively;the total emissions’impact of SCPS is 1.85E+15 sej/yr,in which R2 and F2 shares 98.10%and 1.90%,respectively;IRPS has the lowest emissions’impact(5.75E+14 sej/yr),in which R2 and F2 accounts for 93.91%and 6.09%,respectively.The pollution emissions’ impact of the four systems is mainly from R2,most of which is used to dilute the total phosphorus in the wastewater.Therefore,the key to reduce the ecological service is to improve the efficiency of P fertilizer utilization.(3)From the emergy-based indicators:for the UEV indicator,IRPS has the highest resource efficiency(2.09E+11sej/kg),followed by SCPS(4.32E+11sej/kg)and SXPS(7.49E+11sej/kg),while the ITPS has the lowest resource efficiency(8.10E+11sej/kg);for the%R,IRPS performs the best with 12.14%,followed by ITPS(9.00%)and SXPS(8.71%),while SCPS has the worst resource structure(6.82%);the results of the EYR indicator reflects that SCPS has the highest economic efficiency or competitiveness(1.10),followed by IRPS(1.08)and ITPS(1.07),while SXPS has the lowest economic efficiency or competitiveness(1.04);for the ELR indicator,it follows the trends of SCPS(13.66)>SXPS(10.48)>ITPS(10.11)>IRPS(7.24).Therefore,SCPS has the highest environmental load and IRPS has the lowest environmental load;in terms of ESI index,IRPS has the highest level of sustainability(0.15),followed by ITPS(0.11)and SXPS(0.10),and SCPS ranks the last(0.08).Generally,IRPS has the highest environmental sustainability level in the four systems.(4)In terms of carbon emission intensity:SXPS ranks the top one(0.16 kg CO2-eq/kg),followed by ITPS(0.15 kg CO2-eq/kg)and SCPS(0.12 kg CO2-eq/kg),IRPS ranks the last(0.10 kg CO2-eq/kg).For SXPS,the carbon emissions are mainly from fertilizers(58.90%),followed by labor(29.19%),electricity(5.42%),etc.For SCPS,labor produces the most carbon emissions(56.59%),followed by fertilizers(26.29%),electricity(9.31%),and gasoline combustion(4.93%).In ITPS,fertilizers(38.56%)and pesticides(33.12%)are the two main contributors to carbon emissions,followed by labor(15.88%)and electricity(10.32%).IRPS has the lowest carbon emissions,mainly from labor(42.20%),followed by fertilizers(31.86%),diesel combustion(13.06%)and electricity(11.28%).This reflects that in kiwifruit farming systems,carbon emissions mainly come from fertilizer use,followed by labor.(5)According to the results of economic analysis,the unit economic cost of SCPS is the highest with 2.63 CNY/kg,followed by Shaanxi(2.41 CNY/kg)and Iran(1.24 CNY/kg),and Italy has the lowest unit economic cost(0.70 CNY/kg).For the ratio of output to investment,the performance of the four systems follows the trends of IRPS>ITPS>SXPS>SCPS.Therefore,the economic benefit of IRPS is the best,while that of the two systems in China is relatively worse.(6)According to the co-benefit index(CBI),the CBI value of IRPS,ITPS,SCPS and SXPS is 16.60,0.77,0.68,and 0.22 respectively.And this shows that,IRPS system has the best comprehensive performance.For CBI of SXPS,PEI(-0.49)has the largest adverse impact,followed by EOIRK(-0.44),CEI(-0.17)and ESI(-0.09),orderly.Among SCPS,PEI(0.57)contributes the most to CBI,followed by CEI(0.14).ESI and EOIRK have a negative effect on index value;therein,EOIRK has the larger negative effect than ESI.For ITPS,the largest negative impact comes from PEI(-0.18),followed by CEI(-0.13)and ESI(-0.02)in order.For IRPS,PEI(4.16)contributes the most to CBI,followed by EOIRK(0.83)and ESI(0.38),while CEI(0.28)contributed the least.Finally,this study proposes the following recommendations to promote comprehensive performance of Chinese kiwifruit planting,including(1)promoting the use of straw and animal manure as fertilizers,(2)regulating the use of agricultural materials such as chemical fertilizers and pesticides,and(3)strengthening the innovation and application of agricultural equipment and technologies. |
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