Emergy theory and method are used to evaluate the contribution of irrigation water, and the process of its utilization, in three agricultural systems. The agricultural systems evaluated in this study were rice, wheat,...Emergy theory and method are used to evaluate the contribution of irrigation water, and the process of its utilization, in three agricultural systems. The agricultural systems evaluated in this study were rice, wheat, and oilseed rape productions in an irrigation pumping district of China. A corresponding framework for emergy evaluation and sensitivity analysis methods was proposed. Two new indices, the fraction of irrigation water （FIW）, and the irrigation intensity of agriculture （IIA）, were developed to depict the contribution of irrigation water. The calculated FIW indicated that irrigation water used for the rice production system （34.7%） contributed more than irrigation water used for wheat （5.3%） and oilseed rape （11.2%） production systems in a typical dry year. The wheat production with an IIA of 19.0 had the highest net benefit from irrigation compared to the rice （2.9） and oilseed rape （8.9） productions. The transformities of the systems＇ products represented different energy efficiencies for rice （2.50E ＋ 05 sej .J^-1）, wheat （1.66E ＋ 05 sej .J^-1） and oilseed rape （2.14E ＋ 05 sej .J^-1） production systems. According to several emergy indices, of the three systems evaluated, the rice system had the greatest level of sustainability. However, all of them were less sustainable than the ecological agricultural systems. A sensitivity analysis showed that the emergy inputs of irrigation water and nitrogenous fertilizer were the highest sensitivity factors influencing the emergy ratios. Best Management Practices, and other agroecological strategies, could be implemented to make further improvements in the sustainability of the three systems.展开更多
The emergy concept was used to evaluate a pumping irrigation water production system in China. A framework for emergy evaluation of the significance of irrigation water and its production process was developed. The re...The emergy concept was used to evaluate a pumping irrigation water production system in China. A framework for emergy evaluation of the significance of irrigation water and its production process was developed. The results show that the irrigation water saved has the highest emergy value （8.73E ＋ 05 sej. J-1）, followed by the irrigation water supplied to farmlands （1.72E ＋ 05 sej.J-1）, the pumped water （4.81E＋04sej.-1）, with the lowest value shown from water taken from the local river （3.72E ＋04sej.j1）. The major contributions to the emergy needed for production are the inputs of soil and water. This production system could contribute to the irrigated agriculture and economy, according to several calculated emergy indices： emergy yield ratio （EYR）, emergy investment ratio （EIR）, environmental load ratio （ELR）, and environmental sustainability index （ESI）. The com- parative analysis shows that the emergy theory and method, different from the conventional monetary-based analysis, could be used to evaluate irrigation water and its production process in terms of the biophysical account. Additional emergy evaluations should be completed on different types of water production and irrigated agricul- tural systems to provide adequate guidelines for the sustainability of irrigation development.展开更多
文摘Emergy theory and method are used to evaluate the contribution of irrigation water, and the process of its utilization, in three agricultural systems. The agricultural systems evaluated in this study were rice, wheat, and oilseed rape productions in an irrigation pumping district of China. A corresponding framework for emergy evaluation and sensitivity analysis methods was proposed. Two new indices, the fraction of irrigation water （FIW）, and the irrigation intensity of agriculture （IIA）, were developed to depict the contribution of irrigation water. The calculated FIW indicated that irrigation water used for the rice production system （34.7%） contributed more than irrigation water used for wheat （5.3%） and oilseed rape （11.2%） production systems in a typical dry year. The wheat production with an IIA of 19.0 had the highest net benefit from irrigation compared to the rice （2.9） and oilseed rape （8.9） productions. The transformities of the systems＇ products represented different energy efficiencies for rice （2.50E ＋ 05 sej .J^-1）, wheat （1.66E ＋ 05 sej .J^-1） and oilseed rape （2.14E ＋ 05 sej .J^-1） production systems. According to several emergy indices, of the three systems evaluated, the rice system had the greatest level of sustainability. However, all of them were less sustainable than the ecological agricultural systems. A sensitivity analysis showed that the emergy inputs of irrigation water and nitrogenous fertilizer were the highest sensitivity factors influencing the emergy ratios. Best Management Practices, and other agroecological strategies, could be implemented to make further improvements in the sustainability of the three systems.
文摘The emergy concept was used to evaluate a pumping irrigation water production system in China. A framework for emergy evaluation of the significance of irrigation water and its production process was developed. The results show that the irrigation water saved has the highest emergy value （8.73E ＋ 05 sej. J-1）, followed by the irrigation water supplied to farmlands （1.72E ＋ 05 sej.J-1）, the pumped water （4.81E＋04sej.-1）, with the lowest value shown from water taken from the local river （3.72E ＋04sej.j1）. The major contributions to the emergy needed for production are the inputs of soil and water. This production system could contribute to the irrigated agriculture and economy, according to several calculated emergy indices： emergy yield ratio （EYR）, emergy investment ratio （EIR）, environmental load ratio （ELR）, and environmental sustainability index （ESI）. The com- parative analysis shows that the emergy theory and method, different from the conventional monetary-based analysis, could be used to evaluate irrigation water and its production process in terms of the biophysical account. Additional emergy evaluations should be completed on different types of water production and irrigated agricul- tural systems to provide adequate guidelines for the sustainability of irrigation development.
