Dynamic analysis of emergy for agro-ecosystem in the region of cropland to grassland conversion — A case study of Beizhuang Village‚Zhenyuan County in Gansu Province
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DOI:10.7606/j.issn.1000-7601.2008.01.21
Key Words: conversion of cropland to grassland  agro-ecosystem  emergy
Author NameAffiliation
HUANG Wen-de College of Agronomy?Gansu Agricultural University?Lanzhou, Gansu 730070, China 
NIU Jun-yi College of Agronomy?Gansu Agricultural University?Lanzhou, Gansu 730070, China 
GAO Yu-hong College of Agronomy?Gansu Agricultural University?Lanzhou, Gansu 730070, China 
YANG Xiao-zhou College of Agronomy?Gansu Agricultural University?Lanzhou, Gansu 730070, China 
ZHAO Kui College of Agronomy?Gansu Agricultural University?Lanzhou, Gansu 730070, China 
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Abstract:
      Taking Beizhuang village,Zhenyuan County of Gansu Province as an example and using H.T.Odum emergy analysis method,this paper studies the changes of agro-ecosystem emergy after cropland to grassland conversion.The results indicate that after cropland to grassland conversion, net emergy yield ratio increases by 35.14%,environmental loading ratio decreases by 8.31%,emergy sustainability index(ESI) increases by 47.38%,and emergy stability index increases from 0.809 to 1.015 in Beizhuang village agro-ecosystem.The cropland to grassland conversion plays an important role in the improvement of agro-ecosystem productivity and sustainable development.But the system coupling degree between agriculture and animal husbandry decreases by 41.74%,we should adopt measures to enhance it and realize the balance development of agro-ecosystem.