Abstract:After a joint research conducted in the University of Western Australia in 1985-1986, CHAGAN, a comprehensive mathematical model that simulate the dynamic behaviour of N-cycling of integrated farming and animal husbandry ecosystem of Cha-gan village in northeast China was developed and was used to predict 10-years trend of N-balance in three different land use Systems.The System was divided into 8 subsystems. 88 N-flows were traced which cover almost all possible flows within and among the 8 subsystems and ...