An integrated simulation model for a semi-arid agroecosystem in the Loess Plateau of northwestern China

We apply a resource integration approach to address increasing crop and forage production in a semi-arid agroecosystem in northwestern China. A holistic modeling approach was employed to study improvement in agricultural practices with respect to ecosystem conservation. Using a proposed rotational scheme for winter wheat and alfalfa production, portions of arable land are allocated for raising animal forage in order to improve soil productivity. Animal manures are returned to the soil to stabilize the structure further and to maintain fertility. Regional climate and topography are included in the simulation model. A series of 40-yr simulation runs for ravine tablelands and hilly topography were conducted to investigate model behavior. Long-term application of nitrogen fertilizer as an alternative management practice was evaluated using the model, but detrimental effects on primary and secondary production from such a practice were predicted by simulation results. The impact of population pressure on agricultural systems was also considered.