Abstract: Based on the concept of water environment carrying capacity and by using artificial neural network, the evaluation model of regional water environment carrying capacity was built from the viewpoint of thresholds, and applied to evaluate the water environment carrying capacity in Liaoning Province. The calculations with the model showed that from 2000 to 2004, the index of water environment carrying capacity in Liaoning Province was 0.29, 0.36, 0.32, 0.37 and 0.43, respectively, suggesting that the water environment carrying capacity in this province was ascending on the whole, but still weak. The model built in this paper had the specialties of simple structure and easily modeling, with which, the regional water environment carrying capacity could be reflected intuitionally.

Key words: Optimized N management, Soil nitrate-N content, Apparent N losses, Crude protein content