Evaluation of ecological and economic benefits of crop production in Jiangsu Province

Economic benefits,energy output and soil NPK output/input for current crop production in Jiangsu Province were studied. Results show that cotton in combination with corn, wheat or rape can yield high economic benefits in the regions with intensive labor, small-scale production. Rotating rice and corn, wheat or rape can not only save labor, but also yield high economic and energy benefits in the region with low labor,large-scale production. For five crop types, N input is larger than N output, P input and output is basically in balance and K input is lower than output. In reference to ecological and economic benefits and soil fertility equilibrium maintenance, N fertilizer input should be reduced to 165～225kg/hm² for rice,75～105 kg/hm² for wheat,90～165kg/hm² for corn, 120kg /hm² for cotton and 60～90kg/hm² for rape;and K fertilizer input should be increased to 120kg/hm² for cotton. For the other crops,soil K may be supplemented by plowing crop straw/stalk back to field.