Abstract: Nutrient balance of fixed monitoring sites in new farmland by different ways of fertilization in raperice and wheatrice alternating rotation system and its effect on crop yield in North Zhejiang Plain was studied for 7 season crops in 4 years. The results showed that the apparent surplus of nutrients in spring crops, and the actual balance of nitrogen, phosphorus profit rate were above 100%, while phosphorus and potassium deficient in rice season. Application of organic fertilizer and straw stalk return to the field could be integrated to maintain the supplydemand balance of NPK nutrients and increase crop yields. The crop yield in spring season was positively correlated with the total NPK nutrient actual balance profit and loss rate, but late rice could get the best yield by the actual balance of the total NPK rate of 5%. In the condition of certain chemical N input, rice yield was also positively correlated with the phosphorus and potassium actual balance profit and loss rate.

Key words: new farmland, fertilization, paddy riceupland crop rotation, nutrient balance, crop field