| According to the actuality, background and develop direction of agricultural production, the Huaian city was divided into three agricultural regions. The first region is the plain agricultural region of Huaibei in the north of Subei's irrigation channels. The second one is the low-lying plain region in the south of the channels. And the last one is the region of Huainan with some hills. A great area of fertile soil was formed by the long-term cultivation and utilization. Statistical data showed that the infield with the highest soil fertility is 30 percent of total infeild; the infield with medium soil fertility is 50 percent; and the one with the lowest soil fertility is 20 percent. However, with the improvement of tilth system and recultivation and the increased utilization of nitrogen fertilizer, some problems about fertilizer utilization were exposed in rice-wheat rotation system, they could be listed as follows. The quantity of used nitrogen fertilizer was increased and that of P2O5 K2O were on the low side, it lead to a low use efficiency of fertilizer. The ratio of organic fertilizer and inorganic fertilizer was in malajustment, and the variety of fertilizer was simplex. The distribution and utilization of fertilizer were unreasonable. Nowadays, in the rice-wheat rotation regions, the amount of used fertilizer (pure) in high-yield field was 990-1050 kg per ha, it was 46 to 51 percent higher than that in the ecumenic fields, the ratio of N, P2O5 and K2O was 1:0.27:0.36. The field experiments was carried out to study the effect of different amount of nitrogen fertilizer on the productivity of rice from 2002 to 2003 in the three regions, the studied rice cultivar was Wuyujing 3 which was used universal in local. The results obtained were as follows. Without any nitrogen fertilizer, the rice yield was 6750 kg/ha, 6000 kg/ha and 5250 kg/ha in Qunan region (with the highest soil fertility), Huainan region (with medium soil fertility) and Huaibei region (with the lowest soil fertility), respectively. Supplied 195-240 kg/ha, 240-285 kg/ha and 270-330 kg/ha nitrogen fertilizer, respectively, all of these three regions achieved the greatest productivity.Field experiments were carried out to study the different used quantity of N fertilizer and different ratio of N, P and K on the N absorption and transformation, N accumulation in seeds and the content of proteins. The results showed that supplied N, P2O5 and K2O as 1:0.27:0.36to rice plants, N accumulation in seeds and the content of proteins were obviously more than that in control, and the general economical benefit came into the greatest extent.The soil with low fertility in Huaian was filmy silt and sandy soil. Serious absence from P and K of the soil and unreasonable utilization of fertilization had turned into the main barrier in the production of rice and wheat. With the result of experiments, the utilization of fertilizer could be improved, then increase the utilization of organic fertilizer, P and K fertilizer to field, it could not only increase the yield of rice and wheat, but also increase the content of P and K in the soil.To study the utilization of N fertilizer on the photosynthetic rate and yield of wheat, contrastive experiments on two wheat cultivars were carried out in the three regions with treatments of different using time and quantity of fertilizer from 2003 to 2004. The results obtained was as follows. Supplying fertilizer in elongation period could increase the photosynthetic rate in anthesis. The photosynthetic rate of Yannong 19 and Huaimai 20 were in the high extent when supplied with moderate fertilizer in elongation period. Supplied fertilizer to Yannong 19 in elongation period could increase the amount of spike obviously. The weight of seeds has no significant difference when treated with different quantity and using time of fertilizer. Supplied fertilizer to Huainai 20 in elongation period could increase the amount of spike and the weight of seeds obviously. Utilization of moderate fertilizer could increase the amount of spike and got a h...
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