Effect Of Different Nitrogen Fertilizer Rate And Different Ratio Of Base And Topdressing On Nitrogen Utilization, Yield And Quality In Winter Wheat

The field experimentation was carried out at Qianzhuliu village, Beima town of Longkou in shandong provice from Octomber 2002 to June 2003.The experimentation was studied by using two different winter wheat cultivars, jiami20, which has 9000kg/hm2 yield potential and approximately 14% protein content, and yannong15, which has 8500kg/hm2 yield potential and approximately 15% protein content. Field culture method and 15N microplot method were used to study the effect of different nitrogen rate and different ratio of base and topdressing on nitrogen utilization, kernel yield and quality of jimai20. The main results as follows:1 The effect of different nitrogen rate and different ratio of base and topdressing on nitrogen utilization At the normal fertilizer rate (240kg/hm2 pure nitrogen), The treatment of 1/3 nitrogen used before sowing and 2/3 nitrogen used at jointing had the highest nitrogen use efficiency (NUE). The treatment that all nitrogen was used at jointing had the lowest NUE. Compared with the conventional treatment (240kg/hm2 pure nitrogen, 1/2 nitrogen was used before sowing and 1/2 nitrogen was used at jointing), the treatments of decreasing 30% nitrogen rate (168kg/hm2), increased the NUE significantly, but there was no significant difference each other.Above 70% of the accumulated nitrogen of wheat was derived from the soil, and below 30% was from fertilizer. This indicated that the accumulation of nitrogen was dependent on soil nitrogen mostly. At the fertilizer rate of 240kg/hm2, the treatment of nitrogen was all used at jointing had the highest percentage of soil nitrogen to total accumulated nitrogen of wheat, and the treatment of 1/3 nitrogen used before sowing and 2/3 nitrogen used at jointing had the lowest ratio. Compared with conventional treatment, the treatments decreasing 30% nitrogen rate, increased the percentage of soil nitrogen to total accumulated nitrogen of wheat significantly, and the treatment of all nitrogen used at jointing had the highest percentage. This indicated that both all nitrogen used at jointing and decreasing 30% nitrogen all stimulated the absorbing of soil nitrogen, the ratio of soil nitrogen to total accumulated nitrogen increasing.2 Effect of different nitrogen rate and different ratio of base and topdressing on soil nitrogen2.1 Effect of different nitrogen rate and different ratio of base and topdressing on soil nitrogenCompared with ck, nitrogen application improved the soil total nitrogen in 0~60cm soil layer at different growth stage. Compared with conventional treatment, the treatments, which all nitrogen was used at jointing, significantly improved the soil total nitrogen in 0~20 and 20~40cm soil layer from flagging to maturity, and the higher nitrogen content could supply enough nitrogen to wheat. About the total nitrogen content in 40~60cm soil layer, each nitrogen treatment had no significant difference.2.2 The effect of different nitrogen rate and different ratio of base and topdressing on alkali hydrolysable nitrogen contentThe treatments that nitrogen applied had the highest content than other stages in 0~20cm soil layer at flagging. The content of the two treatments that all nitrogen used at jointing was higher than other treatments, and the higher content could supply enough nitrogen to wheat. In 20~40cm soil layer, ck and the treatments that nitrogen used before sowing had the highest content at getting-up. At maturity, the content between the two treatments that all nitrogen used at jointing and the conventional treatment had no significant difference. In 40~60cm soil layer, at getting-up, ck and the treatments that nitrogen used before sowing had the highest total soil nitrogen than other growth stages. The content of the two treatments that all nitrogen used at jointing increased instantly. At maturity, the two treatments had the higher content and ck had the lowest content.2.3 The effect of different nitrogen rate and different ratio of base and topdressing on NO3--N content in soil Compared with ck, nitrog...