Studies On The Application Technique Of Controlled-release Urea In Clear Production Of High-quality Winter Wheat

This experiments was carried out at Zhongcun village, Longkou city of Shandong provice from Octomber 2003 to June 2004. The effects of combining conventional urea with controlled-release urea on grain yield, grain quality, nitrogen fertilizer utilization efficiency of winter wheat and accumulation of NO3--N in soil was investigated with field plot experiment .The main results were as follows: 1 Effects of controlled-release urea on grain yield and grain quality of winter wheat 1.1 Effects of controlled-release urea on grain yield 1.1.1 Effects of controlled-release urea on wheat population and dry matter accumulation and partationing of dry matter Tiller number, accumulation of dry matter and partitioning into grains was increased with nitrogen fertilizer application. Significant higher percentage of ear-bear tiller and partitioning of dry matter into grains and more dry matter accumulation were also observed with the combination applications of conventional urea with controlled-release usea, comparing with applying conventional urea only, among which the effect of combination applications of conventional urea with controlled-release urea for basal application was best. 1.1.2 Effects of controlled-release urea on grain yield and yield components of wheat Nitrogen fertilizer increased spike number of unit area and 1000 grain weight, and increased grain yield correspondingly. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea increased spike number of unit erea, which led to striking increase in grain yield. 1.2 Effects of controlled-release urea on grain quality of wheat 1.2.1 Effects of controlled-release urea on grain protein content and gluten content Nitrogen fertilizer increased markedly grain protein content and wet gluten content and SDS sedimentation volume. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea improved markedly grain protein content and SDS sedimentation volume with the same amount of nitrogen applied, or remained unchanged with 30% decline in the amount of nitrogen applied. 1.2.2 Effects of controlled-release urea on grain protein quality Applying nitrogen fertilizer increased obviously water absorption, dough development time and dough stability time of flour, and reached 5% or 1% significant level. However, the effects of combination application of conventional urea with controlled-release urea on grain protein quality was not significant, comparing with applying conventional urea only. 1.2.3 Effects of controlled-release urea on grain protein composition Nitrogen fertilizer applied increased markedly the content of monomeric protein, soluble glutenin and insoluble glutenin in grain. The combination applications of conventional urea with controlled-release urea increased mainly monomeric protein content, comparing with applying conventional urea only.2 Effects of controlled-release urea on the uptake and distribution of nitrogen in wheat plant 2.1 Effects of controlled-release urea on nitrogen metabolism in wheat plant Nitrogen fertilizer improved the activities of NR, EP and CP in flag leaf and GS in kernel, which was involved in nitrogen assimilation and protein degradation in flag leaf. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea increased markedly the activities of NR and EP in flag leaf and the activities of GS in kernel, but kept the activities of CP in flag leaf unchanged with the same amount of nitrogen applied; and decreased obviously the the activities of NR and CP in flag leaf, but kept the activities of EP in flag leaf and GS in kernel unchanged with the amount of nitrogen applied decrease by 30%. Nitrogen fertilizer also increased soluble protein content in flag leaf and in kernel. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea increased markedly those parameters mentioned above with the same amount of nitrogen applied, among which the effect of combination applications of conventional urea with controlled-release urea for basal application was best. 2.2 Effects of controlled-release urea on the accumulation and distribution of nitrogen in wheat plant Applying nitrogen fertilizer promoted the uptake and accumulation of nitrogen in wheat plant and in kernel. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea increased those parameters mentioned above significantly at 1% level with the same amount of nitrogen applied, or kept them unchanged with the amount of nitrogen applied decrease by 30%. 2.3 Changes in the nitrogen fertilizer utilization efficiency and dependent rate on the soil nitrogen of wheat Comparing with applying conventional urea only, the combinationapplications of conventional urea with controlled-release urea increased obviousely nitrogen fertilizer utilization efficiency and decreased the dependent rate on soil nitrogen of wheat. 3 Effects of controlled-release urea on the accumulation of nitrogen in soil 3.1 Effects of controlled-release urea on the accumulation of NO3--N in soil With applied nitrogen fertilizer, the accumulation amount of NO3--N in soil was increased correspondingly. Comparing with applying conventional urea only, the combination applications of conventional urea with controlled-release urea increased the accumulation amount of NO3--N in top layer (0-40cm) soil and decreased its accumulation amount in deeper layer (40-160cm) soil. In general, the conbination conventional urea with controlled-release urea reduced the amount of NO3--N drenching from top to deeper soil, and lessened the pollution of NO3--N on underground water. Comparing with the combination applications of conventional urea with controlled-release urea for basal application, the combination applications of conventional urea with controlled-release urea for top-dressing increased markedly the accumulation amount of NO3--N in 0-200cm soil layer at maturation with the same amount of nitrogen applied. From preplanting to the maturation, the accumulation amount of NO3--N showed the tendency of rising first and then declining, once more rising in 0-100cm soil layer. The accumulation amount of NO3--N was lowest at preplanting and was highest at the maturation in the treatments of applying conventional urea only and combination application of conventional urea with controlled-release urea for basal application (240kgN/hm2). However, in the other treatments, the accumulation amount of NO3--N was highest before winter and was lowest at jointing. The accumulation amount of NO3--N firstly descended and then rose, once more descended in 100-200cm soil layer. The accumulation amount of NO3--N was highest before sowing and was lowest at the maturation except the treatment of no nitrogen.3.2 Effects of controlled-release urea on the accumulation of NH4+-N in soil From preplanting to the maturation, the accumulation amount of NH4+-N in 0-100cm soil layer was more than that in 100-200cm soil layer. In 0-100cm soil layer and 100-200cm soil layer, the accumulation amount of NH4+-N firstly descended and then rose, once more descended. In 0-100cm soil layer, the accumulation amount of NH4+-N of the majority treatments was highest at jointing and was lowest at maturation. In 100-200cm soil layer, the accumulation amount of NH4+-N was highest bofore sowing and was lowest at maturation. 3.3 Effects of controlled-release urea on the accumulation of Nmin in soil Applying nitrogen fertilizer increased the accumulation amount of Nmin. When the same amount of nitrogen applied, the combination applications of conventional urea with controlled-release urea increased the accumulation amount of Nmin in 0-200cm soil layer at mature period, comparing with applying conventional urea only; the combination applications of conventional urea with controlled-release urea for top-dressing also increased the accumulation amount of Nmin in 0-200cm soil layer at mature period, comparing with the combination applications of conventional urea with controlled-release urea for basal application. From preplanting to the mature period, there was tendency that the accumulation amount of Nmin rose firstly and then descended, once more rose in each treatment (excapt the treatment of no nitrogen) in 0-100cm soil layer, it was highest before winter and was lowest at anthesis. However, there was tendency that the accumulation amount of Nmin descended firstly and then rose, once more descended in 100-200cm soil layer. The accumulation amount of Nmin was highest before sowing and was lowest at mature peroid (excapt the treatment of applying conventional urea only).