Effects Of Controlled Release N-Fertilizer On Plant Tissue And Soil N Concentration And Yield Of Cotton

In order to optimize the structure of N-fertilizers and improve the N-fertilizer use efficiency in furrow and border irrigations in cotton field and to provide the basis for controlled release N-fertilizer in applying to cotton producing, we spent 2 years'time consecutively in field trail to research the effects of CRNF and normal N-fertilizer with the application amount of 0,126,180 kg·hm^-2 respectively on plant dry matter accumulation, N uptake, content of soil nitrate nitrogen and the yield, as well as the effects of different blend ratio between the two fertilizers on cotton yield. The results show that under the treatment of low(126 kg·hm^-2) N & high N (180 kg·hm^-2), the dry matter accumulation increased in"S"type, it is proportional to nitrogen application rate, comparing with the treatment of urea which with the same content of N, the dry matter accumulation of CRNF is improved by 12.77% and 17.96% averagely. The experiment in the year of 2008 shows that the N absorption and absorption rate of CRNF are less than NNF in seeding and bud stages, but in the following stages, the results are just the opposite. In the experiment of 2009, the N accumulation of the treatment of CRNF is continuously more than NNF. The experiments also show that the treatment of low N and high N of the CRNF increased the apparent utilization rate by 12.59% & 10.56%, and the absorption of phosphorus increased by 7.78% & 19.42% at different levels, the uptake of K is much more than N's and P's. When N rate is less than 180 kg·hm^-2, the content of soil nitrate nitrogen is higher in seeding stage(soil depth: 0～90cm), but the content is lower in bud and bolling stages, and in florescence it has a tendency of increase, positive correlation is observed between the content of soil nitrogen and N-fertilizer. In 2008, the treatment of CRNF to the content of soil nitrogen in every stage is relatively stable; in 2009, the controlled release N-fertilizer treatment is higher than urea which with the same content of N. As far as the yield is concerned, ginned cotton is higher under the treatment of low N by 14.76%, and the N-fertilizer on the agronomic use efficiency of increased by 1.80kg·kg-1, high N treatment increased by 21.47% and 1.70 kg·kg-1 respectively. Comparing with the treatment of single CRNF, bulk blending 30% NNF improved cotton yield by 10.34%, but with the decrease of CRNF, the yield and quality are all has the tendency of decrease. We concluded that CRNF can stimulate the dry matter's accumulation and the absorption and utilization of N & P, it is good for the stability and increase of soil nitrate nitrogen, improved the cotton yield.