Study On Variable Nitrogen Fertilization Decision Making System Of Wheat Based On WCSODS

During 2003-2005,Based on field experiments of wheat nitrogen fertilizer used and estimate and analysis for the wheat growth model-WCSODS,Variable Nitrogen Fertilization System of Wheat was constructed and validated. Simultaneously,the photosynthetic thetic product model was revised with nitrogen factor and validated systemicly under N stress condition. The results were as follows:Firstly, Based on enviorment of Zhengzhou city ,under N optimum Condition, There was high precision for phenophase and yield between the simulated and observed data with WCSODS. Compared with the observed, the error was 1-2 days for whole stage,3-6 days for elongation stage and 0-4 days for holding stage. The results also showed that the observed data accorded with the simulated data of the leaf area index tiller number and dry matter weight, the correlation coefficient between them were 0.9393 - 0.9949,the error of yield between simulated and observed was 2.8-30.9 kg/667m~2.But there are large error under N Stress Condition.Secondly,Following theory of nutrient balance and the principle of "crop-soil-enviorment-technology",Variable Nitrogen Fertilization System of Wheat was conceived,including N P K fertilization total amount before sowing and N amount after sowing,which combined according to spatial variability of soil nutrition wheat N requirement and LAI of different phonological prase,by causing the growth status coefficient to revive N amount before sowing,and determined optimum rate of N of wheat different phonological prase.The method of fertilizing N reduced waste of N and pollution of environment,at the same time reasonable method of fertilizing N was provide for wheat yield.Thirdly,By developing the effect models of N fertilizer application and nitrogen from soil on photosynthesis ,the photosynthetic thetic product model of WCSODS was improved and perfected.The results were follows: The improved model could simulate wheat growth and yield formation under N stress rationally. Under deficient or sufficient N application, the correlation coefficient between leaf area is 0.9614- 0.9816 0.9764-0.9866 between the dry matter above is 0.9223-0.9799 0.9108-0.9789,and between the yield is 0.8164,from the whole,LAI and the dry matter above's trend were coherent with N optimum Condition,which showed photosynthesis model's modification was reasonable and parameter was exact. The new model will be most suitable to forecast wheat yield and make a decision for wheat production in Henan province.Fourthly, Under the guild of Variable Nitrogen Fertilization System of Wheat, Field experiments of wheat nitrogen fertilizer used were carried out at Henan Agricultural University Research Station and Agricultural Research Institute of Hebi during 2004-2005.The results showed:There was significant for yields between the simulated and observed data and the correlation coefficient was 0.7799 and 0.7169.Compare with fertilize N amount under the guild of Variable Nitrogen Fertilization System and routine N amount,the results showed that under equal yields,43.5kg N was saved every 1 hm~2.This system not only save cost,but also gained significant benefit of protect environment and reduced soli pollution.