Study On Optimal Irrigation Scheme Of Winter Wheat In North China Based On DSSAT Model

The North China Plain, is one of the main origin of winter wheat with its adequate solar radiation resources, seasonally fluctuating temperature and fertile deep soil. This wheat origin belong to the monsoon climate, serious shortage of rainfall and precipitation concentration in summer, which for the winter wheat growing season before October a year until early June of the following year and consumption of water is serious water shortage, so the winter wheat growth relies heavily on irrigation. Hebei area of water resources is a serious shortage, so the development of local area winter wheat optimal irrigation scheme has important significance.In this paper, we introduce DSSAT model, to test of Chinese Academy of Sciences at Luancheng agro ecosystem station as a representative sample, using the totally years of meteorological and field observations and data management, research works in North China the best irrigation scheme. Mainly have the following contents:(1)Firstly, use the two varieties (41851 and Kenong 199) to adjust the DSSAT model parameters, and to fit the simulation analysis, the results showed that the DSSAT model in the region have better effect.(2)Using established the DSSAT model parameter system. Based on the existing research results and local management practices and establishment of irrigation time respectively in winter (12/01), jointing(3/29) and heading (4/20) and filling (5/15) in the period, and combined with 0-4 times of five irrigation level, a total of 16 kinds of combination irrigation, winter wheat growth period and yield simulation, finally established yield and water use efficiency of the best combination is suitable for local optimum irrigation scheme.(3)Using Pearson Ⅲ distribution method according to totally years (a total of 15 years of precipitation division dry year, wet year and normal year. And on the type to indicate the year, the 16 kinds of irrigation schemes yield and water using efficiency of the comparative analysis, so as to obtain the optimal irrigation scheme under different precipitation years.The main conclusions of this paper are as follows:(1) On variety 41851,the normalized root mean square error of the yield return and simulation verification were 8.38% and 11.93%, respectively, based on the DSSAT model; The normalized root mean square error of the yield return and simulation verification of variety kenong 199 were 7.16% and 6.59%, respectively, based on the DSSAT model; During the development of simulation:the normalized root mean square error of varieties 41851 and Kenong 199 anthesis and maturity model to fitting and validation were less than 10%. The simulation results show that the model is better in the local area.(2) The simulation and analysis of 16 kinds of combination of irrigation results show that: in conventional tillage, irrigation methods and compared with the full nutrient supply conditions, irrigation frequency and time on winter wheat yield and water use efficiency of significant.The optimal yield irrigation scheme is this:irrigation three times (winter+jointing +heading water)> irrigation four times> irrigation two times (jointing+heading water)> irrigation one time (jointing water)> rain; The optimal scheme of water use efficiency is this: irrigation two times (jointing+heading water)> irrigation one time(jointing water)> irrigation three times (winter+jointing+heading water)> irrigation four times> rain. So when the irrigation time is three we can get the highest yield. The average yield of irrigation three times is 7006.87kg/hm2, compared with the average value of irrigation two times 6848.27kg/hm2 is high 158.6kg/hm2. The average water use efficiency (WUE) of irrigation three times mean is 14.38kg/hm "mm, this is much lower than that of the irrigation two times when the mean 16.955kg/hm2"mm. The optimal water use efficiency is when the irrigation times is two. Comprehensive yield and water use efficiency analysis, the yield and water use efficiency of two times of irrigation (jointing+heading water) were better, and the best irrigation scheme was obtained.(3) Selection of 1999-2000、2002-2003、2009-2010, respectively, as the representative of dry year, wet year and normal year, combination of different irrigation on Yield and water use efficiency of analysis. The results show that:in the wet year when irrigation one time (jointing stage water), the yield of 7317 kg/hm2, WUE of 17.96kg/hm2-mm, yield and WUE are the best; in the normal year when irrigation 2 times (jointing stage and heading water), the yield of 7820 kg/hm2, WUE of 18.28kg/hm2·mm, yield and WUE are the best; in the dry year when irrigation 3 times (wintering, jointing stage and heading water), the yield of 8034 kg/hm2, WUE of 18.72kg/hm2·mm, yield and WUE are the best.