Applicability Of DSSAT Model To Cotton Growth At Different Nitrogen Levels In Hebei

With the development of computer technology,the use of information science to study the problem of agricultural production has become a new direction of agricultural technology research.Computer model has become a powerful tool in agricultural research.This study uses the DSSAT model of IBSNAT(International Benchmark Sites Network for Agrotechnology Transfer)-the standard base point network project of international agricultural technology transfer.And simulate cotton planting in Hebei area.With the field experiment combined with DSSAT model,the effect of different fertilization measures on cotton yield was simulated with the advantage of model precision and quantitative,and a new technique was provided to improve the nitrogen use efficiency of cotton cultivation in Hebei Province,reduce the amount of fertilizer application and reduce the cost of production.In this study,DSSAT model v4.7 version was used to test Cotton Variety"Lu Mian Yan 28".A total of four nitrogen treatments were set up:N0 nitrogen free,N1 low level nitrogen 120 kg/hm~2,N2 medium level nitrogen 240 kg/hm~2 and N3 high level nitrogen480 kg/hm~2.Phosphate fertilizer,potash fertilizer and other field management measures are in line with the local conventional high-yielding cotton fields.In the model simulation process,In the model simulation process,the parameters of the corresponding parameters were determined by the genetic parameters of the other cotton varieties in the DSSAT model,and then by simulating the field measured parameters of"Lu Mian Yan 28"recorded in 2012,the genetic parameters of the crop varieties in the model were combined with the built-in"GLUE"tool in the DSSAT model to carry out the genetic parameters of the crop varieties.The adjustment was made and verified by the results of the 2017 test.The results showed that.In the DSSAT model,the genetic parameters of cotton crop varieties calibrated can be used to simulate cotton seed cotton yield,aboveground dry weight and leaf area index.The NRMSE of cotton seed yield between yield return and simulation verification were 5.46%and 1.23%respectively.In the simulation of the change of the growth morphology of cotton,the NRMSE of day by day tops dry weight change:yield return were N0:8.63%,N1:9.48%,N2:8.50%,N3:14.16%,and simulation verification were N0:7.99%,N1:12.15%,N2:11.69%,N3:12.48%.The NRMSE of the day by day leaf area index change:yield return were N0:7.99%,N1:12.15%,N2:11.69%,N3:12.48%,and simulation verification were N0:11.67%,N1:3.45%,N2:2.12%,N3:3.76.This shows that the DSSAT model,which has been adjusted by variety parameters,has good applicability to the different nitrogen application levels of"Lu Mian Yan 28"in different years in Hebei area.It can be used to evaluate the yield simulation of different nitrogen application and help the relevant practitioners to optimize the management of cotton production.The NRMSE values of dry weight of day by day for each treatment are more than 20%.This study makes a preliminary attempt to apply the CROPGRO-Cotton sub model in the DSSAT model.The study proved that 1),the DSSAT model adjusted by variety parameters can be used to evaluate the cotton economic yield,the tops dry weight and the leaf area index of different nitrogen application.2)the simulation of tops dry weight allocation in the aerial part of the DSSAT model is poor,and the relevant parameters in the model need to be adjusted for improvement.3)DSSAT models cannot respond to the high nitrogen input production well.Because the inaccuracy of the tops dry weight allocation parameters.4)The DSSAT lack the field management measures,such as cotton pruning,in cotton cultivation measures simulation.And it do not estimate the effects of these measures on the growth of cotton and the distribution of dry weight.The experiment proved that the DSSAT model can be used to simulate the yield changes of cotton with different nitrogen application levels.In actual production,it can help the relevant practitioners to fertilize cotton scientifically and improve the utilization rate of nitrogen fertilizer.