Study On Optimized Water And Nitrogen Model Based On The Diagnosis Of Chlorophyll Nitrogen In Soil-Crop System

The Inner Mongolia Hetao irrigation district faced with serious problems what the polidy of Yellow River water,the excessive use of nitrogen fertilizer and the non-point source pollution.The study on the optimization of water and nitrogen in the irrigated area is an important scientific and technological requirement to improve the level of agricultural clean production and promote modern agriculture,it is also an important measure to maintain the agricultural environment in irrigation.In this study,the feedback mechanism of soil-crop system to water and nitrogen interaction was revealed by field experiment.The nitrogen nutrition diagnosis of maize was made from the point of view of chlorophyll CCI value,and the suitable water and nitrogen ratio was put forward.In order to save irrigation water resources,nitrogen fertilizer dosage,improve the farmland environment to provide useful reference indicators.The main conclusions are as follows:(1)The main physiological morphological indexes(plant height,stem diameter,leaf area,leaf chlorophyll content and root system)and soil environmental factors(soil water and salt,soil organic matter,nitrate nitrogen and nitrogen mineralization rate)increases with the increase of irrigation volume,but the difference of 90mm and 120mm was not significant.The physiological and morphological indexes of maize and the soil environmental factors were obviously increased at 135?225kg/hm2,and peaked at 225kg/hm2.When the amount of nitrogen applied was 280kg/hm2,the above indexes showed a decreasing trend.(2)Irrigation amount of 90mm than 60mm and 120mm of corn production increased by 17.93%and 3.28%.The amount of nitrogen applied was 225kg/hm2 compared to 135 kg/hm2 and 180 kg/hm2 of corn production increased by 11.77%and 8.02%,the amount of nitrogen applied was 280kg/hm2 than 225kg/hm2 of corn production increased by reduced 2.58%.The water use efficiency increased with the increase of nitrogen application rate,and decreased with the increase of irrigation amount.There was a positive correlation between nitrogen use efficiency and irrigation amount and nitrogen application rate.When the irrigation amount was 90mm and the nitrogen application rate was 225kg/hm2,the maize yield and nitrogen use efficiency peaked.(3)In this study,the critical nitrogen concentration dilution cure model of single maize was established in Hetao irrigation district(Nc?35.94W-0.34),this model can be used to diagnose the nutritional status of maize nitrogen,the results were as follows:when the irrigation amount was 90mm,the optimum amount of nitrogen applied was about 225 kg/hm2,the nitrogen nutrient index and chlorophyll CCI were significant,maize relative yield and chlorophyll CCI were extremely significant.Based on the diagnosis of critical nitrogen concentration dilution curve model,the optimum nitrogen application rate was 217kg/hm2 by the linear and platform model.Therefore,the optimized water and nitrogen model of maize was irrigation with 90mm and nitrogen application rate of 217kg/hm2.