Leaching Loss And Movement Of Nitrate In The Soil Of Wheat-Corn Double Cropping System And Nitrogen And Irrigation Recommendation

The purpose of this study was to quantify the movement and distribution of nitrate in the soil profile and nitrogen uptake by crop in winter wheat-corn double system in Hebei plain through different fertilizer and irrigation treatments. Firstly we studied temporal dynamics of nitrate concentration in the soil solution with different nitrogen fertilizer rates and irrigation treatments in different growing period. The soil samples were obtained by drills which can take soil from deep profiles, then the nitrate leaching loss through a soil layer was calculated by quality approach, in order to point out the main factors which can affecting nitrogen leaching loss and the main periods in which lots of nitrate loss during wheat growth, Secondly we analyze the constitutes of output and uptake by crop and yield which was caused by different fertilizer and irrigation treatments. Finally bring forward economical quantity of fertilizer and irrigation. The following conclusion were drawn from the experimental and simulated studies:1. The change of ammoniacal nitrogen contents in the same soil layer is small in different growth periods, then increased in short time after corn harvest, but the diversity is not remarkable in different growth period or different fertilizer treatments in the same soil layer.2. The content of nitrate in soil increased with fertilizer application increasing, whereas the content decrease with the irrigation increasing. The losses of leaching increased when nitrogen fertilizer and irrigation increased. In wheat-corn double system, the tiptop nitrate leaching through 180cm soil depth were 2, 9, 19kg/hm² in one year with N150, 250, 350 kg/hm²treatments.During wheat season the irrigation before planting and the first irrigation in the next year caused lots of nitrate leached.3. The NO₃^-N accumulation peak transfer from 120cm to 140cm after wheat-corn double system in Luquan. On condition of N3,the content of NO₃^--N higher than other treatments significantly below 140cm in arenaceous soil in Hengshui. The effect of soil texture on nitrogen leaching is apparent in the case.4. Fertilization and irrigation effect yield by working on constitutes which make up of yield, such as spike number, seed of every spike, weight of one thousand seeds and content of...