Experimentation And Simulation On Carbon And Nitrogen Cycle

The influences of environmental and management factors on the growth and development of winter wheat and summer maize, the released CO₂ and N₂O and the nitrate leaching were studied in detail based on field experiments with different treatment of nitrogen apply and straw-return. Meanwhile, DAISY model was modified and validated according to the simulation of dynamic of crop yields of winter wheat and summer maize. The results summarized here as following:1. Straw return and nitrogen application are two important factors to effect the N₂O emission of soil. Most important of all, the N₂O emission of soil can be decreased by wheat - straw - return but it can be hasten by the application of manure. 1.61 percent nitrogen lost by the means of N₂O in manure application treatment while only 0.22 percent nitrogen lost by the treatment of N3Sl(600kgN/hm2.a and wheat-straw-return)2. NH/-N reached 10-24 mg/kg and NO3-N maintenance a high level in a short time of 600 Kg/hm2-a apply. Although, NO3-N influenced by irritation and rainfall in a large degree in treatment of 200 kgN/hm2 application. Compare to the treatment of 400 Kg/hm2a nitrogen application, the treatment of 600 Kg/hm2a nitrogen application can decrease the 23% nitrogen absorb by seed and 11.74% nitrogen by dry matter.3. The release of CO2 high to be 1.80 kg/m2 in the treatment of wheat and maize return. And manure application didn't influence the release of CO2.4. Daisy model, which integrated the crop model and water-nitrogen dynamic model, had consistent simulated results with the observed after being modified by field test and were suitable to be used in simulation of the growth and nitrogen uptake of whinter wheat and summer maize, carbon and nitrogen dynamic as well: NO3-N can be simulated by DAISY when nitrogen application under 400Kg/hm2-a. and the model can be well run to simulate and forecast the quantity of nitrogen absorbed by plant and the release of N2O by soil. But, when we forecast the release of CO2, we found that, DAISY can be well run to simulate when nitrogen application under 400Kg/hm2-a while the results will be higher than the fact when nitrogen application higher than 400Kg/hm2-a.Though the whole experience, nitrogen application must be control be lower 400400kg/hm2 a, and adopt wheat straw return to achieve economy and ecology benefit.