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Effect Of Crop Straws Applied With Nitrification Inhibitors On Nitrogen Mineralization And Metallic Activity In Red Soils

Posted on:2011-07-08Degree:MasterType:Thesis
Country:ChinaCandidate:Y L SunFull Text:PDF
GTID:2143360308963180Subject:Ecology
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In this paper, the effect of crop straws applied with nitrification inhibitors, dicyandiamide (DCD) and thiourea (TU), on the nitrogen mineralization and metallic activity in the red acid soil was studied respectively. The pivot was the impact of environmental factors, such as the temperature and moisture. Also, the long-term influence of rice straw applied with DCD on the nitrogen mineralization and metallic activity was studied under the simulated conditions. Now the main results are as follows:In the first 14 days of the degradation process of crop straws, the application of nitrification inhibitor didn't make a significance improvement to the pH value. The main reason for the improvement of pH value is the transformation of organic nitrogenous into NH4+-N. In this process, the H+ was consumed largely. As the decomposition of organic nitrogenous, the concentration of NH4+-N increased. So the tendency of nitrification increased synchronously. Without nitrification inhibitors, NH4+-N will change into NO3--N quickly. And this process will release H+ which can decrease the pH value. While with the application of nitrification inhibitors, NH4+-N will change into MBN. This kind of nitrogen can be circulated efficiently and will not cause the acidity.In the middle term of degradation process of crop straws, nitrification inhibitor took effect pronouncedly. In the groups without DCD, the pH value decreased rapidly in the 10d. While in the groups added DCD, the pH value began to decline on the 20d quite slowly. At the same time, the single factor experiment and the orthogonal experiment indicated that the moisture was the most important factor which can influence the decomposition intensively. When the moisture changed, the pH value, concentration of NH4+-N, NO3--N, active-Al, active-Zn, active-Mn and active-Fe all changed significantly (F<0.5).In the later stage of the degradation process of crop straws, the effect of nitrification inhibitor weakened in the case of degradation or adsorption. Then, in the later 30 days, the pH value declined, the concentration of NH4+-N dropped, and the concentration of NO3--N and active metals increased.
Keywords/Search Tags:soil, crop straw, nitrification inhibitor, nitrogen, pH value, metallic activity
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