【作者】 孙毓临；

【导师】 曾清如；

【作者基本信息】 湖南农业大学 ， 生态学， 2010， 硕士

【摘要】 本文在实验室条件下,研究了硝化抑制剂与作物秸秆混施对红壤中氮素矿化及金属活性的影响,重点研究了温度、水分等环境因子对土壤氮素矿化及金属活性的影响,以及双氰胺与水稻秸秆混施对土壤氮素矿化及金属活性的动态影响。主要研究结果如下：在作物秸秆分解的前14d,硝化抑制剂对土壤pH值的提高不明显。此时土壤pH值提高的主要原因是秸秆所含有机氮矿化为铵态氮,消耗了氢根离子。随着秸秆分解的程度加深,土壤中铵态氮的含量增加,土壤硝化势增强。在没有施用硝化抑制剂的情况下,铵态氮很快转化为硝态氮,释放了氢根离子,从而导致土壤pH值的下降；在施用了硝化抑制剂的情况下,铵态氮主要被微生物固持成为微生物氮,这部分氮具有较高的活性和循环速率,当土壤中交换态铵量降低时,其又会不断矿化成无机态氮,并释放到可提取的铵态氮库中。因此硝化抑制剂的促进了铵态氮的生物固持,使土壤中可提取的铵态氮库保持在较高水平。在作物秸秆分解的中间阶段,硝化抑制剂抑制表现为较强的硝化抑制效果,在本研究中表现为：未添加DCD的处理组其土壤pH值在第10d即开始迅速下降,而添加了DCD的处理组其土壤pH值在第20d才开始出现缓慢下降。同时,单因子实验及正交实验表明：土样含水量能显著影响秸秆分解时氮素矿化过程,随含水量的变化,土壤pH值、铵态氮含量、硝态氮含量、活性金属铝、锌、锰、铁含量均出现显著性差异(F<0.05)。在作物秸秆分解的后期阶段,从第30d开始硝化抑制剂的作用减弱,表现为土壤pH值下降、铵态氮含量降低、硝态氮含量增加、土壤金属活性增加。更多还原

【Abstract】 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.更多还原