【作者】 谭向平；

【导师】 和文祥；

【作者基本信息】 西北农林科技大学 ， 微生物学， 2010， 硕士

【摘要】 土壤酶是土壤重要组分之一,在营养物质转化、能量转移、污染物清除等过程中发挥着重要作用,同时其与土壤质量的关系也是人们关注的主要课题之一。本文采用非缓冲液法,对黄土高原沟壑代表区域——长武县土壤酶(转化酶、纤维素酶、淀粉酶、脲酶、蛋白酶、磷酸酶、芳基硫酸酯酶、过氧化氢酶、脱氢酶、尿酸盐酶)特征及微生物区系进行了较为系统的研究,并借助动力学手段研究了土壤酶酶促反应的机理及与土壤性质间的关系。以期筛选获得可较敏感反映土壤肥力水平的酶类,构建土壤酶学监测指标,完善土壤酶学理论等,最终从土壤酶角度,为该地土壤质量评价提供依据;为当地农业的可持续发展奠定基础。本论文研究获得的主要结果如下:(1)黄土高原沟壑区农田土壤十种土壤生化活性中仅脲酶、转化酶、磷酸酶、脱氢酶及呼吸强度与大多数化学性质达显著或极显著相关水平,且其变异系数较大,揭示此五种生化活性关系密切,对土壤环境条件改变更敏感。可在一定程度上可指示土壤肥力水平的高低。(2)黄土高原沟壑区果园表层土壤的转化酶、脲酶、磷酸酶、脱氢酶活性比下层分别大1.2、1.5、1.6、1.3倍,表层土壤有机质含量是下层的1.2倍,反映出这四种酶与果园土壤有机质变化是一致的;不同果园中酶空间变化的情况是不同的,随土层加深,磷酸酶、脲酶活性显著下降的比例分别为96%、88%,而转化酶和脱氢酶活性的较差,只达到60%、52%,过氧化氢酶活性变化趋势不明显;相关分析结果表明土壤酶与土壤化学性质关系十分密切,揭示出土壤脱氢酶、磷酸酶、转化酶、脲酶可作为本地区果园土壤的肥力指标。主成分分析构建的土壤酶—化学性质综合信息系统不仅可以反映出土壤酶与土壤化学性质对土壤肥力的贡献及其相互关系,而且综合得分能够直接反映出土壤肥力水平的高低,可作为土壤质量评价的指标之一。(3)黄土高原沟壑区高肥力土壤中水解酶Km高于低肥力,但差别不大,均为同一数量级。不同肥力间的脲酶Vmax、Vmax/Km、k值达到显著性差异。转化酶Vmax/Km、k能够反映土壤酸碱度的变化,脲酶动力参数与化学性质达到显著相关,表明脲酶的动力学参数Vmax、Vmax/Km、K可作为该地区土壤肥力评价的指标之一。(4)利用稀释平板法研究土壤微生物区系的变化,发现细菌占土壤微生物总数83.35%～93.47%、真菌小于0.02%、放线菌占6.51%～23.07%。反映该地农田土壤微生物多样性的Shannon-Wiener指数、Simpson指数、Mcintosh指数范围分别在0.24～0.56、0.12～0.36、0.80～0.94之间。相关分析表明多样性指数较好地反映了该地土壤肥力的水平,可作为土壤质量监测的生物学指标之一。(5)计算获得了我们构建的土壤总体酶活性指标(TEI),其与其他土壤生物学指标BIF、EAN一起与土壤化学性质相关分析结果表明,除EAN外,二者关系均达到极显著正相关,尤以TEI、TEI5最佳;主成分分析得到的土壤肥力综合得分与三个参数BIF、TEI和TEI5均达极显著正相关,揭示出土壤酶参数TEI可作为土壤肥力水平指标之一。表明相对单个酶活性参数来讲,总体酶活性指标更具准确、适应性更广泛。(6)黄土高原沟壑区宅基地通过一年的复垦后,有机肥+菌肥和有机肥处理增强了土壤转化酶、脲酶、磷酸酶、芳基硫酸酯酶、脱氢酶活性、呼吸强度和放线菌数量,施用化肥、复合肥对土壤酶和微生物数量影响不大。过氧化氢酶对不同施肥制度反应不敏感。总体酶活性指标(TEI)可以很好的评价不同施肥措施对土壤生物学性质的影响,并从各方面获得有机肥能够增强宅基地土壤生化活性和肥力水平,是一个很好的改良措施。综上所述,非缓冲液法更能准确反映土壤酶的真实状况;总体酶活性指标TEI可作为本地区土壤肥力评价及预警的指标。但要利用此指标来对该地区农田土壤肥力质量进行分级,还得作进一步的研究。更多还原

【Abstract】 Soil enzyme is one of the major components in soil, playing important roles in transfer of nutrient and matter, shift of energy and remediation of pollutants. And meanwhile the relationship between soil enzyme and soil quality is a main scientific project to study. So, this experiment investigates the soil enzymes activities (such as invertase, cellulose, amylase, protease, urease, phosphatase, arylslphatase, dehydrogenase, catalase, uricase) by using no-buffer method and microbiota in Changwu where is as the representative of Loess Plateau gully region; studies the reaction mechanism of hydrolytic enzymatic activity, and also the relationship between it and soil properties by kinetic. It is expected to find some soil enzymes which can sensitively reflect the level of soil fertility, built soil enzymatic monitoring indicators and developed soil enzyme theory; and finally, provided the basis for soil quality assessment and laid the foundation for the sustaining development of agriculture in Loess Plateau from soil enzyme perspective. They will be showed as following:(1) In Loess Plateau gully region, biochemical activities of soil urease, invertase, dehydrogenase and respiration of farmland were more sensitive to environmental change among these ten biochemical activities. There was a significant correlation between urease, invertase, phosphatase, dehydrogenase and respiration, and also between these five soil biochemical activities and most of soil chemical properties. This indicated that these five soil biochemical activities can be used as indicators for soil fertility.(2)Invertase, urease, phosphatase, and dehydrogenase activities in surface soil were respectively 1.2, 1.5, 1.6, 1.3 times higher than that in subsoil in Loess Plateau gully region. And soil organic matter content in surface soil is 1.2 times higher than that in subsoil. It indicated that the four soil enzymes had the same regularity with soil organic matter. Soil enzyme spatial variation was different in different orchards. As the soil depth increased, phosphatase and urease activity significantly had proportion of 96% and 88% decreases, while invertase and dehydrogenase activities only had proportion of 60% and 52% decreases. There was no significant influence on hydrogen peroxide activity. The correlation coefficient showed that soil enzymes and soil chemical properties related significantly. This indicated that soil dehydrogenase, phosphatase, invertase, urease can be used as indicators of orchard soil fertility in this region. Construction of principal component analysis of soil enzymes - the chemical nature of the integrated information system can not only reflect soil enzymes and chemical properties had effects on soil fertility and their relationships, but also the comprehensive scores directly reflected soil fertility, it can be indicator to evaluate soil quality.(3)In Loess Plateau gully region, Km of hydrolase changed in the same rank quantitatively, but high fertility soil’s was higher than low fertility.Vmax, Vmax/Km and k of urease were significant differences among different fertilizers. Vmax/Km and k of invertase could reflect the change of pH. There were significant positive correlation between urease kinetics and soil chemical characteristic, it was revealed that the Vmax、Vmax/Km and k of urease could be one of indexes to evaluate fertilizer of soil.(4)Pour plate method was used to study the soil microflora. The results showed bacteria, fungi and actinomyces accounted for 83.35%～93.47%, less than 0.02% and 6.51%～23.07% of the total of soil microorganism, respectively, indicating that the Shannon-Wiener index、Simpson index and Mcintosh index of this area were 0.24～0.56、0.12～0.36、0.80～0.94 respectively. the correlation analysis showed the diversity index could correctly describe the soil fertility of this area, and could be used as one of the biological indicators for the soil biological survey.(5)Among combinational parameters such as BIF, EAN, TEI and TEI5 obtained in this experiment, BIF, TEI and TEI5 had a significantly positive correlation with chemical properties with TEI5 as the most significant. This suggested that these three parameters can be used to monitor soil fertility. By processing the data of soil biochemical activities and chemical properties in principal component analysis and clustering analysis, the soil information system obtained in this experiment can better show the variation of soil fertility and the multiple scores were significantly positive correlated with BIF, TEIand TEI5, and this indicated that they can be used to monitor soil fertility levels. A simplified expression of the total enzymatic activity index may be more useful than individual soil enzyme activity to measures of soil quality.(6)Addition of the organic manure and bacterial manure on homestead caused significant increases in the activity of some enzymes (such as invertase, urease, phosphatase, arylslphatase, dehydrogenase) and the respiration rate and the number of actinomycete tested. The increases were much higher than a year of reclamation ago. But addition of fertilizer or compound fertilizer had little effect on soil enzymes and number of soil microorganisms. Catalase activity didn’t change in different fertilization system. Total enzymatic activity index (TEI) can be a good evaluation of different fertilization on soil biological properties, and organic fertilizer is a appropriate soil improvement measures that can enhance soil biological activity and fertility in homestead.To sum up, our results confirm that enzyme activity can be determined more accurately by no-buffer method than by buffer method, and the total enzymatic activity index (TEI) is suitable indicator of soil fertility and monitoring soil status in Loess Plateau gully region. But to use this index to soil fertility in the region to grade, have to be studied further.更多还原