高矿化度水灌溉林地土壤质量演变规律及定量评价

The evolution and quantitative evaluation of soil quality was the main content of the contemporary soil science, and irrigated with highly mineralized water was view as a study core for the effect of soil quality on Tarim Desert Highway shelter-belt. Therefore, this project plan to start with the main process of soil quality changes, through researches on soil physical, chemical and biological processes, clarify the response mechanisms that apparent characteristics of soil properties on soil quality under high-salinity water irrigation. Select indicators that characterized the soil quality, use integrated, multiple indexes method, establish a soil quality indicators which was suitable for the soil under long-term high salinity water irrigation in extreme arid region, also quantitative estimation soil quality of the Tarim Desert Highway shelter-belt. It's not only avail to reveal the soil physical-chemical-biological associated processes under high-salinity water irrigation in extremely arid region, but also has an important supplement and perfect effect to the development of soil science, was also an important study of man-land relationship in extremely arid desert, as well as provides scientific theories for the sustainable management of the Tarim Desert Highway .

土壤质量的演变规律与定量评价是现代土壤学研究的主要内容，而高矿化度水灌溉则是影响塔里木沙漠公路防护林土壤质量的核心问题之一。因此，本项目拟以土壤质量变化的主要过程入手，通过对土壤物理、化学、生物学过程的研究，阐明在高矿化度水灌溉下土壤特性表观特征对土壤质量的响应机制；遴选表征土壤质量指标，运用综合、多指标量化手段，建立适宜于极端干旱区长期高矿化度水灌溉下土壤质量指标体系，定量评价长期高矿化度水灌溉下塔里木沙漠公路防护林土壤质量。这不仅有利于揭示极端干旱区高矿化度水灌溉下土壤物理-化学-生物等关联过程，而且对土壤科学的发展具有重要的补充与完善，也是极端干旱风沙地区人地关系的重要研究内容，同时也可为塔里木沙漠公路的可持续管护提供科学理论依据。

对高矿化度水滴灌下沙漠人工林土壤质量特征及评价的研究，不但对了解高矿化度水滴灌下人工林土壤物理、化学、生物学等关联过程有重要理论意义，而且对高矿化度水滴灌下人工林对风沙土土壤质量改良，以及极端干旱区人工林可持续发展，极端干旱风沙地区人地关系等研究都具有十分重要的参考价值。本文以塔里木沙漠长期高矿化度水滴灌下的人工林土壤为研究对象，研究了长期高矿化度水滴灌下不同树种人工林土壤质量随林龄和灌溉水矿化度变化的基本特征，构建了人工林土壤质量评价指标体系，建立了土壤质量综合评价模型，并对人工林土壤质量进行了综合评价。主要结论如下：.⑴ 人工林建成后，土壤性质在表层变异性最强，最能代表流动风沙土向半固定和固定风沙土演变过程中土壤性质的变化。.⑵ 林龄对不同树种人工林表层土壤质量指标的影响规律相同。随林龄增大，土壤明显细化， pH增大，电导率增大，除全钾外，其他养分含量增加，土壤脲酶和过氧化氢酶活性增强，微生物量碳氮含量显著性增大。.⑶ 灌溉水矿化度对人工林土壤质量指标影响规律不同。随灌溉水矿化度的增加， pH变化不显著；电导率增大；柽柳和沙拐枣林土壤养分含量均增加，梭梭林土壤速效钾和阳离子交换量增加，其余养分指标先增加后减少；微生物量碳和氮的含量显著性减小。当滴灌水矿化度为2.88~12.07g/L时，脲酶和过氧化氢酶活性均随灌溉水矿化度的增加而增强，当滴灌水矿化度为12.07~29.70g/L时，梭梭人工林土壤脲酶和过氧化氢酶活性随滴灌水矿化度的增大而减弱。.⑷ 对19项土壤质量指标进行分析，筛选出了8项土壤质量评价指标，构建了高矿化度水滴灌下人工林土壤质量综合评价指标体系和评价模型。.⑸三种树种人工林土壤质量等级随林龄的增大而增加，且梭梭和沙拐枣较柽柳更有利于风沙土土壤质量的改良。不同矿化度水灌溉对人工林土壤质量指数的影响表现为：当灌溉水矿化度≤23.80g/L时，人工林土壤质量指数受其影响不显著，当灌溉水矿化度＞23.80g/L时，梭梭人工林土壤质量指数显著下降。