【作者】 张宏；

【导师】 刘建军；

【作者基本信息】 西北农林科技大学 ， 生态学， 2016， 硕士

【摘要】 本文对黄土丘陵沟壑区侵蚀劣地乔木林、灌木林、草地及农田4种土地利用方式土壤的物理性质、化学性质及土壤酶酶活性进行相应研究,在大量的野外调查及室内试验分析的基础上,通过对数据的整理统计,对该地区土壤的基本特征做出了全面的研究。研究结果如下:(1)不同土地利用方式对土壤容重的影响不同,乔木林与灌木林对土壤结构的改善优于草地和农田,土壤容重趋于减小;乔木林土壤容重最小,灌木林次之,农田最大。(2)4种土地利用方式下土壤含水率均随土层深度的增加而减小;乔木林土壤保水性能最好,各层及整体含水率最高,灌木林次之,农田最差。(3)该区土壤机械组成以粉粒为主,4种土地利用方式以及同一土地利用方式各层间粉粒含量差异不显著;4种土地利用方式土壤粘粒含量均随土层深度的增加而减小,就整个土壤剖面来说乔木林的粘粒含量最高,灌木林次之,农田最低;砂粒含量与粘粒则相反。(4)4种土地利用方式下土壤有机质、氮素及磷素均随土层深度的增加而降低,且在0~60cm各层间下降速率较快;土壤不同土地利用方式下土壤养分含量有所不同,乔木林的土壤有机质、氮素、磷素以及全钾含量均高于灌、草及农田,农田由于连年施用钾肥的缘故,表层速效钾含量在4种土地利用方式中最高;4种土地利用方式的综合肥力表现为乔木林>灌木林>草地>农田。(5)不同土地利用方式土壤表层酶活性差异显著,乔木林的4种酶活性均处于最高水平,灌木林次之,农田最低;土壤表层酶活性之间相关程度密切。(6)不同土地利用方式土壤理化性质各指标间存在密切的相关性,但土壤砂粒含量与其它指标间相关性差;该区土壤表层4种酶活性与土壤养分间有密切的相关关系,除速效钾与4种酶活性呈不同程度的负相关关系,其它各养分指标均与4种酶活性呈显著或极显著正相关。更多还原

【Abstract】 Through field investigations, laboratory analysis and statistical analysis, we comprehensively studied the soil physical properties, chemical properties and enzyme activity of high wood land, shrub land, grassland and farmland four land use types at eroded land in Loess Hilly Region. The results show that:(1)The effects of different land use types on soil bulk density is different, the improvement effects of soil structure of high wood and shrub is better than grassland and farmland, soil bulk density wan tend to decrease; the soil bulk density of high wood land is the smallest, the shrubbery followed, farmland is the biggest.(2)The soil moisture content of all four land use types are reduce by the increase of soil depth, the high wood land has the best water-holding capacity, the soil moisture content is the highest in high wood land whether in the whole soil profile or in every layers of the soil profile, the shrubbery followed, farmland is the worst.(3)The soil mechanical composition is mainly composed of silt particle in this area, the soil silt content hasn’t significant differences between whether all four land use types or each soil layer of the same land use type; the soil clay content of all four land use types are reduced by the increase of soil depth, the high wood land soil has the highest clay content to the whole soil profile, the shrubbery followed, farmland is the lowest; the soil sand content is in contrast with the clay.(4)Soil organic matter, soil nitrogen and soil phosphorus are all reduce by the increase of soil depth in all four land use types, and they are all dropping fast in 0~60cm soil layer, the content of soil potassium is not significant different between each soil layer; the soil nutrient content is different in different land use types, the organic matter, nitrogen, phosphorus and total potassium of high wood land are higher than other three land use types, the available potassium of farmland’s surface layer is the highest due to the effect of fertilizers; the order of four land use type comprehensive fertility is high wood land > shrub land > grassland > farmland.(5)The soil enzyme activity are significant differences between different land use types(at 95% level), four kind soil enzyme activity of high wood land are all in the highest level, the shrubbery followed, farmland is the lowest; the results show than the soil enzyme activity of soil surface layer have close interrelations.(6)There are close correlation between soil physical and chemical properties apart from soil silt particle; there are close correlation between four kind enzyme activity and soil nutrition indexes in soil surface layer too, most soil nutrition indexes significant positive correlation or very significantly correlated with four kind soil enzyme activity, but available potassium shows different degree negative correlation with four kind soil enzyme activity.更多还原