垦殖对川西北高寒草地土壤理化性质的影响

为了解垦殖对川西北高寒天然草地土壤理化性质的影响,采用空间代替时间的方法,选择高寒草地垦殖年限为3a和10a的蔬菜地作为研究对象,以未开垦的天然草地作为对照,研究了不同垦殖年限下0—60cm土层土壤理化性质的变化特征。结果表明:人为垦殖导致天然高寒草地土壤养分含量和土壤理化性质显著下降,且随着垦殖年限的增加土壤质量进一步降低。垦殖10a后,0—60cm土层土壤容重、砂粒含量分别增加了21.1%和8.0%(p0.05),土壤含水量、有机质、全氮、速效氮、粘粒含量分别下降了38.4%,44.1%,39%,46.7%和19.2%(p0.05)。表层(0—20cm)土壤理化性质和土壤碳氮养分含量的降低最明显,随着土层的加深,土壤理化性质变化趋于减弱。0—20cm土层土壤大部分碳、氮养分的损失发生在垦殖前3a,而在底层(20—40cm和40—60cm)土壤垦殖前3a土壤碳、氮的变化未达差异水平,土壤碳、氮养分的损失主要发生在垦殖3~10a。

Effects of Reclamation on Soil Physical and Chemical Properties in Northwest Sichuan Alpine-cold Grassland

In order to understand the influence of reclamation on soil physical and chemical properties of alpine-cold grassland in northwest Sichuan,the method of replacing the time with the space was applied,and the vegetable lands in the alpine grassland which had been reclaimed for three and ten years were chosen as the research objects.In addition,the uncultivated natural grassland was taken as the control group to study the changing characteristics of the physical and chemical properties of 0-60 cm soil layers of different land reclamation years.The results showed that the artificial cultivation led to a significant reduction in soil nutrient contents,soil physical and chemical properties of natural alpine meadow,and soil quality further decreased with the increase of reclamation years.After ten years of reclamation,soil bulk density and sand content in the 0-60 cm soil layer were increased by 21.1％ and 8.0％,respectively;soil moisture,organic matter,total nitrogen,available nitrogen,and clay contents were decreased by 38.4％,44.1％,39％,46.7％,and 19.2％ respectively.Soil physical and chemical properties,and soil carbon and nitrogen contents were decreased most significantly in the surface layer (0-20 cm).With increasing soil depth,soil physical and chemical properties were weakened.The losses of soil carbon and nitrogen in the 0-20 cm soil layer occurred in the first three years of reclamation,while soil carbon and nitrogen in deeper soil layers (20-40 cm,and 40-60 cm) were not significantly lost in the first three years of reclamation.Losses of soil carbon and nitrogen mainly occurred in the first three to ten years of reclamation.