黑河绿洲区耕作影响下的土壤粒径分布及其与有机碳的关系

Research on soil particle size distribution and its relationship with soil organic carbon under the effects of tillage in the Heihe oasis

选取黑河绿洲区典型土壤类型为研究对象,分析耕作对土壤粒径分布及其与土壤总有机碳、活性有机碳、惰性有机碳关系的影响。结果显示:非耕地(灰钙土、灰褐土、栗钙土)转变为耕地后,改变了10～50μm粗粉粒、50～250μm细砂粒、250～1000μm粗砂粒的含量,对<5μm的粘粒含量影响小。而风沙土变为耕地土壤后,土壤颗粒出现了细化现象。土壤粒径分布的变化也波及到了土壤颗粒与有机碳的关系,耕地与非耕地中存在异同点。相同之处在于,以50μm作为分界点,土壤总有机碳、活性有机碳、惰性有机碳与<50μm的粉粒、粘粒土壤颗粒含量呈正相关,与>50μm的砂粒呈负相关。不同之处为:耕地中土壤有机碳仅与5～10μm、10～50μm、50～250μm有关;非耕地中土壤有机碳与<1μm、1～5μm、5～10μm、10～50μm、50～250μm、250～1000μm的含量有关。分析表明,耕作是引起土壤活性有机碳增加及土壤有机碳与土壤粒径之间的关系发生变化的内在原因。

Effects of tillage on soil particle size distribution and its relationship with total organic carbon（TOC）,active organic carbon（AOC）,and nonactive organic carbon（NOC） are analyzed in the central Heihe Valley.Results show tillage significantly alters the percentage of particle sizes of 10-50 μm,50-250 μm,and 250-1000 μm while the uncultivated plots（sierozems,grey cinnamon soil,chestnut soil） are changed to the cultivated plots（alluvial soil and irrigated desert soil）,respectively.And the percentage of soil particle size presents a thinning trend while aeolian sandy soil is changed to alluvial soil and irrigated desert soil.These changes also affect the relationship between soil particle size and soil organic carbon.Statistical results between soil particle size and soil organic carbon（TOC,AOC and NOC） show the similarities and differences at the cultivated and uncultivated plots.The similarity has a significantly positive（P0.01 or P0.05） correlation with soil silt-and clay-size fractions under 50 μm size and a significantly negative relation（P0.01 or P0.05） with sand fractions over 50 μm size.The difference is that there is significant relationship between soil organic carbon and particle sizes of 5-10 μm,10-50 μm,50-250 μm at the cultivated plots and particle sizes of 1 μm,1-5 μm,5-10 μm,10-50 μm,50-250 μm,and 250-1000 μm at the uncultivated plots.It is found that tillage increased AOC content and became the intrinsic reason of relationship change between soil organic carbon and particle size.