东北典型黑土耕层颗粒组成与腐殖质层厚度的关系

Relationship between depth of humus horizon and particle size composition in tillage horizon of the typical black soil in Northeastern China

土壤颗粒组成是影响土壤肥力的主要物理性质之一。为了了解东北黑土腐殖质层厚度与土壤颗粒组成的关系,通过在东北典型黑土区选择典型坡面,调查不同地貌部位土壤腐殖质层厚度,测定耕层土壤的颗粒组成,分析腐殖质层厚度和耕层土壤颗粒组成随地貌部位的变化趋势,以及土壤颗粒组成与腐殖质层厚度的关系。结果表明:土壤腐殖质层厚度由上坡至坡脚有显著增加的趋势,沙粒质量分数在坡顶较低,但耕层土壤颗粒组成随地貌部位的变化趋势不明显;土壤腐殖质层厚度和颗粒组成受局部地形变化的影响较大;耕层土壤颗粒组成主要由腐殖质层厚度决定,随着腐殖质层厚度的增加,黏粒和粉粒质量分数呈指数曲线增加,而砂粒质量分数则呈指数曲线递减,当腐殖质层厚度大于60 cm后,耕层土壤颗粒组成随腐殖质层厚度的继续增加变化缓慢。研究结果对于了解东北黑土区土壤侵蚀导致的土壤退化机制有一定的帮助。

Soil particle size distribution is one of the key physical factors regulating soil fertility.To quantify the relationship between the depth of humus horizon and particle size composition,this study made a field survey of the depth of humus horizon and measured soil particle size in tillage horizon on a typical slope farmland in the black soil region of Northeastern China.Depth of humus horizon increases from up slope to down slope,but this trend is often interrupted by local topographic changes.There are no consistent trends in particle size composition from upper slope to lower slope,except that the sand content is higher at top slope than in other slope positions.Soil particle size composition of tillage horizon is significantly related to the depth of humus horizon.Both clay and silt contents are exponentially increased with the depth of humus horizon,and the sand content is exponentially decreased with the depth of humus horizon.However,when the depth of humus horizon was thicker than 60 cm,the particle size composition did not change significantly with further increasing depth of humus horizon.