东北黑土区典型坡耕地土层厚度及退化程度分析

Analysis of the soil thickness and the degradation degree of the typical slope farmland in the black soil region of Northeast China

黑土区坡地退化不仅降低水土资源质量,而且造成生态环境恶化。探索东北黑土区坡耕地土层厚度及退化规律,为区域坡地水土流失防治提供理论支持。选取吉林东辽杏木试验基地内坡度6°和10°2个坡面为研究对象,以已有水保措施的8°坡耕地中位作为对照,研究黑土区坡耕地不同坡位土层厚度和土壤退化程度。结果表明:1)研究区土壤厚度20 cm为临界厚度,小于临界厚度则说明该坡位受侵蚀影响,正在退化;2)6°和10°坡地土层厚度、土壤物理性质、土壤养分状况和产量均比对照坡地差(P<0.05),且10°坡面土壤理化性状优劣排序为坡下>坡上>坡中,6°的变化规律为坡下>坡中>坡上;3)土层厚度越薄,土壤理化性质和产量状况就越差;4)研究区10°和6°坡地各坡位退化程度分5类,第1类土壤退化程度偏弱,产量较好,第2类特点为土壤含水量较低,速效磷和速效钾含量较低,第3类特点为密度较大,有机质质量分数较低,第4类土壤理化性质良好,产量高,第5类特点为含水量极低,密度极大,养分含量极低,产量低下。综上,黑土区坡耕地土壤厚度削减程度及退化程度较严重,6°和10°土层厚度变化和退化规律不同,该结果可为黑土区坡耕地退化防治提供理论支撑。

[Background]The degradation of the sloping farmland in the black soil region not only reduces the quality of the land and the water resources,but also causes the deterioration of the ecological environment.This study explores the change rule of the soil thickness and the degradation of the sloping farmland in the black soil region of the Northeast China,and it provides theoretical foundation for the prevention and control of the soil erosion on sloping field.[Methods]6°and 10°sloping farmlands in Dongliao county of Jilin province were selected as the main research objects,and a 8°farmland with soil and water conservation measures implemented in the near area was as CK field.We studied the degree of soil erosion by measuring the thickness of soil and investigated the degradation at different slope positions on the slope farmland in the black soil region via corresponding mechanical and chemical methods.We employed Excel,SPSS20.0,ANOVA to process data and cluster analysis for the classification of the soil degradation.[Results]1)The place with cultivated soil layer of 20 cm was the critical point,and when the soil thickness was<20 cm,it meant that the soil erosion was strong on this sloping position.2)The soil physical and chemical properties and the soil thickness statuses of the 6°slope and the 10°slope were significantly worse than those of the CK field(P<0.05),and the soil physical and chemical properties rank of the 10°slope was as“bottom>top>middle”,and the rank of the 6°slope was as“bottom>middle>top”.3)The thinner the soil thickness was,the worse the physical and chemical properties and the yield were,that meant the more serious the erosion was,the more serious the degradation was.4)The soil degradation degree of the 6°slope and 10°in the study area were classified into 5 types,type 1 was characterized by the slight erosion and the relative high yield;type 2 was characterized by the low moisture content and the low rapidly available phosphorus and rapidly available potassium content;type 3 was characterized by the high bulk density,the low organic matter content;type 4 was characterized by the good soil physical and chemical properties and the high yield,and type 5 was characterized by the low moisture content,the high bulk density,the low nutrient content and the low yield.[Conclusions]The reduction degree of soil thickness and the degradation degree in the study area are relatively serious,and the reduction and degradation rule between the 10°slope and the 6°slope are different,and the results may provide theoretical support for the prevention and control of the degradation of the sloping farmland in the black soil region.