岷江上游干旱河谷区褐土不同亚类剖面及养分特征

PROFILE CHARACTERISTICS AND NUTRIENTS OF DRY CINNAMON SOILS IN DRY VALLEY OF THE UPPER MINJIANG RIVER

研究了岷江上游干旱河谷区典型地段海拔梯度上褐土的 3种亚类土壤剖面及其养分特征 .岷江上游干旱河谷褐土粘化作用较弱 ,矿物风化程度低 ;土壤呈碱性 ,pH值为 7.0～ 9.0 ,富含碳酸钙的石灰性褐土达 8.0～ 9.0 ;土壤表层有机质w在 32 .5 5～ 72 .78g/kg,整个土壤剖面中全氮w0 .78～ 4 .0 0g/kg ,全磷w0 .33～ 0 .6 8g/kg ,全钾18.2 4～ 2 1.6 8g/kg .总的来说 ,褐土潜在肥力水平较高 ,但由于土壤水分条件的限制 ,土壤潜在性肥力向有效性肥力转化的能力较差 ,致使土壤有效性肥力水平较低 .其中 ,土壤有效氮和有效钾w分别为 2 5 .5 7～ 2 4 4 .4 6g/kg和 6 78.2 4～14 5 3.6 5g/kg,同时由于土壤pH值和碳酸钙w较高 ,土壤中磷的固定较多 ,使得土壤有效磷w尤其偏低 ,为1.10～ 2 1.2 0 g/kg .干旱河谷高海拔地区的淋溶淀积型褐土的肥力水平高于中海拔地区的石灰性褐土 ,低海拔地区的燥褐土肥力水平最低 .土壤肥力随海拔高度升高而递增 ,决定了干旱河谷植被恢复从高海拔地区向低海拔地区更容易进行 .表 3参

The profile and nutrient characteristics of the dry cinnamon soils at different elevations in dry valley of the upper Minjiang River are presented. Results indicate that dry cinnamonsoils of this area is characterized by low weathering intensity and argillication, and high calcium carbonate Mass fraction with pH value ranging from 7.0～9.0. Mass fraction of organic matter, total nitrogen, total phosphorus and total potassium at different layers ranges from 32.55～72.78 g/kg, 0.78～4.00 g/kg, 0.33～0.68 g/kg, 18.24～21.68 g/kg, respectively, implying a relative high potential fertility. However, low soil moisture makes it difficult to transform the potential fertility into available fertility. As a result, available fertility in all of the cinnamon soils at different elevations is rather low. Mass fraction of available N and K ranges from 25.57 ～244.46 g/kg and 678.24～1 453.65g/kg, respectively. Mass fraction of available phosphorus is very low probably as a result of fixation due to high pH value and high Mass fraction of CaCO 3 . The result suggests that it would be easier to reforest at higher altitude than lower altitude. Tab 2, Ref 13