陕西渭北旱塬典型苹果园土壤基本性质与微形态特征研究

Soil properties and soil micromorphological characteristics of the apple orchard in the Weibei Dry Highland,Shaanxi Province

通过对土壤微形态研究试图阐明陕西渭北旱塬长龄苹果园土壤的发育过程和质量演变。用偏光显微镜对LAS剖面不同发生层的薄片进行了观察和影像定量分析。结果表明:土壤形成物主要是粘土矿物、方解石和无定形Fe,Ap层中有大量次生方解石、次生粘土和蚯蚓粪粒,AB层与BC层方解石数量多且形态最复杂,黏土含量高,BC层可见大量淀积黏土,Ck/C层细晶与针状方解石较少,有少量残积粘土;土壤孔隙主要是孔道和填充孔隙。整个剖面从上向下微结构连续变化,反映了苹果地较稳定的土壤环境,也可能与人工苹果园长时间种植有关;不同发生层的矿物组合十分相似,石英(Q)和长石(Pl)占绝对优势,但C/F10μm值、不同矿物间的比例、颗粒形态等有明显差异。

This paper tries to illustrate the forming process of long-term （60 years） apple orchard soil and its micromorphological significance through the soil micromorphological analysis in Weibei Dry Highland , Shaanxi Province. According to field investigations , Samples of horizons in the LAS profile was were collected and soil properties were experimented in laboratory, soil micromorphologieal characteristics quantified by image analysis of thin sections in different horizons with the aid of a polarizing microscope and the Qwin software. Pedofeatures mainly consist of clay, calcite, and amorphous Fe. Ap horizon is characterized by abundant needle-shaped secondary-calcite, secondary-clay, and earthworm fecal pellet. AB horizon and BC horizon is characterized by the secondary-calcite of large quantity with various shapes and abundant clay, abundance of illuvial clay in BC horizon,less needle-like seconda- ry-calcite and a small amount residual clay in Ck/C horizon; The soil voids is characterized by channels and packed voids. The changes in succession of micromorphology with depth of the profile suggests that the soil environment has been maintained stable for quite a long period because of planting apple for a long time. Micromorphological observations of the thin sections show that the minerals assemblage of different horizons very similar, which is mainly composed of Q and P1. However, there are obvious differences in C/F10μm ratio, mineral content, and coarse features.