攀西山区植烟土壤pH和有机质含量特征与关系研究

pH和有机质是土壤肥力的重要指标，也是烤烟优质高产重要因子。本文以攀西山区4个烤烟主产县的19个典型烟田的剖面为代表，合计采集了75个发生层样品，分析了有机质和pH特征及其关系，旨在为攀西山区烟田土壤改良和施肥提供科学指导。结果表明：①耕层pH变幅为4.11~7.89，平均为6.25，总体上处于植烟适宜级别（pH 5.5~7.0），但有21.05%样点处于偏酸（pH<5.5）级别；②耕层有机质变幅为9.20~47.80 g/kg，平均为21.64 g/kg，但仅26.31%的样点处于适宜植烟级别（10~40 g/kg）；③不同成土母质的耕层有机质含量由高到低依次是风化坡积物、残积物>第四纪红黏土>沟谷堆积物，前两者间没有显著差异，但均显著高于后者；④土壤pH和有机质之间呈负相关关系；在剖面分布上，pH随着深度的增加而增大，而有机质表现出明显表聚现象，向下急剧降低。

Characteristics and Relation of pH Values and SOM Contents of Typical Tobacco-growing Fields in Panxi Mountainous Area

pH and SOM are two important indicators of soil fertility which also influence or decide the yield and quality of flue-cured tobacco. In this paper, 75 horizon samples of 19 typical tobacco-planting fields in 4 main tobacco-producing regions in Panxi mountainous area were selected, and pH values and SOM contents were measured in order to guide for reasonable soil improvement and fertilization. The results showed that pH of the ploughed layers ranged from 4.11 to 7.89 with an average of 6.25, generally suitable for tobacco planting (5.5-7.0), but 21.05% of the typical fields were acid (pH<5.5) and needed to be improved. SOM contents of the ploughed layers ranged from 9.20 g/kg to 47.80 g/kg with an average of 21.64 g/kg, only 26.31% of the typical fields were suitable for tobacco planting (10-40 g/kg). SOM contents of typical fields with different parent materials were in an order of weathered slope washes and saprolites>quaternary red clay>gully deposits, and no significant difference between the first two materials but they both were significantly higher than the latter. pH was significantly negatively correlated with SOM. pH decreased with the increasing soil depth, while SOM showed obvious surface accumulation, and reduced sharply downwards.