北京地区2种类型土壤优先流染色形态特征及其影响因素

通过野外染色示踪试验结合室内图像解析技术,对北京地区2种类型土壤(淋溶褐土和潮土)进行了优先流染色形态特征及其影响因素研究。结果表明:(1)样地土壤用浓度为4g/L的亮蓝溶液27.3L染色后,淋溶褐土基质流深度均值为7.72cm,潮土为8.56cm,潮土优先流发生相对滞后;(2)淋溶褐土的优先流比、染色面积比、最大染色深度和长度指数均大于潮土,优先流现象更明显;(3)淋溶褐土优先路径集中区较多,侧向流较发达,且染色面积比和土壤深度相关性大于潮土,两者关系更密切;(4)2种类型土壤的土壤质地和土壤有机质与染色面积比显著相关(P0.01),直径为1~3mm的根长密度也和染色面积比呈显著相关(P0.05)。淋溶褐土优先流现象比潮土更明显,2种类型土壤对优先流染色特征影响较大的为土壤质地、土壤有机质和直径为1~3mm的根长密度。

Characteristics and Influencing Factors of Preferential Flow Dyeing Morphology of Two Soils in Beijing

The characteristics of preferential flow dyeing and the influencing factors of two soils (leached cinnamon soil and fluvo-aquic soil) in Beijing were studied through field dyeing and tracing combined with indoor image analysis. The results showed that:(1) After the soils were dyed with 27.3 L of a brilliant blue solution with a concentration of 4 g/L, the average depth of matrix flow was 7.72 cm in the leached cinnamon soil and 8.56 cm in the fluvo-aquic soil, and the preferential flow in the latter relatively lagged. (2) The dyeing ratio, the maximum depth of dyeing and the length index in the leached cinnamon soil were greater than those in the fluvo-aquic soil, which meant the preferential flow phenomenon in the leached cinnamon soil was more obvious. (3) More concentrated preferential path areas and more developed lateral flow were existed in the leached cinnamon soil, also the correlation between dyeing ratio and soil depth in the leached cinnamon soil was more obvious than those of the fluvo-aquic soil. (4) Soil texture and soil organic matter were significantly correlated with the dyeing ratio (P<0.01) in two soils. The root length density of 1~3 mm in diameter and dyeing ratio were significantly correlated (P<0.05). The preferential flow phenomenon in the leached cinnamon soil was more obvious than that of the fluvo-aquic soil. The soil texture, soil organic matter and the root length density of 1~3 mm in diameter were the major influencing factors for the characteristics of preferential flow dyeing in two soils.