Abstract:

By means of field surveying, sampling and laboratory analyzing, it studied the contents, composition and properties of humus of 5 different tobacco-planting soil types in Zhangjiajie. The results showed that: the carbon content of humic acid was: yellow soil>paddy soil>rendzina>red soil>purple soil; the carbon content of fulvic acid was: yellow soil>paddy soil>red soil>rendzina>purple soil; the carbon content of humin was: rendzina>yellow soil>paddy soil>red soil>purple soil; the ratio HA/FA of 5 soil types was: rendzina>purple soil>paddy soil>red soil>yellow soil. The carbon content of loosely-combined humus was: yellow soil>rendzina>paddy soil>red soil>purple soil; the carbon content of tightly-combined humus was: rendzina>yellow soil>paddy soil>red soil>purple soil; the carbon content of stably-combined humus was: red soil>rendzina>yellow soil>paddy soil>purple soil; the ratio of loosely-combined humus/tightly-combined humus of 5 soil types was: purple soil>red soil>paddy soil>yellow soil>rendzina. These showed that humus in yellow soil was the richest; the quality of humus in purple soil was the best. The content and quality of humus in paddy soil or rendzina were moderate; red soil was the poorest. Each component of humus and soil organic matter was correlated significantly. The content of humic acid or loosely-combined humus would be used as an indicator of fertility in tobacco-growing soil.