Nitrogen mineralization in Yunnan tobacco major growing soil

To determine the nitrogen mineralization in Yunnan tobacco major growing soil types,the different soil depths of purple soil,paddy soil and red soil were collected,the samples were incubated under aerobic condition at 20 ℃ and 30 ℃.The results showed that at the 0~20 cm and 20~40 cm depths,purple soil had a greater nitrogen mineralization value than the other two soil types,the red soil had the less value;On the contrary,at the 60~80 cm and 80~100 cm soil depths,the paddy soil had a greater nitrogen mineralization value while the purple soil had the less value.For the different soil depths,the soil nitrogen mineralization rate and value were as follows:0~20 cm20~40 cm40~60 cm60~80 cm,80~100 cm.Whatever the situation,the mineralization nitrogen value decreased with the increasing incubation days.The soil nitrogen mineralization rate and value incubated at 30 ℃ was higher than at 20 ℃.