CHARACTERISTICS OF SOIL NITROGEN UNDER DIFFERENT LAND USE TYPES IN JI'AN CITY

This study was set up to characterize the effect of land use on soil nitrogen and its transformation in suburb soil in Ji'an city,soils under four types of land use were employed,i.e.,vegetable land(V),green land(G),forest land(F) and paddy field(P).The results showed that the greatest total nitrogen in top soil layer(0~10 cm) was in the paddy land,followed by vegetable land and green land,and the least was in forest land soil.The mean value from the greatest to the least was 964,769,646 and 564 mk·kg-1,respectively.In 10~20 cm soil layer,the average concentration of the total nitrogen was 769 mg·kg-1 in paddy soil,which is higher than that in the other three land use types.The average concentration of NH4+-N and hydrolysis N in 0-10 cm paddy soil layer is 99.2 and 119 mg·kg-1,respectively,far higher than that in other three land use types,while NO3--N in different land use types was similar,range in from 11.1 to 27.2 mg·kg-1.Soil NH4+-N,NO3--N and hydrolysis N concentration in 10~20 cm layer in different land use soils showed the similar changes as those in top layer(0~10 cm).The results also showed that the different nitrogen concentrations at 0-10 cm soil layer was greater than those at 10~20 cm soil layer in the same land use types.