Effect of DensityDependent on Seasonal Variation of Soil NH+4-N and NO-3-N in Ligustrum lucidum Plantation

The effect of densitydependent of plantation on the characteristics of profile distribution and seasonal variation of soil NH+4-N and NO-3-N contents were studied based on the 7 a Ligustrum lucidum plantation in Jiangdu District of Yangzhou Municipality. The results showed that the contents of soil NH+4-N and NO-3-N in plantations with different densities decreased with soil depth, which also showed significant changes with different seasons. The content of NH+4-N in 3 densities was all higher in autumn and winter with the lowest value in the spring, and the content increased again in the summer. The NH+4-N content of the plantation with density of 2275 trees/hm2 was always higher than that of plantations with another two densities in the four different seasons. The seasonal change of NO-3-N content basically followed the same trend as NH+4-N content, with the lowest value in the spring, but there were significant differences among plantations with different densities. Contents of NH+4-N and NO-3-N were significantly correlated with soil moisture, temperature, and organic matter content(p＜005), and they were extremely significantly correlated with those factors in the summer (p＜001).