| Chinese fir is one of the most important timber species in China,as economy develops at full speed,the demand of timber increases unceasingly.The emergence of intensive management such as short rotation and full tree utilization brings out the fertility of Chinese fir plantations decline significantly,and impacts the timber production.In order to improve soil fertility,promote tree growth,achieve rapid growth and high-yield,a scientific measure of woodland fertilization is extremely important.Chinese fir is one of the most important timber species in Fujian Province.Most of the Fujian forest lands are the center of Chinese fir.This study was set up at 3 locations with three plot sites in each location in Fujian.These locations were topdressed in March 2007.Field investigation and laboratory analysis,the results proved that:â… (1)2-year-old forest land The Chinese fir stand aged 2 was tested on topdressing NPK+Zn or NPK+CuZn.The height and diameter at ground of Chinese fir, compared to control plots,increased by 13%-60%and 16%-24%,respectively. Topdressing copper NPK had the most obvious effect in the content of NPK.(2)3-year-old forest land Stand volume of tree with fertilization treatment was significantly higher than that in control plot,which increased by 16%-150%, respectively.Topdressing NPK+ Cu or Zn was optimum.Tree height and diameter were higher than the control,7%-41%and 13%-56%,respectively.(3)5-year-old forest land Compared with the control,stand volume of tree,tree height and diameter with Cu fertilization treatment increased by 52%,44%and 30%, respectively.(4)8-year-old forest land Stand volume of tree in control and fertilization treatments had increased significantly,with NPK+Zn fertilization treatment as optimum. Compared with the control,stand volume of tree,tree height and diameter with NPK+ Zn fertilization treatment increased by 52%,44%and 30%,respectively.(5)12-year-old forest land Topdressing NPK+Cu fertilizer was optimum. Compared with the control,stand volume of tree,tree height and diameter with Cu fertilization treatment increased by 26%,47%and 19%,respectively.(6)13-year-old forest land Stand volume of tree in control and fertilization treatments had increased significantly,with topdressing PK+CuZn as the best treatment. Compared with the control,stand volume of tree,tree height and diameter with PK+ CuZn fertilization treatment increased by 61%,76%and 63%,respectively.The content of zinc in branches increased significantly with Zn fertilization treatment.(7)17-year-old forest land Compared with the control,stand volume of tree, tree height and diameter with NPK fertilization treatment increased by 21%,24%and 26%,respectively.â…¡(1)The soil organic matter content in surface layer(0-20 cm)of two-year-old China fir increased significantly,NPK+Cu or Zn fertilization treatment had significant effects,which increased organic matter content by 25%-43%compared to control.For three-year-old China fir,the soil organic matter content in topdressing NPK+Zn treatment was the maximum,which increased by 23%-52%.For five-year-old China fir, the soil organic matter content in topdressing NPK+Cu was the maximum,which increased by 36%.For 12-year-old woodland,soil organic matter content had increased, but the effect of fertilizer application wasn't significant.For 13-year-old woodland,soil organic matter content increased significantly,but there were no significant differences among the treatments.For young woodland,the application of Cu and Zn had an obvious effect on the increasement of soil organic matter.(2)The available nitrogen content in the soil of two-year-old forest land with NPK+Cu or Zn fertilization treatment had significant effect,which increased by 28%-40%compared with the control.For 3-year-old woodland,the NPK content of the soil had increased significantly,NPK+ microelement fertilization treatment had the best effect on available nitrogen,which increased by 34%-50%compared to the control.For 8-year-old woodland,NPK+Zn fertilization treatment had the highest available nitrogen content in soil,which increased by 20%compared with the control.For 12-year-old woodland,NPK+Zn fertilization treatment had the highest available nitrogen content in soil,which increased by 14.5%-20.9%compared with the control.For 13-year-old woodland,N content has increased significantly,while K content and available pHospHorus in the surface soil increased slightly.(3)For 3-year-old woodland,the contents of copper and zinc with NPK+Cu or CuZn fertilization treatment increased by 17.1%-25.3%and 29.3%-78.6%,respectively. For 8-year-old woodland,the available Zn of topsoil had increased significantly,with Zn sulfate fertilization treatment increased by 32.5%-40.8%compared to the control. For 12-year-old woodland,the contents of Cu and Zn with NPK+Cu or Zn fertilization treatment increased by 13.5%-16.4%and 32.4%-22%,respectively.For 13-year-old woodland,the available zinc with PK+Zn fertilization treatment was the best,which increased by 21.9%-35.5%compared to the control.
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