Seasonal Dynamics And Fertility Evolution On Nitrogen,Phosphorus And Potassium In Soil Of Different Stand Ages In The Dry Valley Of Minjiang River

The dry valley of the upstream of Minjiang River is the area of atrocious weather. soil erosion and environment degradation,the problem is more and more serious.In order to use the soil enough and reasonable,which is regarded the ecosystem of sustainable development,firstly is the vegetation restoration,the second is to improve the fertility of the forest soil which is more important.In 1989,Pinus radiata was planted in the dry valley of the Minjiang River,now the Pinus radiata grow well,but the restoration of forest ecosystem not only in the vegetation restoration,but also in the fertility and its sustainer restoration.But so far,the reports on the effect of different plant year of Pinus radiata on soil nitrogen,phosphorus and potassium is very few. It's significant to have depth research about Pinus radiata plantations which can play its ecological,social and economic benefits sustained.Seasonal dynamics on soil nitrogen,phosphorus and potassium are researched to understand the changes in soil fertility beneath the Pinus radiata plantations of the dry valley of the Minjiang River. The research indicates the following conclusion.(1)It's obvious that the seasonal variation on the arid valley of Minjiang River of the Pinus radiata plantation soil total nitrogen,total phosphorus,available phosphorus,total potassium,available potassium,the result is July＞April＞January＞October.Plot 2 Maoxian Xiaomiaoshan's overall content is the highest,the second is Plot 1 Maoxian Xiaogou,Plot 8 Lixian Xuecheng Manshan is the final.(2)The soil moisture and organic matter content seasonal variation is basically the same as the nitrogen,phosphorus,potassium.Plot 2 Maoxian Xiaomiaoshan is the highest,the second is Plot 1,the final is the Plot 9 Lixian Xuecheng Shajin.With the increase in age,soil nutrient content showed a marked increase in the trend.(3)By the correlation analysis showed that:there are highly significant positive correlation among total phosphorus and available phosphorus,total potassium, bacteria,actinomyces,invertase,the correlation coefficients are:0.835,0.870,0.837, 0.781,0.833;among available phosphorus and total potassium,available potassium, bacteria,actinomyces,invertase,catalase,the correlation coefficients are:0.794,0.772, 0.824,0.772,0.889,0.860;among total potassium and actinomyces,invertase,the correlation coefficients are:0.789,0.809;among available potassium and catalase,the correlation coefficient is 0.950.There are significant positive correlation among total phosphorus and fungi,azotobacter,catalase,organic,the correlation coefficients are: 0.653,0.674,0.682,0.727;among available phosphorus and organic,the correlation coefficient is 0.754;among total potassium and bacteria,organic,the correlation coefficients are:0.642,0.695;among available potassium and bacteria,the correlation coefficient is 0.743.It can thus be seen:the number of soil microbed and soil enzyme activities have certain relevance,different microbed communities on different soil enzyme activities influences are different.There have relations between each other among the content of soil nitrogen,phosphorus,potassium and soil microbed and soil enzyme activity,they are interdependent and mutually influencing.(4)By the principal component analysis showed:different plant years in Pinus radiata plantations have different soil fertility:Plot 2＞1＞3＞4＞5＞6＞7＞10＞9＞8,soil fertility beneath the Pinus radiata plantation increase with the forest stand age.The conclusion indicate that Pinus radiata plantations are helpful to improve the soil fertility.So it's important to plant Pinus radiata in the dry valley of the Minjiang River to the process of vegetation restoration and the soil qulity raise.