Effect Of Adding A Combination Of Nitrogen And Phosphorus On Fine Root And Soil Microbes Of Machilus Pauhoi

Three years old Machilus pauhoi were used to carried out the experiment of adding a combination of N and P in Shunchang county,Fujian province.The fine root traits,soil physicochemical properties and soil microbial community in 0-20 cm topsoil of Machilus pauhoi stand were measured,to reveal preliminary the influence mechanism of fertilization on the relative growth rate of Machilus pauhoi,fine root traits,soil physicochemical properties and soil microbial community,and explored the synergistic effect of root,soil and microorganism on the growth of Machilus pauhoi.The main results were as follows:There was a significant difference in the response of adding.a combination of N and P by the relative growth rate of Machilus pauhoi in different seasons,which was largest in June.In the different treatments,the effect of N/P ratio between 10～12(NP2-NP3)on the growth of Machilus pauhoi was better.The fine root and soil and microorganism response to adding a combination of N and P in different seasons showed different adaptive characteristics,the SRL and SRA of 0-1mm and 1-2mm fine root arrived largest in June,which average diameter(AvgDiam)and tissue density(RTD)were highest in September.In general,the treatments of N/P ratio between 10～12 are the best for the construction of the main fine root morphology.Soil TN,soluble organic nitrogen(DON),Soil organic matter(SOM)and TP all were highest in September,and the overall effects of adding a combination of N and P on them also was better at the treatment of N/P ratio between 10～12.Bacteria,fungi,actinomycetes and microbial biomass carbon(MBC)and microbial biomass nitrogen(MBN)all reached their peak in September.In the all treatments,N/P ratio between 10～12 was the most beneficial to the growth of the three major microbial communities and the microorganisms’fixation on soil carbon and nitrogen nutrients.SRL and RTD of 0-1mm fine roots was the main fine root factors to affect relative growth rate(RGR)of the Machilus pauhoi.MBN was the main microbial factor affecting RGR.Soil TN,SOM and DON was the main soil factors affecting RGR.Combining all factors in our study,we found MBN,DON,and soil total phosphorus was the main environmental factor affecting RGR.