Fungal Driving Mechanism Of Typical Organic Materials To Improve Soil Fertility Of Low-Efficient Camellia Oleifera Plantation

As an important woody edible oil tree species in China,Camellia oleifera has both economic and environmental benefits.The soil fertility of the main Camellia oleifera producing areas in the low hills in the south is seriously degraded due to extensive management,so improving the soil fertility of Camellia oleifera plantation is of great significance for promoting the economic benefits of Camellia oleifera plantation and maintaining the ecosystem functions of the forest.In this study,the research method of location plot and culture experiment was adopted.Plot experiment added tea fruit husk and rice straw as the main material(1kg/C),and cooperate with the EM bacteria agent(mother solution diluted 10 times)set up six processing: no carbon ource added(CK),add the Camellia oleifera shells(CS),add the rice straw(RS),according to the quality such as add Camellia oleifera shells and rice straw(CSRS),add Camellia oleifera shells + 50 ml EM bacteria agent(CSEM)and add the rice straw + 50 ml EM bacteria agent(RSEM).In the simulated culture experiment,organic materials were added at 8g/kg dry soil,set seven processing: no carbon source adding(CK),add the Camellia oleifera shells(CS),add Camellia oleifera shells and the adjusting C/N/P for 60/7/1(CSr),add the rice straw(RS),add the rice straw and the adjusting C/N/P for 60/7/1(RSr),according to the quality such as add Camellia oleifera shells and rice straw(CR)and by quality to add Camellia oleifera shells and rice straw and the adjusting C/N/P for 60/7/1(CRr).To explore the effects of typical organic materials(Camellia oleifera shells and rice straw,etc.)on improving soil fertility of barren Camellia oleifera forest,in order to provide theoretical basis and date support for the practical application of Camellia oleifera shells in forest restoration.The main research results are as follows:(1)The culture experiment showed that the average daily apparent mineralization amount of the organic material with a regulated C/N/P of 60/7/1 was higher than that without the regulated dosing ratio.The average daily apparent mineralization of rice straw was higher than that of mixed straw and shell,and higher than that of mixed shell.The apparent cumulative mineralization amount of rice straw treatment was higher than that of Camellia oleifera shells treatment.On this basis,the apparent cumulative mineralization amount of organic material with C/N/P of 60/7/1 was higher.(2)Develop experimental study shows that adding organic material markedly enhance soil carbon invertase(CBH and BG),nitrogen invertase(LAP and NAG)and phosphorus invertase(ALP)enzyme activity,organic material and the adjusting of carbon,nitrogen,phosphorus stoichiometric ratio further enlarge this enhancement effect;The enzymatic activity logarithm ratio of microbial carbon,nitrogen and phosphorus invertase showed that the addition of organic materials was better than that of Camellia oleifera shells to alleviate the effect of low phosphorus in the soil.(3)The annual fluctuations of nitrogen,phosphorus and potassium in the leaves of Camellia oleifera were relatively small.Among them,the nitrogen content in leaves was higher in summer and autumn,phosphorus content was higher in spring and potassium content was higher in spring and autumn.In spring,summer,autumn and winter,the N/P of the leaves were 13.7 – 14.8,19.2 – 20.8,17.4 – 19.3 and 13.9-15.8,respectively.According to the chemical law of the element ratio of the leaves,when the N/P < 14,N/P > 16 and N/P were between 14 – 16,the plant growth was restricted by N,P and both.The spring and winter of Camellia oleifera in the study area were limited by nitrogen and phosphorus nutrients.In summer and autum,Camellia oleifera is mainly restricted by phosphorus.(4)The dominant fungal communities of each treatment in the culture experiment included Sordariomycetes,Tremellomycetes and Eurotiomycetes.The Mortierellomycetes community had inhibitory effect by adjusting the measurement ratio of organic materials(the Mortierellomycetes was only the dominant population in the later stage of culture without adjusting the measurement ratio of organic materials).At the later stage of culture,the fungus richness index of the treatment with mixed materials was significantly higher than that of the treatment with straw and shell alone and CK,indicating that the mixed exogenous carbon source was conducive to the maintenance of soil fungal diversity.(5)The soil fungal community structure treated with Camellia oleifera shells was similar to that of CK in the field experiment,indicating that the soil microbial community structure of Camellia oleifera plantation could be maintained to the maximum extent while organic nutrients were input,which was conducive to the stability of the ecosystem of Camellia oleifera plantation.The addition of EM bacteria agent did not change the soil fungal community structure,and its effect could not be determined in a short time of monitoring.To sum up,the return of Camellia oleifera shell and rice straw as organic materials to forest can improve soil fertility,activate and enhance soil fungal activity,increase soil carbon,nitrogen and phosphorus invertase activity,and maintain the stability of soil microbial ecosystem in Camellia oleifera forest.In the process of forest restoration,attention should be paid to adjusting the stoichiometric ratio of carbon,nitrogen and phosphorus to supplement the soil nitrogen and phosphorus nutrients,and to remove the nutrient restrictions in the growth process of Camellia oleifera.