Organic Material Fertilization's Effect On Nitrogen Dynamics Of Tobacco-planting Soil And Functional Diversity Of Tobacco Rhizosphere Microorganism

Tobacco quality and output are two key factors in tobacco industry.Large-scale application of chemical fertilizer has caused tobacco-planting soil quality worsening,which has severely restricted the enhancement of flue-cured tobacco quality.Researches show that,organic materials are of great significance for tobacco-planting soil amelioration.As important carbon and nitrogen sources of soil microorganism,organic materials can exert an influence on soil nutrient element transformation by regulating functions of microbial communities.With the tobacco-rice planting system soil in south Hunan as the object,this research has applied the method of combining field experiment with indoor cultivation experiment under the circumstance of equal nitrogen,to research the influence of different organic materials and cake fertilizer dosage on tobacco rhizosphere microbial function diversity and nitrogen dynamics,and discussed fertilization measures suitable for tobacco production so as to provide guidance for tobacco farming and production.Main research results are as follows:1.Results of laboratory culture experiment show that,Fertilizing straw into high organic-material soil can regulate soil nitrogen release and maintain soil's high fertility level.Fertilizing cake fertilizer can promote the release of soil nitrogen.But in low organic-material soil,Fertilizing straw can promote the release of soil inorganic nitrogen,and cake fertilizer can regulate the release of nitrogen to achieve the effect of maintaining soil fertility.Straw and oilseed rape treatment can significantly improve soil urease activity.In low organic-material soil,addition of organic material can improve soil sucrose activity.It influences the activity of soil microorganism in sequence of straw treatment,oilseed rape stalk and cake fertilizer.Results of further principal component analysis show that,straw treatment and rape stalk treatment are the largest contribution factors to the first principal component.This indicates that the level of carbon nitrogen ratio in materials is an important factor to influence microorganism's utilization of carbon source in soil.2.Different organic-material experiment results show that,Organic material fertilization can regulate and control the release of nitrate nitrogen in the rhizosphere soil,Fertilizing organic materials has significantly improved the urease activity of rhizosphere microorganism but has no remarkable impact on catalase.significantly improved the metabolic activity and function diversity of tobacco rhizosphere microorganism.Results of principal component analysis show that,metabolic characteristics of rhizospheric microorganism with different treatments are different in tobacco growth period.This is mainly reflected in differences of rhizospheric microorganism's utilization of sucrose mortierellate.Fertilizing straw,rape,and cake fertilizer can coordinate chemical components in tobacco,and improve3.Results of cake fertilizer dosage experiment show that,with the increase of cake fertilizer dosage,the release capacity for soil nitrogen control will weaken,and functional diversity of tobacco rhizosphere microorganism and urease activity will reduce.Treatment of low cake fertilizer dosage can effectively control the release of soil nitrogen,and maintain relatively high urease activity and microbial activity of rhizosphere soil.T4 treatment(15%cake fertilizer +85%special-use base fertilizer)has improved AWCD value of rhizospheric microorganism during the tobacco growth period,and increased the diversity index of rhizospheric microorganism.Principal component analysis show that,rhizospheric microorganism's utilization of carbon source with different treatments in different periods of tobacco growth are variable.Varieties of carbon source having differential effect on rhizospheric microorganism mainly are:saccharides,amino acids and carboxylic acids.Comparing with tobacco economic characters,cake fertilizer processed by T4 has the optimal effect on providing guidance in tobacco production and fertilization.