The Research Of Fertility Status And Fertility In Tobacco Planting Dryland

Aiming at the problems of soil nutrient imbalance, structural damage and the decline in fertility, which caused by the increased fertilizer application level of dryland planting tobacco, this study adopts laboratory sampling and field plot experiment to explore the correlation between soil fertility and tobacco quality and yield; by planting green manure then turning over it to the soil and applying organic fertilizer and microbial agents in winter, To study the effects of different fertilization techniques on soil fertility, structure and quality of tobacco leaves under different soil fertility conditions. The results show that:1. The pH of the tobacco soil in the bases was suitable, and the average is 6.26; the available trace elements and available sulfur content were rich; exchangeable calcium and water soluble chloride content were low, among which the average of exchangeable calcium content is lower than 5 cmol/cat, the average of exchangeable magnesium content is lower than 1 cmo/cat, the others vary due to the nutrient fertilization base, soil parent material, climate conditions. The fertilizer level of Huayuan, Longshan, Sangzhi bases was high, and soil available nitrogen, phosphorus, potassium content was rich, but the cation exchange capacity, potassium content was generally low, with the poor soil buffer capacity, especially the difficulty of the soil nitrogen elements regulation, which resulting in big tobacco production but poor quality; and the level of tillage of Shimen, Hefeng and Wushan bases was low due to the high altitude,and the degree of damaged soil physical and chemical properties was low, the available nutrient content was not high, but the content of organic matter, cation exchange capacity was high, integrated soil fertility level, nicotine, reducing sugar, potassium, chlorine was appropriate, but the production needs to be improved. Soil texture except Longsan, Huayuan bases being loamy clay, other bases belong to silty clay.2. With the increasing of organic fertilizer,soil alkali hydrolyzable nitrogen,available phosphorus and slow-release potassium content also increased, during the period of dome stage in Sangzhi, soil alkali hydrolyzable nitrogen content of low, medium and high organic fertilizer treatments were increased by 26.5%,30.6%,30.6%,compared with the control. Soil pH also has a certain improvement, but the effects of medium amount of organic fertilizer on soil nutrient coordination was the best. High quality organic fertilizer can better improve soil nutrient content than low quality organic fertilizer did,which had a significant effect on improving soil fertility of Sandzhi, while impact of low quality organic fertilizer in regulating base soil nitrogen supply levels and improving soil potassium content was more obvious in Hefeng.3. Green manure pressure can hold part of the soil available nutrients and organic matter, reduce migration rate of nutrients especially nitrogen, and coordinate soil nutrient balance. The improvement of pH of the different varieties of green manure in weak acidic tobacco soil ranks as Cruciferae> Poaceae> Legume; poaceae green manure pressure greatly improved soil organic matter in the early stage of Flue-cured tobacco, especially on soil available nutrients and physical property modification, water holding capacity of ryegrass soil was increased by 0.49%, bulk density decreased 0.05 g·cm-3; and Cruciferae with legume green manure pressure treatment contributes more to the soil organic matter during the flue-cured tobacco growth period.4. Tobacco-fertilizer yearly cropping pattern can improve soil nutrient fertility, acid-base environment, and physical structure to some extent in the dry land area. After Chinese milk vetch rotation,soil fertility level is too high, especially the difficulty of controlling nitrogen level, the soil alkaline nitrogen content of the flue-cured tobacco is increased by 37.5% compared with the control; the supply of soil phosphorus and potassium nutrients was adequate under tobacco-gramineous green manure rotation, the nitrogen level was suitable, and integrated soil fertility level was high.5. After the application of microbial inoculants,soil available nitrogen, phosphorus and potassium increased in varying degrees, but the flue-cured tobacco growth showed a slight downward trend. The application of microbial inoculants can certainly affect the soil microbial community and amount, the number of soil bacteria of microbial inoculants application treatments during flue-cured tobacco mature period was higher than that of the control, the order of quantity of soil fungi from high to low was T3>T2>T1>CK, and the number of actinomycetes and the number of bacteria was contrary. The soil microbial biomass carbon and nitrogen dynamic change trend and tobacco nitrogen demand curve coincide.