Effects Of Green Manureapplication On The Improvement Of Tobacco-planting Soils And The Yield And Quality Of Flue-cured Tobacco Leaves

The experiments were carried out from 2005 to 2009 to study the effects of green manure application on the improvement of tobacco-planting soils and the yield and quality of flue-cured tobacco leaves in WuLong of ChongQing, Which could provide a theoretical basis to study low-carbon agriculture and build resource-saving, environment-friendly agriculture and promote the tobacco agriculture sustainable development. The main results as follows:1. Effects of returning green manure on the physical, chemical and biological characters of tobacco-planting soilsReturning green manure could improve the physical characters of tobacco-planting soils, The treatment returning green manures decreased the soil bulk density and increased the soil porosity and moisture content. As the returning application rates increased, the trend of soil bulk density was decreased, the soil porosity and moisture content increased. Among them, the green manure application rates returning 22500kg/hm2-30000kg/hm2 was better than others.Compared with the control, after returning green manure, the soil pH,the content of SOM, soil total nitrogen, soil akalytic nitrogen, soil available phosphorus, soil available potassium increased obviously. the green manure application rates returning 15000kg/hm2-30000kg/hm2 had actively effects on soil improvement and the combined effects of returning 22500kg/hm2 was better than others. Which showed that as the returning application rates increased, the available nutrient increased, but the green manure was restricted by the efficiency of release and mineralization, not the more the application rates ,the better.Compared with the control, after returning green manure, the soil microbial biomass carbon and microbial biomass nitrogen were higher than the control, and the soil microbial biomass carbon and microbial biomass nitrogen increased with the application rates increased, when the application rates increased to 30000kg/hm2,The content of microbial carbon and microbial nitrogen had a little decline, but the diversity with the application rates returning 22500kg/hm2 was not obviously. The dynamical changes of microbial biomass carbon and microbial biomass nitrogen take on bimodal curve, Microbial biomass carbon reached the peak at the rosette stage and the budding stage of flue-cured tobacco; however, the peak of microbial biomass nitrogen appeared at the rosette stage and the topping stage.After returning green manure, The activity of soil urease, acid phosphatase, invertase and catalase were higher than the control, The activity of the treatment returning geeen manure 22500kg/hm2-30000kg/hm2 were higher than others. returning geeen manure supply lots of organic nutrition, The promotion of enzyme activity was of great advantage to the turnover of organic matter and provision of nutrition to meet the needs of tobacco's regular growth. The activity of soil urease, acid phosphatase and catalase reached the peak at the busy stage and the budding stage of flue-cured tobacco, The activity of soil invertase increased after transplanting 60 days.2. Effects of returning green manure on the yield and the quality of flue-cured tobacco leaves.The agronomical characters of all the treatment returning green manure were better than the control, returning green manure increased the content of total sugar, reduction seger, petroleum ether extract, the neutral aroma constituents and organic acid of middle leaves, decreased the content of total nitrogen, increased the content of the major and medium elements P, K, Ca, Mg and the trace elements Cu, Fe, Mn, Zn.The yield, output value, average price and superior middle proportion of tobacco leaves of the treatment returning green manure were higher than that of the control, and the yield, output value and average price of the treatment returning green manure between 15000kg/hm2 to 30000 kg /hm2 were better than the others.All above showed that returning green manure could improve the capacity of keeping water and fertilizer of tobacco-planting soils. The tobacco plant could grow normally and the quality of tobacco leaves was good by returning green manure in the test field. So returning green manures should be several years continuous, in order to get to the purpose of repairing soil, improving the yield and quality of tobacco leaves and promoting the sustainable development of tobacco leaf production.