Effect Of Ryegrass Application On The Characteristics Of Soil And The Quality And Yield Of Flue-cured Tobacco

The experiments were taken from 2005 to 2008 in order to study the effects of returning application ryegrass into field on soil remediation of tobacco plant and yield and quality of tobacco leaves in ChongQing WuLong. The main results as follows:1. Decomposition rule of ryegrassDuring the thirteen weeks after returning ryegrass into field, it released 60%-70% total carbon and 55%-65% total nitrogen in different depths. In the whole decomposition process, whether carbon or nitrogen, the fastest decomposition depth was 15cm. The fast decomposing period was weeks from 1 to 5, the slow decomposing period was weeks from 5 to 9 and from 9 to 13 weeks, the decomposition rate was flat.2. Effect of returning ryegrass into field on physical, chemical and biological characters of soilAs the increasing of ryegrass returning content, the soil bulk density decreased, the soil porosity, moisture content, organic matter and the pH value increased. The returning of ryegrass increased the content of available nitrogen, available phosphorus, available potassium, microbial biomass carbon and microbial biomass nitrogen, increased the soil urease activity, acid phosphatase activity, invertase activity and hydrogen peroxidase activity. Among them, the treatment of ryegrass returning 1500 kg /667m2 was the most obvious.As the increasing of ryegrass returning age, the soil bulk density decreased, the soil porosity, moisture content increased year by year and the soil urease activity and hydrogen peroxidase activity also increased. The effect on soil pH value, organic matter and available nitrogen content were more obvious. The improvement effect rules on soil available potassium, microbial biomass carbon and microbial biomass nitrogen content and soil invertase activity were not obvious.3. Effect of ryegrass returning into field on output value and quality of flue-cured tobaccoThe returning of ryegrass decreased the total nitrogen content of middle leaves, increased the nicotine, petroleum ether extract, the neutral aroma constituents and organic acid content and increased the content of the major and medium elements P, Ca, K, Mg and the trace elements Fe, Mn, Zn.The yield, output value, average price and superior middle proportion of tobacco leaves of each ryegrass returning treatment were higher than that of CK, and the yield, output value and average price of the ryegrass returning 1000 kg /667m2 treatment and the 1500 kg /667m2 treatment were better.In the ryegrass returning age treatments, the total nitrogen and the nicotine content were higher than that of CK, but as the age increasing, the increasing rate decreased and the nitrogen-nicotine ratio was lower than that of CK. Through many year continuous ryegrass returning, the petroleum ether extract content was increased. As the returning age increasing, the content of mineral elements of cured tobacco leaf was increased, for example P, K, Cu, Zn and so on.The organic acid content of each returning age treatment was higher than that of CK, among them, the organic acid of one year returning was the highest and secondly it was two year returning.The total content of neutral aroma constituents of the two and three year returning treatment was higher than that of CK except that the one year returning treatment was almost the same with that of CK, it showed that two year returning > three year returning > CK > one year returning. As the returning age increasing, the yield, output value and average price showed gradually increasing trend, among them, the three year returning treatment was the best.Combined with the above research conclusions, we presented that the returning application of ryegrass should be before transplanted 5 weeks, the suitable returning application content was 1000 kg～1500 kg /667m2 and the suitable depth was 15cm. The returning application of ryegrass should be many year continuous, in order to get to the purpose of repairing soil, improving the yield and quality of tobacco leaf and promoting the sustainable development of tobacco leaf production.