Effects Of Continuous Cropping Of Tobacco Soil Nutrients

After different tobacco Liuyang,Hunan, Guiyang, Hengnan and other tobacco-growing areas-cropping continuous cropping of tobacco soil of rice during the investigation sampling, the use of agricultural chemical analysis techniques to analyze the different continuous cropping of tobacco soil nitrogen, phosphorus and potassium plant the full amount must be three elements available contents and its impact ratio; study the effects of different continuous cropping tobacco soil exchangeable calcium and magnesium, effective sulfur, chlorine and other water-soluble content. The main result as follows:(1) With the increase of planting years, soil pH value showed a trend of rising, but the whole point of view, the change is small;(2) The content of soil organic matter in Liuyang and Guiyang city increased with the increase of continuous cropping years, and the soil organic matter content increased firstly and then decreased, and the maximum value appeared in the soil of 4-5 years of continuous cropping.(3) The contents of total nitrogen and total potassium in tobacco planting soil were relatively small, but the total phosphorus had the trend of accumulation. The available nitrogen, phosphorus and potassium showed a weak downward trend. The changes of available phosphorus and available potassium were not obvious.(4) The change of exchangeable Ca in the soil of different tobacco areas is different, and the general trend of the change is not a change in the different planting years. The effective sulfur was decreased and then increased, and the water soluble chlorine and the annual variation of the water soluble chlorine.(5) The soil nitrogen and phosphorus ratio showed a decrease trend, and nitrogen and potassium in the three representative regions showed different change law, phosphorus and potassium in the Liuyang area in the overall rise and fall trend, the Hengnan and Guiyang tobacco growing areas in the overall downward trend.