| In order to comprehensively understand the characteristics and trends of tobacco planting soil nutrients in Dali and improve the management level of fertilizer production. Based on Dali planting tobacco soil, select the soil p H, organic matter, hydrolytic nitrogen, available phosphorus, available potassium, exchange of calcium, exchangeable magnesium, available boron and available sulfur, water soluble chloride 10 indicators to build nutrient index system. Using the fuzzy mathematics principle to evaluate the IFI and research the characteristics of soil spatial and temporal variation. Then on the base of these, Nanjian as an example for the optimization of fertilization. All above are intended to exert the productive potential of Dali tobacco planting soil, to reach the goal of scientific balanced fertilization and to promote sustainable development. Research results show:1. Soil p H, available nitrogen, available phosphorus and available potassium were suitable, The content of organic matter exchangeable calcium and exchangeable magnesium were high, at the same time, the soil water soluble chlorine content and available boron were insufficient. Following the county district nutrient condition:All County Soil p H optimum, exchangeable calcium and magnesium is generally high, the content of other nutrients in different counties. The Yunlong County, soil nitrogen content is low, the content below 100 mg/kg soil accounted for 69.12%, Hydrolysis nitrogen content of soil in Dali City, Heqing County, Eryuan county and Jianchuan County are rich, The remaining counties most suitable. The content of soil available phosphorus in Yunlong County is lowest(18.85 mg/kg), nearly 70% of the soil phosphorus deficiency, the soil available phosphorus content in other counties is suitable. about the soil available potassium content, The content of potassium in Nanjian and Heqing is rich. The content of available potassium in Yunlong and Dali was slightly insufficient. The available potassium content of 30% soil below 80mg/kg, the other areas are suitable for the content At the same time, soil boron deficiency is a common phenomenon in all county, The phenomenon of Yongping County and Yangbi County of boron deficiency is more serious, the ratio of the soil with boron content of less than 0.5 mg/kg was more than 80%. From the point of view of the average content, the counties of soil available sulfur overall appropriate, but the coefficient of variation larger, lack and high sulfur content in soil accounted for a larger proportion. The soil water soluble chlorine content is generally low in all counties. The study on the comprehensive soil fertility showed that: Dali tobacco planting soil comprehensive fertility situation is good. 37.3% of the soil, its comprehensive fertility reached a moderate level(0.60 < IFI < 0.40), 43.5% of the soil IFI was greater than 0.6, Including Yangbi, Nanjian, Yong Ping, Yunlong IFI was greater than 0.8, belong to â… class,Heqing,Midu,Weishan,Binchuan,Eryuan belong to II class, Binchuan and Jianchuan belong toâ…¢, Dali for grade IV(IFI value is only 0.36). The partition result is similar to the result of cluster analysis.2. This study uses the statistical analysis software to analyze the spatial distribution characteristics of soil nutrients in Dali. The results showed that there was a strong spatial correlation between the soil index of Quanzhou tobacco planting and water soluble chlorine, the distribution characteristics of nutrients and spatial variation trend were significantly correlated. Because of the influence of the random factors such as fertilization and tillage, the water soluble chlorine content in the soil is relatively low. Using Arc GIS software to make the indicators of spatial distribution were show that: The spatial distribution pattern of soil p H, exchangeable calcium and exchangeable magnesium is similar, shows the Northwest- the Middle East region to the southwest direction of the trend of lower. The distribution characteristics of soil organic matter and alkali were similar, which showed a decreasing trend in the northeast to the southwest. Available phosphorus and available potassium showed a higher trend in the Northeast-southwest, to the northwest, Southeast began to reduce. The spatial distribution characteristics of soil available boron content is the trend of increasing from West. Jianchuan, Binchuan, Jianchuan, Weishan has a small area of high sulfur soil.The distribution of soil available sulfur and boron Similar is similar, both of them are for the western region to the East, North and South three directions increased gradually. Soil water soluble chlorine variation is not obvious, because of its variation is mainly caused by random factors, the distribution characteristics of tend to small pieces of variation, gradient distribution.3. The trend of inter annual variation of soil nutrients showed that in recent 12 years, the value of soil nutrients in Dali showed an increasing trend. Among of them, the amount of effective sulfur content increased at most, The growth rate reached 77.1%, followed by exchangeable magnesium(38.5%), exchangeable calcium(29.3%), organic matter(21.8%), and the other indicators increased by 20%. As the nutrient content increased, the coefficient of variation showed different degrees of increase, Regional indicators of differences was expand. From the distribution frequency, the proportion of soil available boron, effective sulfur, water soluble chlorine that in the appropriate range was increased; other indicators of soil distribution change is mainly increasing in the range of high content.4. Fertilization technology optimization test results show that: in the production,on the basis of conventional fertilization, the 15% reduction of nitrogen had no significant effect on the yield and output value of tobacco leaf. Appropriate adjustments to the magnesium fertilizer, boron and other trace nutrient inputs can be in ensuring the yield of tobacco leaves to improve the proportion of superior tobacco, tobacco production efficiency increased. |
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