The Fertilization Model Of Flue-cured Tobacco Based On Spatial Variation Of Soil Organic Matter

The content of soil organic matter is closely related to the level of soil fertility.Although organic matter only accounts for a small part of the total soil,it plays a significant role in soil fertility.Besides the organic matter provides the necessary nutrients for the growth of flue-cured tobacco,as well as plays a role in improving the physical and chemical properties of the soil.However,the decomposition and accumulation of organic matter are highly susceptible to the influence of natural environment and human factors,and the content of soil organic matter varies greatly between different regions and even within the same region.So it is necessary to manage the tobacco-growing soil with different organic matter content by partitional management.At present,the application of organic fertilizer in flue-cured tobacco production has a good effect of stable production and quality improvement,and applying organic fertilizer against different organic matter backgrounds has become an inevitable step of applying fertilizer in a scientific way.Based on Arc GIS,different spatial analysis methods were used to analyze the spatial distribution characteristics of soil organic matter,and combined with its impact on tobacco quality,the fertilization model of Flue-cured Tobacco under different organic matter background was constructed.The results shows that:（1）Using the index function model,linear function model,trigonometric function model,spherical function model,Gaussian function model and inverse distance weighting method in the ordinary Kriging method of Arc GIS,the spatial distribution of soil organic matter in nine counties（districts）of Wuchuan,Daozhen,Zhengan,Fenggang,Meitan,Yuqing,Bozhou,Huichuan and Xinpu in the Middle East of Zunyi City was estimated,then field sampling verification.The results showed that the spatial distribution of soil organic matter content in Zunyi was the best fitted by trigonometric function model of ordinary Kriging method.The average interpolation error and root mean square error were the least,which were-0.03 and 7.91.Compared with the verification data set,the interpolation model of the inverse distance weighting method had a higher organic matter prediction value with an average error of 0.36;while the prediction results of the exponential function model,gaussian function model,linear function model and spherical function model of ordinary kriging method are relatively low,and the average errors are-0.15,-0.13,-0.12,-0.02,respectively.The content of soil organic matter in Zunyi was mainly moderate to upper,among which the content of organic matter in Daozhen,Zheng’an,Wuchuan,Fenggang and Yuqing in the eastern region was mainly 20～30 g/kg,accounting for71.04%of the total area of the region;in the central region,such as Meitan,Xizhou,Huichuan and Xinpu were mainly 30～40 g/kg,accounting for 66.84%of the total area of the region.（2）The spatial interpolation analysis of the main chemical quality of flue-cured tobacco leaves showed that the chemical indexes of most tobacco planting areas were within the requirements of high-quality tobacco,but the content of total sugar and reducing sugar in some areas such as Daozhen,Zheng’an and Wuchuan was relatively high,and the content of reducing sugars in southern Fenggang were relatively high,and the content of reducing sugar and potassium in Bozhou were relatively low.The whole survey also showed that the content of potassium and chlorine in tobacco leaves was insufficient in the whole study area,especially the content of chlorine.（3）Combined with spatial distribution correlation analysis and linear correlation analysis,found that there was a correlation between soil organic matter content and some chemical indexes of tobacco leaves in spatial distribution.There was a significant correlation with the ratio of nitrogen,total sugar,reducing sugar and sugar/alkali in tobacco leaves,and a significant positive correlation with nitrogen in tobacco leaves,and a significant negative correlation with the ratio of total sugar,reducing sugar and sugar/alkali in tobacco leaves.The results of linear correlation analysis showed that the content of potassium,chlorine,total sugar,reducing sugar and potassium/chlorine in the tobacco leaves were significantly correlated to soil organic matter,and the functional equations were y=0.0024x2-0.1582x+4.4515 R2=0.1055**.Potassium content decreased with increasing organic matter content.When organic matter content exceeded 32.96 g/kg,potassium content increased;y=0.0002x2-0.0174x+0.4529 R2=0.1264**,chlorine content decreased with increasing organic matter content,when organic matter content exceeded Potassium content increased at 43.50 g/kg;y=-0.0137x2+0.7873x+18.171 R2=0.0403*.The total sugar content increased with the increase of organic matter content.When the organic matter content exceeded 28.73 g/kg,the total sugar content decreased;y=-0.0145x2+0.8044x+12.215 R2=0.0566*,the reducing sugar content increased with the increase of organic matter content,When the organic matter content exceeded 27.74 g/kg,the reducing sugar content decreaseed;y=0.0041x2+0.0492x+9.8643 R2=0.0817**,and the potassium to chlorine ratio increaseed with the increase of organic matter content.（4）By comprehensively comparing the two correlation analyses,the correlation between the total sugar and reducing sugar content in the tobacco leaves and the soil organic matter content was better than other indicators,and the sugar content can better reflect the quality of flue-cured tobacco.According to the appropriate range of total sugar and reducing sugar content in tobacco leaves,the organic matter content of tobacco planting soil was divided into three grades,high organic matter content≥34g/kg,medium soil organic matter 23-34 g/kg,and low soil organic matter﹤23 g/kg.（5）Under the background of different organic matter content,with the increase oforganic fertilizer application,the content of available N and available P decreased,and the content of available K increased;under the background of medium organic matter,the content of available N and available K decreased,and the content of available P and available K increased in a fluctuating way;under the background of low organic matter,the content of available K decreased,and the content of other nutrients changed There was no significant difference between the two groups.（6）After applying organic fertilizer under different organic matter backgrounds,thetrend of the chemical composition of tobacco leaves varies greatly.The results showed that,under the background of high organic matter,the reducing sugar,the ratio of two sugars,the ratio of nitrogen to alkali,and the ratio of sugar to alkali were increased;the total sugar content remains unchanged;the total nitrogen,nicotine,and phosphorus decreased.Increased nicotine,potassium,reducing sugar,nitrogen-to-base ratio,and sugar-to-base ratio in the context of medium organic matter,while total sugar remained unchanged,and total nitrogen,phosphorus,and disaccharide ratio decreased;under low organic matter,Nicotine,phosphorus,potassium,total sugar,reducing sugar,the ratio of two sugars,the ratio of sugar to alkali all are unchanged,and the ratio of total nitrogen and nitrogen to alkali decreases.（7）The quantitative analysis of tobacco quality was carried out by using fuzzycomprehensive evaluation method.The correlation model between soil organic matter content and tobacco quality and yield was established.The results showed that Y _quality=0.0001X2-0.0074X+8.1243 R2=0.069,Y _yield=-0.1624X2+8.9423X+50.914R2=0.2161.Based on the regression equation of the application amount of organic fertilizer and the quality of tobacco leaves under different soil organic matter background,the fertilization model based on the quality index was preliminarily obtained.In the background of high organic matter,Y1=6.794+0.272X-0.80X2（0≤X≤1）,in the background of medium organic matter,Y2=6.850-0.529X2（0≤X≤1）,in the background of low organic matter,Y3=6.424+0.646X2（0≤X≤1）.