Effects Of Different Potassium Sulfate Levels On The Soil And Mineral Accumulation Of Flue-cured Tobacco

The potassium content in tobacco leaves is an important index in measuring the quality of flue-cured tobacco.However,the potassium content of tobacco leaves in Northern China is far different from that of foreign high-quality tobacco leaves.In the practice of tobacco agricultural production,the potassium content of tobacco leaves was mainly increased by increasing the level of potassium fertilizer put into the soil.Among them,the potassium sulfate is the most important and and the largest amount of potassium fertilizer.Therefore,a long-term localized fertilization experiment was designed in order to explore the changes of soil and flue-cured tobacco after applying different levels of potassium sulfate into soil,the soil type is brown soil.The experiment set up five treatments:NV（natural vegetation）,CK（no fertilization,continuous tobacco planting）,T1（K₂O input was 82.57kg/hm²,S input was 66.06kg/hm²）,T2（K₂O input was 165.07 kg/hm²,S input was 95.76 kg/hm²）,T3（K₂O input was247.57kg/hm²,S input was 125.46 kg/hm²）.In this study,this study mainly focuses on soil chemical properties,changes in bacterial communities,and growth of flue-cured tobacco,the findings are as follows:1.The effects of different potassium sulfate levels on soil chemical properties were studied.The application of potassium sulfate reduced the soil pH,and the pH of the soil treated by T3 decreased significantly,with a decrease of 3.77%.The application of potassium sulfate increased the content of potassium and sulfur in soil to different extents,and improved the supply potential and sulfur supply level of potassium and sulfur in soil.With the increase of potassium sulfate application level,the contents of exchangeable potassium,exchangeable hydrogen,exchangeable aluminum and total exchangeable acid in soil show a trend of gradual increase,the contents of exchangeable sodium,calcium,magnesium and total exchangeable base decrease to different degrees,aluminum saturation also shows a gradual rise.Correlation analysis showed that there was a significant correlation between soil pH and exchangeable acid,exchangeable base and aluminum saturation.The application of potassium sulfate to soil causes soil acidification.On the one hand,the application of potassium sulfate causes a decrease in the content of soil exchangeable base,and on the other hand,the content of soil exchangeable acid and aluminum saturation increase.2.The effects of different potassium sulfate levels on soil bacterial communities were studied.The uniformity and diversity index of bacterial community in T3 treatment increased.The relative abundances of Proteobacteria,Acidobacteria and Actinobacteria in each treatment were22.91%-40.76%,14.91%-39.78,10.14-20.44%,respectively.The top three bacteria in the tobacco planting soil community.The relative abundances of Proteobacteria,Acidobacteria and Actinobacteria were the top three bacteria communities in each treatment of tobacco-planting soil.The overall composition of bacterial dominant flora in tobacco-planting soil with different potassium sulfate levels changed little,but the number of bacteria in different phyla changed.Along with the increase of potassium sulfate level,the relative abundance of Acidobacteria showed a trend of decline,Proteobacteria and Actinobacteria showed an increasing trend.The application of potassium sulfate could change the soil bacterial community at the phylum level,and the change of soil bacterial community became more obvious with the increase of potassium sulfate application.3.The effects of different potassium sulfate levels on the growth of flue-cured tobacco were studied.Compared with the control,the total dry matter accumulation of flue-cured tobacco in T1,T2and T3 treatment increased to different degrees,with the increase rate of 56.84%,40.38%and 15.99%,respectively,but gradually decreased with the increase of potassium sulfate application level;The dry matter accumulation in all parts of flue-cured tobacco was expressed as leaf>stem>root.The application of potassium sulfate significantly increased the accumulation of sulfur,sodium,calcium,magnesium and aluminum in the roots,stalks and leaves of flue-cured tobacco as well as the whole plant.With the increase of potassium sulfate application rate,the total accumulation of potassium,sulfur and aluminum in flue-cured tobacco was gradually increased,and the total accumulation of sodium,calcium and magnesium was gradually decreased.4.Flue-cured tobacco is a potassium-loving crop.In order to improve the potassium content of tobacco leaves,the amount of potassium fertilizer（K₂O）is 2 to 3 times that of nitrogen fertilizer（N）.Our long-term positioning study showed that the high potassium sulfate level could improve the potassium content of tobacco leaves,but at the same time lead to soil acidification,and the biomass of tobacco plants is significantly reduced.Therefore,a comprehensive evaluation of the effect of potassium sulfate should be carried out to balance the advantages and disadvantages between the improvement of tobacco quality and soil degradation.