Effects Of Soil Bulk Density On Tobacco Growth And Soil Chemistry Properties Of Tobacco Growing

Tobacco as an important economic crop, soil bulk density play a crucial role in tobacco growing, nutrient absorption and utilization. Experiments with different soil bulk density were conducted to study the effects of soil bulk density on tobacco (choose Honghuadajinyuan as material) growth and soil chemistry properties of tobacco growing. The results showed that:Soil bulk density affected tobacco growth. Soil bulk density mainly affected the longitudinal growth of the root, with the increase of soil bulk density the tobacco root stretch ability decreased. The suitable soil bulk density for tobacco growth were between1.12g/cm3～1.27g/cm3. Soil bulk density had no significant difference in tobacco stem girth(except15～25d period, P<0.05). The rate of tobacco height growth for the treatment of D6, D5, D4were higher than D3, D2, D1. Soil bulk density had no significant effect in tobacco leaf blades under the same period, but had significant difference in leaf area of15days later after transplanting(P<0.01), and the treatment of D6, D5, D4were significant higher than other groups. The analysis result showed that tobacco fresh weight had no significant difference in each parts, but from the tobacco dry weight analysis result showed that had significant difference in root dry weight(P<0.05). Soil bulk density had no correlation with tobacco powdery mildew.Soil bulk density affected tobacco fibril growth. Soil bulk density had significant difference in tobacco root forks, root volume, root surface area(P<0.05). With the increase of soil bulk density the tobacco fibril of length, tips, volume, surface area, forks, average diameter were decreased, and had negative correlation with soil bulk density, coefficient of determination(R2) were between0.7～0.9. Tobacco fibril of length, tips, volume, surface area, forks, average diameter in treatment of1.12g/cm3were the highest, the lowest was1.59g/cm3treatment. The analysis results for fibril of root length, tips, volume, surface area distribution under differences root diameter in each treatments showed that, root length, tips, volume, surface area had the highest distribution between0.2mm～0.4mm. But the main distribution range were0.2mm～0.8mm,0.2mm～0.6mm,0.2mm～1.2mm,0.2mm～0.8mm respectively. Draw a conclusion that the main group of tobacco root structure was between0.2mm～0.4mm, soil bulk density had the most influence on it. With the soil bulk density decreased the root length, root tips, root volume, root surface area were decreased when the tobacco root diameter greater than2.8mm.Effects of soil bulk density on soil chemistry properties of tobacco-growing. With the decrease of soil bulk density, the soil pH of tobacco-growing were decreased, and soil available nitrogen were increased. Soil pH had negative correlation with soil bulk density, available nitrogen content had positive correlation with soil bulk density (Pears on correlation P<0.01). Soil available phosphorus content and cation exchange capacity had no change with soil bulk density. With the decrease of soil bulk density, the soil available potassium content increased, but had no significant difference in each treatments.