| Tobacco-planting soil pH is an important feature of the physical and chemical property of soil. It is closely related to the effectiveness of nutrient and the activity of soil microbe. Moreover, it has direct effect to the growth, appearance quality and chemical composition coordination of tobacco. Sichuan Province is one of the most promising tobacco producing areas in China. Thereby, timely understanding Sichuan tobacco soil acidity characteristics and analyzing the influencing factors of the soil acidification is very important to slow the process of soil acidification, reduce the economic losses caused by soil acidification and ensure the sustainable development of tobacco production in Sichuan.In this study, Tobacco-pi anting soil in Sichuan area (Liangshan, Panzhihua, Luzhou, Yibin and Guangyuan city) were selected as the research object and GPS was used to collect soil samples. For the change of the active acid and latent acid of Sichuan Tobacco-planting soil, descriptive statistical analysis and spatial analysis methods were used to analyze the spatial characteristics of the acidity of Tobacco-planting soil. Combination of the agricultural environment and the production situation of Tobacco-planting soil in Sichuan, we use correlation analysis, regression analysis, variance analysis and other methods to analyze the influence of soil physical and chemical properties (OM and CEC, EB and BS%), natural factors (altitude), human factors (plant years of the tobacco, the nitrogen fertilization way, land-use type) on Tobacco-planting in Sichuan. We also investigate acidity characteristics and the effect factors of Tobacco-planting soil of Sichuan. Analysis results indicate that:(1) Soil pH of Tobacco-planting soil in Sichuan was generally suitable for the growth of tobacco.① The mid-value of Tobacco-planting soil pH was 6.0. About 31.97% of the soil samples had pH within 5.5～6.5, which were the most suitable range for the growth of high-quality tobacco. About 25.07% of the soil samples had pH within 4.5-5.5 and 23.63% of the soil samples had pH within 6.5～7.5, which were good for the growth of high-quality tobacco.② From the comparison of different Tobacco-planting regions, soil pH in Yibin city was the lowest (5.2), the highest (6.7) was in Guangyuan city, the rates for the most suitable range (5.5～6.5) of panzhihua city and Liangshan prefecture were higher, Which were 52.78% and 43.40% respectively, while the Tobacco-planting soil pH of Luzhou and Yibin city were mainly range from 4.5 to 6.5, and Guangyuan city was mainly concentrated in 5.5 to 7.5. The pH of Tobacco-planting of Luzhou and Yibin were mildly acidic, Guangyuan city was neutral, while the soil pH of Panzhihua city and Liangshan prefecture were obviously better suited than than other three.③ In dynamic balance of active acid and latent acid of Tobacco-planting soil of Sichuan, soil pH was significantly positively correlated with soil exchangeable acid and non exchangeable acid. The correlation coefficient and regression equation of partial regression coefficient showed that the change of pH mainly depends on exchangeable acid (EA), non exchangeable acid (NEA) second. For commutativity acid (EA) the effect of H+ is greater than Al3+. The pH was mainly determined by H+in exchangeable acid (EA), which shows that the acid strength of Tobacco-planting soil in Sichuan was closely linked to exchange H+.(2) Spatial analyse about pH of Tobacco-planting soil.Tobacco-planting soil of Liangshan prefecture was suitable for planting flue-cured tobacco. Soil pH of Dechang was mainly between 4.5 and 5.5, which appears acid partially. Soil pH of yanyuan was mainly between 6.5 and 7.5, which was neuter. Soil pH of renhe district in Panzhihua city was mainly ranged from 6.5 to 7.5. While soil pH in ganyu town was lower than 5.5. Soil pH of gulin county was higher than 5.5. There were a few areas of northern xuyong county, whose soil pH was lower than 5.5. As a whole, the south part of the area is higher than the north part. The spatial distribution of soil pH in Yibin city was scattered and the plaque effect was obvious. Soil pH of parts of changning and xinwen county were lower than 5.5. Soil pH of wangcang was mainly between 6.5 and 7.5 and in jiange which was higher than 7.5.(3) Analysis about the influence factors of acidity characteristics Tobacco-planting soil.① Tobacco-planting soil pH was significant correlated with cation exchange capacity (CEC), total base (EB), and base saturation (BS%). Exchangeable Na+, Ca2+, Mg2+ and K+ were significant correlated with the soil pH.② The soil pH of Tobacco-planting showed a decreasing trend with the increase elevation, soil pH of Liangshan and Panzhihua was in the following order:pH1000～1400m> pH 1400～2000m>pH 2000～2400m. Luzhou and Yibin:pH 400～600m>pH 600～1000m>pH 1000～1400m, Guangyuan:pH400～600m> pH 600～800m> pH800～1000m.③ With the extension of planting years, pH of paddy soil, purple soil and yellow soil were decreased, especially the purple soil.④ The pH of Tobacco-planting soil has a negative correlation with nitrogen application rate. The higher nitrogen content in the soil, the lower pH value corresponding, the change of pH was small.⑤ Except Guangyuan city, the pH of Paddy soil is higher than the soil of dry land while under different land-use forms. |
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