郴州植烟土壤pH空间分布及影响因素初探

为探明郴州植烟土壤酸碱度状况，于2015年在郴州烟区采集土壤样品1055个，利用多元统计学和地统计学方法分析了郴州植烟土壤pH值空间变异及其影响因素。结果表明:郴州植烟土壤pH均值为7.00，变幅为4.47~8.14，pH值小于5.5的植烟土壤占10.91%，pH值大于7.0的植烟土壤占62.37%；各县植烟土壤pH均值在5.58 ~ 7.26。植烟土壤pH值空间结构为指数模型，空间变异主要由人为因素决定（如使用石灰和钙镁磷肥等），空间分布呈现西南高、东北低的格局。偏最小二乘回归的分析结果表明，交换性钙、粉粒、全磷、全氮、有机质、碱解氮、阳离子交换量（CEC）和交换性镁是影响植烟土壤pH值的主要因素，8项指标对植烟土壤pH值的累计解释能力达65.2%，其中以交换性钙的变量投影重要性值（VIP，Variable Importance Plot）最大；这8项指标对土壤pH值表现为正效应，土壤pH值与交换性钙、全磷、全氮、有机质、碱解氮、阳离子交换量等符合线性加平台模型，与土壤粉砂粒（0.02~0.002 mm）符合线性模型。 

Preliminary study on spatial distribution and influencing factors of tobacco-growing soil pH in Chenzhou

To better understand the status of tobacco-growing soil pH in Chenzhou, 1055 soil samples were collected in 2015, and the spatial variability of soil pH and its influencing factors were analyzed by multivariate statistics and geostatistics. Results showed that the average pH value of tobacco planting soil in Chenzhou was 7.00, ranging from 4.47 to 8.14; 10.91% of tobacco planting soil had pH less than 5.5, 62.37% of tobacco planting soil had pH greater than 7; the mean pH value of tobacco planting soil in each county ranged from 5.58 to 7.26.. Results of geostatistical analysis showed that the spatial structure of soil pH followed an exponential model, and the spatial variability was mainly determined by human factors. The spatial distribution of soil pH was high in southwest and low in Northeast. Partial least squares regression analysis showed that exchangeable calcium, silt, total phosphorus, total nitrogen, organic matter, alkali hydrolyzed nitrogen, cation potassium exchange capacity (CEC) and exchangeable magnesium were the main factors affecting the pH of tobaccogrowing soil. The accumulative explanatory ability of the eight indicators to the pH of tobacco-growing soil reached 65.2%, among which the VIP (Variable Importance Plot) value of exchangeable calcium was the largest. Soil pH vs. exchangeable calcium, total phosphorus, total nitrogen, organic matter, alkali-hydrolyzed nitrogen, cation potassium exchange capacity were in line with the linear plus platform model; while that vs. silt grains (0.02-0.002 mm) followed the linear model. The results of this study provide a theoretical reference for the improvement of acid tobacco planting soil, and is conducive to the sustainable use of tobacco planting soil in Chenzhou.