摘要:以陕西省耕层土壤为研究对象，利用1980s第2次土壤普查数据和2017年的705个样点分析数据，基于地统计学和ArcGIS分析耕层土壤pH时空变化特征，并采用相关分析和方差分析方法探讨其影响因素，对于陕西农业可持续发展及生态环境保护具有极其重要的意义。结果表明，陕北、关中及陕南地区耕层土壤pH均值依次为8.25、7.91、6.25，分别为弱碱性、弱碱性和弱酸性；各行政区耕层土壤pH排列顺序为延安>榆林>铜川>咸阳>渭南>西安>宝鸡>商洛>安康>汉中。时间上，与1980s相比，陕北和关中耕层土壤呈碱化趋势，陕南耕层土壤呈酸化趋势；各行政区除榆林、安康、汉中和商洛耕层土壤呈酸化趋势，其余各市耕层土壤均呈碱化趋势。空间上，陕北和陕南耕层土壤pH拟合的最优半方差函数模型为线性模型，关中耕层土壤pH拟合的最优半方差函数模型为高斯模型，均表现出较强的空间相关性。陕北耕层土壤pH空间分布呈零星斑状特征，关中和陕南耕层土壤pH空间分布呈东部高于西部特征。坡向、海拔与陕西省耕层土壤pH显著相关，坡度越小，海拔越高，pH越大，不同类型的土壤pH存在差异。建议陕北和关中地区防治土壤盐碱化问题，陕南地区防治土壤酸化问题，以促进农业可持续发展和保障区域粮食安全。
关键词:陕西省/
耕层土壤pH/
空间相关性/
地形/
土壤类型
Abstract:Rapid development of the economy has increased the occurrence of declining cultivated land quality, such as acidification and salinization in China. To provide a scientific basis for adjustment of topsoil pH and to realize the rational use of land resources in Shaanxi Province, this study examined pH of 705 topsoil samples from Shaanxi Province using a soil/water ratio of 2.5/1 in 2017 and incorporated soil pH data from the second national soil survey in 1980s. The spatio-temporal changes and classification characteristics were analyzed via ArcGIS, and the influencing factors were investigated by correlation analysis and analysis of variance methods. General statistical analysis and normality tests were performed in Excel 2016 and SPSS 22.0; and the GS+9.0 software was adopted to obtain the best fitting model. The ordinary Kriging method was used for spatial interpolation analysis and mapping. The study is important for sustainable agriculture development and ecological environment protection in Shaanxi Province. The results showed that pH values of farmland soil in northern Shaanxi, Guanzhong, and southern Shaanxi were 8.25, 7.91, and 6.25, respectively, and the corresponding levels were 5 (alkalescence), 5 (alkalescence), and 3 (weak acidity), respectively. The order of soil pH in the administrative regions was Yan'an > Yulin > Tongchua > Xianyang > Weinan > Xi'an > Baoji > Shangluo > Ankang > Hanzhong. The topsoil pH in Hanzhong City showed moderate variation, whereas the other cities in Shaanxi Province showed weak variation. Compared with the 1980s, the farmland soil in northern Shaanxi and Guanzhong showed an alkalization trend, whereas the surface soil in southern Shaanxi showed an acidification trend. In the administrative regions, the topsoil in Yulin, Ankang, Hanzhong, and Shangluo showed an acidification trend, and the soil in other cities showed an alkalization trend. The optimal fitting semi-variance function model of farmland soil pH in northern and southern Shaanxi was a linear model, and the optimal fitting semi-variance function model of farmland soil pH in Guanzhong was a Gaussian model; both showed strong spatial correlation. Furthermore, the topsoil pH in northern Shaanxi was primarily influenced by structural factors, whereas the topsoil pH in Guanzhong and southern Shaanxi was influenced by structural and random factors. The spatial distribution characteristics of topsoil pH were sporadic in northern Shaanxi, and that in Guanzhong and southern Shaanxi was higher in the east than in the west. Changes in soil pH were affected by natural and human factors, such as topography, soil type, climate, and fertilization. Slope and elevation were significantly (P < 0.05) correlated with topsoil pH in Shaanxi Province; lower slopes and higher altitudes had higher soil pH. To promote sustainable agriculture development and regional food security, soil salinization should be prevented in northern Shaanxi and Guanzhong and acidification should be prevented in southern Shaanxi.
Key words:Shaanxi Province/
Topsoil pH/
Spatial correlation/
Topography/
Soil type
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