压砂地土壤盐分空间变异规律

目的]研究不同种植年限压砂地及裸地不同土层土壤盐分的空间变异特征,为西北干旱地区土壤盐渍化改良和利用提供理论依据。方法]以甘肃省景泰县压砂地及裸地不同土层土壤盐分数据为基础,运用经典统计学和地统计学相结合的方法,分析土壤盐分统计特征值,半方差模拟模型及其拟合参数和等值线分布图。结果]压砂地土壤盐分均值明显低于裸地,且裸地老砂地新砂地中砂地,裸地与压砂地各层土壤盐分的均值差异较大,且土层Ⅳ(30—50cm)土层Ⅲ(20—30cm)土层Ⅱ(10—20cm)土层Ⅰ(0—10cm);裸地Ⅱ,Ⅲ,Ⅳ层,中砂地各层土壤盐分属于弱变异性,其他各地型各土层土壤盐分都属于中等变异性。裸地Ⅰ,Ⅲ层,新砂地第Ⅲ层,中砂地第Ⅰ层,老砂地Ⅰ,Ⅱ,Ⅲ层土壤盐分半方差函数最佳理论模型为指数模型,裸地第Ⅱ层为线性模型,其他各地型各土层均为球状模型。裸地第Ⅱ层土壤盐分具有弱空间相关性,其余各土层土壤盐分均具有强相关性。试验区土壤盐分北部高于南部,且各土层土壤盐分在一定范围内存在空间上的变异性和相关性。结论]土壤表层压砂能有效减小土壤盐分表聚,抑制土壤次生盐渍化,不同种植年限压砂地不同土层土壤盐分在一定范围内存在空间上的变异性和相关性。

Variation Pattern of Soil Salinity of Gravel-sand Mulched Field

Objective] We studied the variation pattern of soil salinity at different layer of GSM (gravel‐sand mulched field) and CK in order to provide basis for improvement and utilization of soil salinization in the northwest arid area in China .Methods] Based on the statistics at different layer of GSM and CK ,classical statistics and geo‐statistics were used to analyze the statistical characteristic value ,semi‐variance simulation model and its fitting parameters ,and the isocline distribution map of soil salinity in Jingtai County of Gansu Province . Results] Mean soil salinity of GSM was lower than that of CK ,and the result showed :CK > OGM (old gravel‐sand mulched field) > NGM (new gravel‐sand mulched field ) > MGM (middle gravel‐sand mulched field) .There were significant differences in soil salinity among different layers of GSM and CK ,and the result showed :layer Ⅳ (30 — 50 cm)> layer Ⅲ (20 — 30 cm) > layerⅡ(10 — 20 cm)> layerⅠ(0 — 10 cm) .The variations of soil salinity in layerⅡ ,Ⅲ ,Ⅳ (CK) and MGM were weak ,while variations in other layers were moderate .The best semi‐variance theory model of layer Ⅱ (CK) was linear model ,the optimal model for layer Ⅰ , Ⅲ (CK) ,layerⅢ (NGM ) ,layer Ⅰ (MGM ) and layer Ⅰ , Ⅱ , Ⅲ (OGM ) was exponential model ,while the best model for other layers was spherical model .The spatial auto‐correlation of soil salinity at layer Ⅱ (CK ) was lower , while it was high at other layers .The soil salinity in northern area was higher than that in southern area . Conclusion] Gravel sand on soil surface can reduce soil salt accumulation and control soil secondary salinization , and there is spatial variability and correlation exists in soil salinity among different layer of GSM and CK .