四川盆地近40年降雨量对耕层土壤pH时空变化的影响

Influence of 40-year precipitation on temporal and spatial variation of arable soil pH in the Sichuan Basin

【目的】耕层土壤酸化问题制约着农作物生产安全,本研究从降雨淋溶造成耕层土壤pH变化的角度出发,探讨长时间降雨量影响着耕层土壤酸化的时空变化趋势,为耕层土壤酸化治理提供科学依据。【方法】以四川盆地紫色土和水稻土耕作层土壤(0~20 cm)为研究对象,利用1980年二次土壤普查数据为基础,结合近期耕层土壤调查数据和四川盆地降雨量数据,应用地统计学方法分析40年来四川盆地耕层土壤pH变化趋势和降雨量分布,采用方差分析和回归分析探讨降雨量对耕层土壤pH时空变化的影响。【结果】地统计分析显示:空间上,1980年和2020年两时段的耕层土壤pH变异系数都在15%左右,同属中等程度空间变异。时间上,40年来四川盆地耕层土壤pH平均下降0.7,对比pH差值分布图和降雨量分布图发现pH下降幅度较大的区域与年降雨量较大区域吻合。方差和回归分析表明,四川盆地40年来降雨量对耕层土壤酸化有显著影响(P<0.05),当不同市域年平均降雨量相差超过100 mm时,pH差异显著(P<0.05)。40年来降雨量对耕层土壤酸化时空独立解释能力可达41%。【结论】四川盆地40年降雨量大小影响着耕层土壤酸化的时空进程,因此应长期关注极端降雨事件,为治理土壤酸化做好必要的防范准备。

【Objective】The problem of soil acidification in the arable layer is constraining the safety of crop production. The present study aims to explore the spatiotemporal variation of soil acidification in the arable layer influenced by long-term rainfall, from the perspective of pH changes caused by rainwater leaching. The objective is to provide a scientific basis for the management of soil acidification in the arable layer by investigating the long-term trends of rainfall impact on soil acidification in the arable layer. 【Method】 The arable layer(0-20 cm) of purplish soil and paddy soil in the Sichuan Basin were taken as research objects, based on the second soil census in 1980, along with recent surveys and precipitation statistics in the Sichuan Basin, the pH variation of topsoil and precipitation distribution in the Sichuan Basin over the past 40 years were geostatistically analyzed to discuss the influence of precipitation on the temporal and spatial changes of pH of arable layer using ANOVA and regression analysis. 【Result】 The geostatistical analysis showed that spatially, the coefficient of variation of topsoil pH was around 15% in both 1980 and 2020, indicating that both were moderate spatial variation;Temporally, the topsoil pH decreased by 0.7 on average in the Sichuan Basin over 40 years. With comparison of pH difference distribution and precipitation distribution, the area with higher pH reduction overlapped the area with higher annual precipitation. The ANOVA and regression analysis showed that precipitation in the Sichuan Basin over 40 years had a significant influence on the acidification of topsoil(P0.05). As the difference in annual average precipitation between different municipalities exceeded 100 mm(P0.05), there was a significant difference in the pH(P0.05). The influence of 40-year precipitation accounted for 41% on the spatial-temporal variation of topsoil acidification. 【Conclusion】 The precipitation in the Sichuan Basin over 40 years affects the spatial-temporal processes of topsoil acidification, to address this problem, extreme precipitation events are long-running concerns that require necessary preventive measures for governance of soil acidification.