School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou, 221116, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
Environ Monit Assess. 2021 Apr 26;193(5):304. doi: 10.1007/s10661-021-09080-4.
Soil acidification has always been a substantial eco-environmental problem restricting agricultural development in the red soil region of southern China. It is necessary to determine the dynamic change in soil pH in this area to formulate regional agricultural and environmental management measures. Yujiang County, a typical county with red soil acidification in southern China, was selected as the study area. Based on soil data from 1982, 2007, and 2018, the spatiotemporal variation characteristics and the latest changes in soil pH in the county were analyzed. The results show that the soil pH in Yujiang County decreased from 5.66 to 4.74 and then increased to 4.96 from 1982 to 2018, showing a trend of first decreasing and then increasing. According to the spatial distribution characteristics of soil pH, the low soil pH values in the three periods were mainly distributed in the northern mountainous areas with more forestland and dry land area and some southern hilly areas, while the paddy soil pH values in the middle low hilly areas were relatively higher. The soil pH decreased rapidly from 1982 to 2007, showing a large area of acidification. In 2007, the proportions of acidic (4.5 < pH < 5.5) and strongly acidic (pH < 4.5) soils increased by 67.37% and 10.6%, respectively, compared with that in 1982. However, from 2007 to 2018, the soil pH of the whole county increased, and the acidification trend was alleviated, which is of great significance to the regional red soil ecological environment. Through the analysis of the main factors affecting the change in soil pH, it was found that the sharp decline in soil pH in Yujiang County during 1982-2007 was mainly caused by acid rain and excessive nitrogen application. From 2007 to 2018, no significant reduction in nitrogen fertilizer in this area occurred, and although the increase in soil organic matter contributed to alleviating soil acidification, the analysis showed that the decrease in acid rain was the main reason for the rise in soil pH in Yujiang County. At the same time, notably, there is a large area of soil in the area that is still acidic, and effective control of soil acidification is still an important ecological and environmental issue in this area. In order to further improve the pH value of soil in red soil region, it is suggested that on the basis of continuous improvement of acid rain, in addition to increasing soil organic matter by returning straw to field and other measures, appropriate amount of lime or alkaline biochar can be applied to better improve the soil ecological environment in red soil hilly region.
土壤酸化一直是制约中国南方红壤区农业发展的重大生态环境问题。有必要确定该地区土壤 pH 值的动态变化，以制定区域农业和环境管理措施。本研究选择中国南方典型酸化红壤区的余江县作为研究区。基于 1982 年、2007 年和 2018 年的土壤数据，分析了该县土壤 pH 值的时空变化特征及最新变化情况。结果表明，1982 年至 2018 年，余江县土壤 pH 值先降低后升高，从 5.66 降低至 4.74，然后增加至 4.96。根据土壤 pH 值的空间分布特征，三个时期的低土壤 pH 值主要分布在北部山区，该地区林地和旱地较多，还有一些南部丘陵地区；而中部低丘地区的稻田土壤 pH 值相对较高。土壤 pH 值从 1982 年到 2007 年迅速下降，呈现出大面积酸化的趋势。与 1982 年相比，2007 年土壤 pH 值在 4.5<pH<5.5 和 pH<4.5 的酸性和强酸性土壤比例分别增加了 67.37%和 10.6%。然而，从 2007 年到 2018 年，全县土壤 pH 值整体呈上升趋势，酸化趋势得到缓解，这对区域红壤生态环境具有重要意义。通过分析影响土壤 pH 值变化的主要因素，发现 1982-2007 年余江县土壤 pH 值急剧下降主要是由于酸雨和过量施氮。2007 年以来，该地区氮肥施用量无明显减少，虽然土壤有机质的增加有助于缓解土壤酸化，但分析表明，酸雨的减少是余江县土壤 pH 值上升的主要原因。同时，值得注意的是，该地区仍有大面积土壤呈酸性，有效控制土壤酸化仍是该地区重要的生态环境问题。为进一步提高红壤区土壤 pH 值，建议在持续改善酸雨的基础上，除了通过秸秆还田等措施增加土壤有机质外，还可以适量施用石灰或碱性生物炭，以更好地改善红壤丘陵区的土壤生态环境。
