土地质量地球化学评价成果与若干问题探讨:以浙江省金华市汤溪镇为例

Land Quality Geochemistry Evaluation and Discussion on Some Issues:A Case in Tangxi Town,Jinhua City,Zhejiang Province

为进一步总结完善丘陵盆地区中大比例尺土地质量地球化学调查评价方法技术,2013年在中国地质调查局的支持下,选择浙江省金华市汤溪镇农用地分布区开展了试点调查和采样密度对比试验。基于调查数据进行了土壤酸碱度(p H)、土壤养分丰缺、土壤环境质量和土壤质量地球化学综合评价与分级,探讨了丘陵盆地区野外采样密度。结果表明:区内土壤p H值低、酸性土壤广泛分布;土壤养分元素氮、磷、钾普遍缺乏;土壤环境质量总体较好,仅局部地区出现重金属元素超标;土壤质量地球化学综合等级以一等、二等为主,优良土地面积占调查区的92. 6%,土壤酸性强、养分缺乏是影响调查区土地质量的主要原因,建议采取适当措施调控土壤酸碱度、补充土壤养分;丘陵盆地区中大比例尺土地质量地球化学调查应适当提高土壤采样密度,有效控制土地利用图斑,以便于调查成果在土地资源管护中的应用。

In order to summarize and improve the methods of middle to large-scale land quality geochemical survey and evaluation,a pilot survey organized by the China Geological Survey was conducted in 2013 in Tangxi Town,Jinhua City,Zhejiang Province,a typical hilly-basin area at south China.Agricultural land was the main object of survey,and a sampling density test was conducted covering an area with several types of land-use.The survey area is approximately 90 square kilometers,and the sampling density varies from 9 to 16 points per square kilometer.Soil pH,soil environment quality,nutrient level,and soil quality were evaluated and graded based on elemental concentrations.The results indicate that soil pH is relatively low and about 90%of the survey area is acid-stage soil;nutrient elements in soils are not abundant,about 40%of the area is lack of nitrogen and potassium,73%lack of phosphorus;soil environment quality is good and about 92.6%of the land is of high quality grade.Soil acidification and infertility are the main problems for the survey area.Therefore,it is urgent to take measures to neutralize acid soil and replenish fertilization.The sampling density should be increased so that the survey data can be directly used for land resource management at hilly-basin areas.