基于综合等级划分方法的土地质量地球化学评价——以吉林省乌拉街镇为例

采用图斑+网格化布样以及"S"型采样方法，采集表层土壤、灌溉水、大气干湿沉降物、农作物等样品677件，依据综合等级划分方法对吉林省乌拉街镇一带开展了土地质量地球化学评价，评价面积为153 km²。结果表明：评价区土地质量地球化学综合等级一等的约占全区面积的49.32%，二等占21.94%，三等占28.38%；该区玉米中重金属元素Cr，Cu，Zn，As，Cd，Hg，Pb质量分数分别为<0.87，0.91~2.60，15~27，<0.050，0.003~0.018，<0.010，<0.050 mg/kg，均符合国家标准；土壤酸碱度变化范围为4.43~8.09，平均值5.48，土壤酸化问题严重，酸性土壤占全区的78%，强酸性土壤占15%。该区综合土地质量为优良水平，对农作物种植较为适宜；但是，土壤酸化以及硼缺乏（0.35 mg/kg，处于4级水平0.2~0.5 mg/kg）问题应引起足够重视，亟待采取有效措施加以防治。

Geochemical Assessment of Land Quality Based on Comprehensive Grading Method: A Case Study of Wulajie Town in Jilin Province

Using patches + grid pattern and "S" sampling method, a total of 677 samples were collected from surface soil, irrigation water, atmospheric dry-wet deposition, and crops and root soil. By comprehensive grading method, the authors carried out a land quality geochemical evaluation in Wulajie Town of Jilin Province. The evaluation area is 153 km². Based on the comprehensive geochemical grade, the first grade land accounts for 49.32% of the total area, the second grade land for 21.94%, and the third grade land for 28.38%.The contents of heavy metals of Cr, Cu, Zn, As, Cd, Hg, and Pb in the corn in the evaluation area were <0.87,0.91-2.60,15-27,<0.050,0.003-0.018,<0.010,and <0.050 mg/kg,respectively, which were in accordance with the national standards. The variation of soil pH value was 4.43-8.09 with an average of 5.48, and soil acidification was serious. The acidic soil accounts for 78% of the total area, the strong acidic soil accounts for 15%. The comprehensive land quality of this area is at a good level and suitable for planting crops. However, acidification and boron deficiency (0.35 mg/kg) is at 4th level (0.2-0.5 mg/kg), and effective control measures should be taken.