土壤中有效硼含量测定方法优化与对比

为确保第三次全国土壤普查数据真实可靠，需对相关标准检测方法进行反复验证以优选出适合在全国范围内推广的方法。目前NY/T 1121.8-2006甲亚胺-H比色法测定土壤有效硼灵敏度较低，显色温度及光照等因素容易对测定结果造成干扰。鉴于此，本文对沸水浴浸提-甲亚胺-H比色法测定土壤有效硼过程中的浸提时间、浸提方式以及显色条件等关键因素进行了分析，并探究方法测定优化条件。结果表明提取时间选择12 min、加盖浸提以及23 ℃避光显色处理，可以较好地减少有效硼测定过程中的误差，获得更为准确的结果。同时对电感耦合等离子体光谱法（ICP-OES）测定土壤有效硼进行了验证，比色法、ICP-OES法的检出限分别为0.012 mg/kg、0.009 mg/kg，均满足分析测定的要求。方法准确度和精密度验证结果表明二者均可用于土壤有效硼的测定，并且实际样品测定结果无显著性差异。其中，比色法适用于测定高含量（>0.5 mg/kg）样品，ICP-OES法适用于中、低含量样品的测定。结合第三次全国土壤普查内业检测定点工作中的经验，本文建议将ICP-OES法作为第三次全国土壤普查有效硼测定的首选方法，以期为“三普”内业检测提供参考和借鉴。

Optimization and comparison of the detection methods for soil available boron content

In order to ensure the authenticity and reliability of The 3rd National Soil Survey data, the standard detection methods need to be repeatedly verified to optimize the method suitable for nationwide promotion. At present, the sensitivity of NY/T 1121.8-2006 methylimine-H colorimetric to test available boron in soil is low, and factors such as color rendering temperature and light are easy to interfere with the test results. In view of this, this paper analyzed the key factors such as leaching time, leaching method and color rendering conditions in the process of detection of soil available boron by boiling water bath leaching-methylenimine-H colorimetric, and explored the optimal conditions for the detection of the method. The results showed that the leaching time of 12 min, capping leaching and 23 °C dark environment in color rendering process could better reduce the error in the detection of available boron and obtained more accurate results. At the same time, the detection of soil available boron by inductively coupled plasma spectroscopy (ICP-OES) was verified. The detection limits of colorimetric and ICP-OES were 0.012 mg/kg and 0.009 mg/kg, respectively, which met the requirements of analysis and testing. The accuracy and precision verification results showed that both methods could be used for the detection of soil available boron, and there was no significant difference in the test results of actual samples. Among them, the colorimetric method was suitable for the determination of high content (>0.5 mg/kg) samples, and the ICP-OES method was suitable for the detection of medium and low content samples. Combined with the experience in detection of 3rd National Soil Survey pilot work, it was suggested that ICP-OES should be as the standard method for the detection of soil available boron, which is in order to provide reference for the 3rd National Soil Survey.