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本文提出绘制养分等值图的方法,可以直观地描述养分在土壤中的分布状况。养分等值图表明土壤有机质的分布是不均匀的,速效磷的波动则更大。同时作者还提出将分析误差的若干倍作为允许误差与均值的标准差(Sx)作为采样误差,从而导出采样误差与分析误差的关系模式S=τA,(τ为参量等于m/t)和采样点数N的模式N=t~2S~2/(mA)~2(N为采样点数,t为要求概率下的置信水平,S为标准差,A为分析误差,m为允许误差的系数。)本文利用此公式制成了有机质和速效磷能达到要求精度的最低采样点数,可直接查取。正确采集土壤农化样本的关键在于根据要求提出合理可行的精度标准,然后确定足够的采样点数。样点要分布均匀,采样方式和精度并无密切的关系。
This paper presents a method of drawing nutrient equivalence map, which can describe the distribution of nutrients in soil intuitively. The nutrient equivalence map shows that the distribution of soil organic matter is not uniform and that of available phosphorus is even greater. At the same time, the author also proposed to use several times of analysis error as the standard deviation (Sx) of allowable error and mean value as sampling error to derive the relationship between sampling error and analysis error, S = τA, (τ is the parameter equal to m / t) N is the number of sampling points, t is the confidence level at the required probability, S is the standard deviation, A is the analysis error, and m is the error-tolerant coefficient. This formula uses this formula made of organic matter and available phosphorus to achieve the required accuracy of the minimum sampling points, can be directly retrieved. The key to correctly collecting soil samples is to put forward reasonable and feasible accuracy standards according to requirements and then to determine enough sampling points. Samples should be evenly distributed, sampling methods and accuracy are not closely related.