中文摘要：

耕地质量监测是及时掌握耕地质量和产能变化的必要手段,科学合理的抽样方法不仅能保证监测精度,还可以减少监测成本。本文以河北省黄骅市为研究区域,结合区域耕地质量的实际状况,运用6种抽样方法抽取耕地单元作为监测样点,并计算和比较不同抽样均值的最大相对误差和相对抽样精度。结果表明,抽样精度随着样本容量的增加而提升,速度由快变慢。与简单随机抽样相比,在抽样精度方面,系统分层抽样和系统等距抽样的优势极大,并随着样本数量的增加优势扩大;等别分层抽样的优势较大并且平稳;乡镇分层抽样的优势不大。网格分层抽样不但没有优势,反而可能造成精度的损失。不同的抽样方法在满足相同的监测精度时所需的样本量差异显著,合理的抽样方法在满足监测精度的同时,可以明显地减少样本量。本研究有助于选择出最合适的抽样方法,以期为耕地质量监测中不同抽样方法的精度比较提供方法指导。

英文摘要：

Cultivated land monitoring is an essential way to obtain information about the change in land quality and productivity in time. A scientific and rational sampling method can ensure monitoring precision and reduce monitoring costs. We took Huanghua in Hebei as the study area, illustrated the implementation steps of different sampling methods in detail; drew samples in different sampling methods based on cultivated land quality condition; listed the formulas of sample variance and maximum relative error of the sampling mean; calculated and compared the maximum relative error of the sampling mean and the relative sampling precision of different sampling methods. Our results show that sampling precision increases from fast to slowly when the sample size increases. In the matter of sampling precision, compared with the simple random sampling, system stratification sampling and system isometric sampling have overwhelming advantages which increase obviously when the sample size increases. The grade stratification sampling has a little greater advantage which changes smoothly when the sample size increases. The town stratification sampling has a razor-thin advantage, but the grid stratification sampling does not have any advantage, instead, it may cause precision loss. When sampling precision is the same, the sample sizes of different sampling methods are significantly different, so on the condition that different sampling methods achieve the same sampling precision, a reasonable one can obviously reduce sample size and save monitoring costs. This study aims to provide effective methodological guidance for the precision estimation and comparison of different sampling methods, which helps to select the most reasonable sampling method in cultivated land monitoring.