基于粒度对比法的坝上农田风蚀与粉尘释放量估算

为了计算当前年内的农田风蚀量，该研究利用农田耕作层土壤粒度组成较均一，风蚀使表层可蚀性颗粒减少，不可蚀颗粒含量相对增加这一特点，通过比较一个风蚀季结束后，农田耕作层表层与下层可蚀性颗粒与不可蚀颗粒相对含量的变化，提出了一种估算当前年内土壤风蚀量和粉尘释放量的方法，并给出了风蚀量与粉尘释放量的计算公式。利用此方法对河北坝上地区主要农田类型土壤风蚀量和粉尘释放量进行计算。计算结果表明，2013年研究区农田风蚀量为960～5700 g/(m2·a)，平均为2852.14 g/(m2·a)，平均风蚀深度为0.21 cm/a，从强度上划分属于重度风蚀。农田平均粉尘释放量为768.16 g/(m2·a)，约占农田平均风蚀量的29.00%。粉尘释放量与风蚀量之间有显著的线性相关关系，翻耕耙平地的风蚀量和粉尘释放量显著大于留茬地。该方法的估算结果与前人采用其他方法得到的结果以及实地观测得到的结果基本吻合。

Estimation on farmland wind-erosion and dust emission amount in Bashang of Hebei province by grain composition contrast

Abstract: There are many ways to estimate soil wind-erosion, but no way can accurately estimate the wind erosion amount in the current year. In this study, taking advantage of the feature in the plow layer of farmland that the size composition is uniform, and the erodible particles decreasing and non-erodible particles increasing relatively by erosion in soil surface, we proposed a new method of estimating soil erosion and dust emission amount by comparing the relative change in the content of non-erodible and erodible particles between the surface and lower layers after a wind-erosion season, and giving the calculating formulas. There are four assumptions in this method: (1) there are both erodible and non-erodible particles in the plow layer of farmland. (2) The soil size composition in the plow layer is uniform, and its vertical variation can be negligible before a wind erosion season begins. (3)The farmland wind-erosion occurs from the crop harvesting of last year to the crop planting of the next year. (4) Other factors that cause changes in the size composition of surface soil can be negligible except for wind-erosion. The four assumptions are established for long plowed farmland located in arid or semi-arid regions.The size range of non-erodible particles was identified as > 1.0mm in this study. The soil erosion and dust emission amount of the main farmland types in Bashang of Hebei province in the current year was estimated by this method. The results showed that the farmland wind-erosion amount in 2013 was 960~5700 g/(m2·a), with an average of 2852.14 g/(m2·a), and the average erosion depth was 0.21 cm/a, which amounted to severe wind erosion. The average dust emission amount was 768.16 g/(m2·a), and accounted for about 29.00% of the average wind-erosion amount. There was a significant linear correlation between the dust emission and wind erosion, and the correlation coefficient(r) was 0.95. The wind-erosion and dust emission amount for different sample points were different and that was related closely to the desertification degree of the farmland. The wind erosion and dust emission amount in plowed and raked land was significantly greater than in the stubble's. The results of the farmland erosion amount obtained by this method were basically consistent with previous results obtained by other methods and our observation results indicated that this method had good feasibility. This method is simple, convenient and quick to operate, doesn't need to consider a variety of wind-erosion factors, and doesn't require long field observation. It has application in the evaluation of soil erosion, the desertification evolution of farmland, soil dust emission, sand disaster prevention, and so on.