本文以河南省泌阳暴雨中心区为例 ,在野外土壤调查和室内理化分析的基础上 ,分析讨论了暴雨对土壤组成和性质的影响。结果表明 ,暴雨中心区土壤因长期的暴雨冲刷 ,土层浅薄 ,发生层数目少 ,土体构型简单 ;砾石含量高 ,物理性粘粒含量低 ,质地类型多属多砾质砂土 ;土体中不出现肉眼可辨的铁锰结核 ;土壤淋溶作用强烈 ,呈微酸性反应 ;土壤有机质和速效氮含量较高 ,而速效钾含量偏低 ,有机质表聚化现象不明显 ;盐基淋溶率小于 1 0 0 ,土体SiO2 /R2 O3小于 7 0 0 ,脱硅和富铁铝化作用明显 ,土体风化程度较高。对暴雨中心区附近的土壤来说 ,上述土壤组成和性质均出现明显的差异。

Climate is a basic factor that controls the directions and intensities of soil-forming process, which affects the levels of weathering, the composition and decomposition of soil organic matter (SOM), the migration of soil materials and changes of their forms,and soil geographic distribution around the world and so on. Although many scholars have done a lot of work about the influence of precipitation on components and properties of regional soils, yet the main concern of their work is average precipitation or the moist indexes influencing soil individual component and properties, and the influence of rainstorm on components and properties of regional soils has not been discussed thoroughly yet. Taking the central area of rainstorm in Biyang county as an example, the influence of rainstorm on soil components and properties was discussed on the basis of field works and laboratory experiments in this paper. In comparison with the soils of other areas that are less affected by rainstorm, the soils in the central area of rainstorm in Biyang have the following characteristics: (1) Eluviation ratios of base (β) are less than 1.00, silica-sesquioxide ratios (Saf) are less than 7.00, and the soil reaction is feeble acid in the central area of rainstorm, which indicate that the processes of desilicification and allitization in soils are obvious, and that the weathering of soil is stronger. (2) Soil thickness is thinner.The amount of horizons in each soil is less, no more than two, and the patterns of soils profiles are simple. Content of gravels (>1 mm) is higher, and that of physical clay (<0.01mm) is lower. The texture of soil belongs to sandy type, most of them have some gravel. (3) Iron-manganese nodules that could be seen by unaided eye could not be found in all soils located, which indicates that soil-forming conditions are unstable in this area. (4) The content of soil organic matter (SOM) and alkali-hydrolyzable nitrogen is higher, and readily available potassium is lower in the central area of rainstorm. Because much soil organic matter (SOM) migrated from up to down, the content of soil organic matter in second soil horizon is higher too. Soils around the central area of rainstorm have different components and properties from these in the central area of rainstorm obviously, which indicates that rainstorm can influence components and properties of soils strongly.