重庆市潜育水稻土发育特性和系统分类研究

以重庆市境内7个发生分类的潜育水稻土典型剖面作为研究对象,通过剖面形态特征观测和理化性质测定分析,探讨其发育特性和在中国土壤系统分类(CST)中的归属。结果表明,7个供试剖面主要位于丘陵山地下坡、坡麓以及江河沿岸一级阶地,质地多为粉壤土或粉质黏壤土,不同土壤剖面中游离铁分布有较大差异,潜育特征受到人为滞水和地下水的影响,主要出现在耕作表层和受地下水位影响的深度范围内。依据CST,7个典型剖面均具有水耕表层、人为滞水土壤水分状况、潜育特征和氧化还原特征,但1个剖面虽有水耕表层但无水耕氧化还原层而隶属潜育土土纲中的石灰简育正常潜育土亚类;其余6个剖面具有水耕表层和水耕氧化还原层而分别隶属于水耕人为土亚纲中的复钙潜育水耕人为土、铁聚潜育水耕人为土和普通潜育水耕人为土亚类,依据土族和土系划分标准,建立了5个土族和7个土系。值得注意的是,目前CST中简育正常潜育土尚没有反映人为水耕活动影响(即水耕现象)的亚类,因此可以考虑新增水耕简育正常潜育土亚类。

Genetic Characteristics and Soil Taxonomy of sGleyic Paddy Soils in Chongqing

Seven profiles of typical gleyic paddy soils in Chongqing were selected as study objects, their morphological characters were observed in the field and physiochemical properties were measured in the lab. The genetic characteristics were discussed and the taxonomy were determined according to Chinese Soil Taxonomy (CST). The results showed that the tested soil profiles are mainly located in the hilly slopes or foots and the first terraces along the rivers. The textures are mostly silt loam or silty clay. The free iron is jointly affected by the formation process and parent materials, and are obviously different in profile distribution of the tested soil profiles. The gleyic features are doubly affected by artificial stagnant water and groundwater, mainly occur in the depth range of the plough layer and are affected by the groundwater level. According to CST, all tested soil profiles have anthrostagnic epipedon, anthrostagnic moisture regime, gleyic features and redoxic features, one tested profile has no hydragric horizon and is sorted into Calcaric Hapli-Orthic Gleyosols, the other tested profiles have hydragric horizon and are sorted into Recalcaric Gleyi-Stagnic Anthrosols, Fe-accumulic Gleyi-Stagnic Anthrosols and Typic Gleyi-Stagnic Anthrosols, respectively. According to the establishing standards of soil family and series, the 7 tested soil profiles were sorted into 5 soil families and 7 soil series. It is worth noting that paddy soil may have anthrostagnic epipedon, gleyic features but no hydragric horizon and only can be sorted into Hapli-Orthic Gleyosol, but no current soil subgroup in this soil group could reflect the characteristic of hydroponic cultivation, thus, the new subgroup of Anthrostagnic Hapli-Orthic Gleyosol is proposed to be added into the group of Hapli-Orthic Gleyosol in CST.