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从水稻土的抗切强度,压缩性,收缩性与水分含量的关系作了初步研究和讨论。水稻土的抗切强度随着湿度的降低而增高,塑性下限以下增加更为强烈,不存在一般所谓湿度稍低于塑性下限有一抗机械强度较小的酥软结持阶段。土壤(原状土)的压缩性以湿度大时为最高,随着湿度的降低而变小,接近塑性范围的中部,有一明显的转折点,在这转折点以下(或塑性范围的下部),土壤实际的压缩性是较小的。与旱地土壤的变化规律不一致。原因是水稻土垒结状况和粘结的条件不同。质地轻的土壤比粘重的土壤压缩性大,其压缩性降低至较小程度需要降低的土壤湿度比粘重的土壤为多,但其收缩变紧的程度不强烈,粘重水稻土在湿度降低时发生强烈收缩,使土壤变紧;当土壤湿度在塑性以下时,收缩引起土壤紧实的程度比一般人为的机械压力还更大,只有当湿度较大时,才有较高的总孔隙度。根据这些特性,提出水稻土秋耕适宜的土壤湿度是:以塑性下限为底限,以塑性中部为上限,对质地较轻的土壤,上下限宜酌量降低,但其上限不一定在塑性以下。适宜春耕的湿度比秋耕可大一些,因为晒垡和水中耕作,可再疏散土壤。
The relationship between shear strength, compressibility, shrinkage and water content of paddy soil was preliminarily studied and discussed. The shear strength of paddy soil increases with the decrease of humidity, the plasticity below the lower limit increases more strongly, there is no common so-called humidity is slightly lower than the lower limit of the plasticity of a mechanical strength of the lower soft-knot stage. The compressibility of soil (undisturbed soil) is highest at high humidity, decreases as humidity decreases, and near the middle of the plastic extent there is a clear turning point below (below the turning point) the actual soil Compressibility is smaller. And the variation of dryland soil is inconsistent. The reason is that paddy soil barrier junction condition and bonding conditions are different. Soil with light texture is more compressive than clay, with less compressibility Reduced Soil Moisture More soil than sticky soil, but less intensively tightened, viscous Paddy Soil Moisture When the soil moisture is under plasticity, the shrinkage causes soil compaction to be even greater than that of man-made mechanical pressure, and only when the humidity is large, there is a higher total porosity degree. According to these characteristics, it is proposed that suitable soil moisture for autumn soil fertility of paddy soil is as follows: the lower limit of plasticity is the limit, the upper limit of plasticity is the upper limit, and the lower limit of soil is less, but the upper limit is not necessarily below the plasticity. Suitable for spring plowing than the autumn can be larger, because sun drying and water farming, can evacuate the soil.