Physical Fertility of Soils and the Drainage Efficiencies of Upland Field

Abstract

Alluvial soil in Fukaya, locating at a basin of Tone River in Saitama prefecture, has been perceived to be a ‘good’ soil. Recently, however, some fields in this area were damaged and the drainage efficiency is being degraded. The objective of this study is to investigate and evaluate the physical fertility of the field in the viewpoint of the drainage efficiency and the physical and chemical properties of the soil including the aggregate stability.
The pattern of hardness profile and the dispersion of the hydraulic conductivity in each field, and the stability of aggregates influence the drainage efficiency. The combination of these factors and other physical and chemical properties of soils also affected the drainage efficiency. Physically fertile fields were classified into two types; the first, all the properties of the soil have advantage for good drainage and, secondly, the favorable properties of soils compensated the unfavorable properties of them. On the other hand, soils in physically unfertile fields were either possessing worse properties or exceeding the unfavorable properties to their favorable properties. The balance of each physical property of soils, as well as their spatial heterogeneity, was crucial to keep them physically fertile.