The distribution of226Ra and238U in various soils has been studied. Supposing that radioactive equilibrium were in existence, the average activities of226Ra and238U would show a nearly 11 correlation. As weathering affects radioactive equilibrium in surface soil, radioactive equilibrium was not in existence. Therefore, four kinds of soil were selected from different weathering conditions, viz. river bed soil, paddy field soil, field soil and uncropped soil. The226Ra/238U ratio of various soils lies in the range of 1.63 to 2.41. The activity concentrations of226Ra were greater than238U in various soils. The ratio226Ra/238U can be shown to be a quantitative index of weathering. Phosphatic manure contains238U and its daughter isotopes in concentrations far exceeding the average abundance in the earth's crust. But the cultivated soils (paddy field soil, field soil) are not affected by fertilizers in Kamisaibara.