Abstract
Soil moisture was estimated by the tensiometric method of analyzing the soil moisture status of a pine forest. The examined pine forest (Pinus densiflora SIEB. et SUCC.) was the experimental area for increasing the mushroom (Tricholoma Matsutake ITO et IMAI (SING.)) production sprinkling water was supplied to a part of the forest
during the non-rainfall period of this examination. The authors tested correlations between the soil moisture status and the weather conditions, e. g. rainfall, and temperature of soil and atmosphere in the same stand. They investigated the relationship between variation of soil moisture by the sprinkling water and some physical properties of the soils.
The results are summarized as follows: 1. The soils of the forest belong to the dry brown forest soil (BA type). 2. The soil moisture status (pF value) in the forest varied according to the rainfall. The pF value increased to high potential (maximum value was pF 2.89) in the non-rainfall period, and it decreased to low potential (minimum value was pF 1.30) shortly after rainfall. The pF value for the long term was influenced by the rainfall conditions (amount of precipitation, frequency, duration, etc.). The frequency of rainfall was a fairly important factor among them. 3. Sometimes lower horizons kept higher range of the pF value than upper horizons in the same profile. It was considered that the interruption of water percolation occurred due to the water-proofing property of the dry soil, and that the coarse pore of equivalent to less than pF 2.7 has also the water-proofing property. 4. The continuous sprinkling water supply of 20mm a day affected the soil moisture status of 30cm depth surface soil
