Soil consists of inorganic materials such as sand and clay, organic matter derived from living organisms, small animals like millipedes and earthworms, microorganisms such as fungi and bacteria, water, and air. In this diverse and dynamic environment, we explore various phenomena and the characteristics of substances within the soil from the perspectives of soil physics, soil chemistry, and colloid science.

1. Water, Solute, Gas, and Heat Transport Properties in Soil
   Within soil, water, solutes, gases, and heat move under a variety of influences. We investigate the behavior of these substances and thermal processes in soil. Numerical simulations are also used to predict material and heat dynamics within the soil.

2. Dynamics of Colloidal Materials in Soil
   Soil contains fine particles (colloidal materials) ranging from the nano- to the microscale. Highly reactive colloids can also act as carriers for pollutants. We study the behavior of colloidal materials within soil environments.

3. Heterogeneity of Physicochemical Properties in Agricultural Soils
   In agricultural fields, spatial variability in soil physicochemical properties leads to uneven crop growth. To efficiently apply fertilizers and soil amendments, it is necessary to clarify such heterogeneity in soils.

4. Adsorption Phenomena and Soil Dispersion in Soil Systems
   We explore the mechanisms of substance adsorption onto soil surfaces and the phenomena of soil dispersion and aggregation. Various forces—such as electrostatic interactions, van der Waals forces, and hydrophobic interactions—act within soil environments.

5. Visualization and Quantification of Internal (Pore) Structure in Soil
   The movement of substances in soil occurs through its internal pore spaces. Using tools such as X-ray CT scanners, we visualize the internal pore structure of soils and investigate its relationship with material transport.