Effects of the Surface Tension on Horizontal Infiltration.

A plant growth system for crop production under microgravity is part of a life supporting system designed for long-term space missions. In space, plant growth in soil culture requires the understanding of water movement in soil under microgravity. Under microgravity, it is forecasted that water moves from high to low matric potential locations. However, previous studies showed matric potential did not change whether volumetric water content was high or low under microgravity. The result might be due to the change of capillary forces, which cause matric potential in porous media. The objective of this study is to evaluate the effects of the changes in capillary forces on horizontal infiltration. This study revealed low capillary forces slow water movement and make water distribution ununiformed.