eli5: Why does wet earth (like right after rain) absorb more water then dry earth (like right after a drought)?

Question

Title. I saw a video showing it happening, but I don’t understand why.

In: 51

Answer 1

The real reason is that water has a very high surface tension. It is hard for gravity to pull a drop of water into dry pores between soil particles. Once water DOES manage to infiltrate the pore space, it becomes easier for more water to move through. If the pore spaces are already wet, it is easier for the soil to absorb more moisture until it gets 100% saturated.

Fluids with LOW surace tension will infiltrate soil much more easily.

Viscosity is a factor here, too, but viscocity and surface tension vary together