Studying how rocks in soil affect water movement is important. Researchers tested how stones in soil change how water moves through it. They made mixtures of soil and different amounts of stones, then measured how well water moved through them. They found that more stones in the soil make it harder for water to move through. Simple models worked well for soils with a little bit of stones, but not for soils with a lot of stones. Stones in soil make the spaces where water can move wider.