If you have watched crops suffer through a drought or have seen yields jump after installing drainage tiles, then you understand that water is a fundamental factor for good crop yields. Like animals, plants need large amounts of water every day. Yet, too much water deprives roots of air and makes soil susceptible to compaction. Water carries soil, nutrients, and other substances, so water management is essential to controlling erosion and pollution. How these processes occur depends on soil type and management.
Infiltration is the rate at which water gets through the surface and into the soil.
With higher infiltration, more water will be available to plants and less will run off the surface, erode soil, and wash away nutrients. Crop residue, living plants, or a rough soil surface will slow down the flow of water so more can infiltrate. A soil crust reduces infiltration and can be minimized by leaving surface residue, improving organic matter levels, and enhancing biological activity. Available water holding capacity is the amount of water soil can hold for plant use. After water gets into the soil, the surface tension of water holds it in soil pores against the pull of gravity.