in soil science and agronomy, soil compaction is usually a combination of both engineering compaction and consolidation, so may occur due to a lack of water in the soil, the applied stress being internal suction due to water evaporation as well as due to passage of animal feet. affected soils become less able to absorb rainfall, thus increasing runoff and erosion. plants have difficulty in compacted soil because the mineral grains are pressed together, leaving little space for air and water, which are essential for root growth. burrowing animals also find it a hostile environment, because the denser soil is more difficult to penetrate. the ability of a soil to recover from this type of compaction depends on climate, mineralogy and fauna. soils with high shrink-swell capacity, such as vertisols, recover quickly from compaction where moisture conditions are variable (dry spells shrink the soil, causing it to crack). but clays such as kaolinite, which do not crack as they dry, cannot recover from compaction on their own unless they host ground-dwelling animals such as earthworms — the cecil soil series is an example.