Soil drying will be slowed and planting or other field operations may be delayed. The fine textured layer will help to hold more water in the soil than the coarse layer is normally able to. Finer texture over coarse The finer textured soil layer has smaller pores. Water is held very tightly in those pores by capillary forces. Water will accumulate in the soil until there is enough pressure to force the water to flow from the smaller pores into the larger pores in the coarser soil layer.
Water moves more slowly through the finer textured soil, so drainage can be a problem.
Soils with an underlying coarser layer can hold as much as twice the water that a soil made of only the finer textured material holds. These soils are slow to drain and warm in the spring. Depends on the soil type. Sandy soils especially can have twice the water storage ability and if there was no coarser layer present. A thick horizontal layer of crop residue such as corn stalks, plowed under can behave much like a coarser textural layer.