Orchards require a well-drained soil in order for roots to have good aeration and to function properly. The soil is unsatisfactory for orchard purposes if the water table remains within six inches to a foot of the soil surface for a week after a heavy spring rain, or within three feet of the surface for several weeks after growth starts. Poor internal water drainage is a limiting factor for many sites. In Kentucky, many orchards are on soils with a fragipan which result in perched water tables near the surface during winter and spring months. Perched water tables exist above the fragipan only during months when precipitation exceeds evapotranspiration. This often results in extended periods of water saturation of the top two to three feet of the soil. For good growth and optimum production, internal water drainage needs to be improved.
Brown, Gerald D.; Wolfe, Dwight E.; and Murdock, Lloyd W., "Effectiveness of Tile Drainage on a Fragipan Soil in an Orchard Site" (1997). Agronomy Notes. 15.