Drainage class is probably the most important soil characteristic influencing choice of management options, and failure to consider drainage when planning production programs is a common reason for poor crop performance. “Drainage” refers to how long during the year soils are saturated at or near the soil surface. The presence of such a saturated zone can affect root health, soil fertility, and the ability to work the soil safely. Due to the importance of this phenomenon, all Ohio soil series are classified by drainage.
The more common drainage classes include:
Well-drained soils. These soils rarely become saturated near the surface. They generally occur on sloping sites, where significant runoff reduces the amount of water infiltrating the soil. They usually do not require drainage improvements and can be worked relatively early in the spring, but they can be sensitive to drought during the summer.
Somewhat poorly drained soils. These soils often become saturated near the soil surface for moderate lengths of time particularly in late winter and early spring. They often are modified by drainage improvements to allow earlier field work, improve root health, and reduce nitrogen losses due to denitrification. These soils are extremely widespread in Ohio's crop-producing regions.
Poorly drained and very poorly drained soils. These soils readily become saturated at or near the surface and may remain saturated or even flooded well into the spring or early summer. They are also prone to becoming resaturated or flooded during heavy summer storms. They occur on level or depressed areas on the landscape. A common characteristic of these soils is a relatively high concentration of organic matter in the topsoil, giving them dark-colored surface horizons and excellent productivity when drained artificially. Without drainage improvements, however, they are prone to much-delayed planting, denitrification, manganese deficiency, poor root development, depressed nodule activity in legumes, and serious root diseases. These soils can be Ohio’s most or least productive ones, depending on how well they are managed.
Drainage improvement, though expensive, is among the most profitable actions a crop producer can take. Improving drainage on more poorly drained soils expands production options, reduces many problems, and usually improves yields in wet and dry years alike. Crop rooting, soil biological activity, fertility, and water use efficiency can all be improved by removing excess water from soils. Drainage can be improved in a number of ways—by grading land to eliminate low spots and promote managed runoff, installing surface drains and ditches to collect water and channel it safely off the field, and by installing perforated plastic pipe below the soil surface to collect and remove excess water from the soil profile (i.e., tiling). Installing such practices and structures requires detailed analyses and procedures. Producers are urged to consult drainage contractors and specialists for assistance.