Controlled Drainage

Controlled drainage has been used on wet soils reduce nitrogen losses and provide subsurface irrigation for a number of years.  Researchers have studied the discharges of tile drained field and found the water discharged does not meet drinking water standards for nitrates.  Structures like this can be installed relatively inexpensively to control water table levels in the soil, letting water tables be high in the winter and then lowering them in the spring.  After the crop is growing, water drainage can again be reduced to conserve moisture.  This practice is sometime called subsurface irrigation. 

In the November-December issue of the Journal of Soil and Water Conservation, researchers from North Carolina reported a 10% increase in corn and soybean yields on fields with controlled drainage.  They also reported no change in wheat yields.  Controlled drainage works best on extremely flat fields.  In situations where fields are more sloping, you might need to do d a cost analysis to see if it is worth the effort.