Agricultural Controlled Drainage

Unlike conventional subsurface agricultural drainage, controlled drainage systems manage the outlet to give farmers control over the water table. To do this, water level control structures are placed on a drainage system to “dam up” the water and raise the water table to an ideal level, depending on the growth stage of the crop. Stop-gates in the structures can be adjusted throughout the year so the water can be close to the root level (18” to 36”). A controlled drainage system holds water in the soil profile during dry periods, reducing overall drainage volume and limiting the nutrients leaving the land.

Throughout the year, stoplogs can be adjusted according to crop stage and field operations:

Controlled Drainage Tips for Each Season

Spring

Stoplogs removed to allow trafficability in the field. Allow two weeks of free drainage to reduce the water table. After planting, replace stoplogs to raise water table near root level

Summer

As roots extend down, the water table level can be lowered to promote deeper root growth. Stoplogs can be left in place through late summer to retain soil moisture during dry periods.

Fall

Stoplogs should be removed to allow for trafficability during harvest and tillage.

Winter

In southern climates, stoplogs can be set in place after harvest to raise the water table in order to limit unnecessary drainage and fall-applied fertilizer leaching. In colder northern climates, stoplogs can be removed to prevent a hard freeze in the structure.