Using drainage tile provides a plumbing network under fields that extensively drains the land, making it more easily farmed. Drained water, however, is a major source of nitrate and phosphorus runoff. Controlling the nutrients that leave fields and enter waterways is something Jane Frankenberger, professor of agricultural and biological engineering at Purdue University, is working on improving.
“Excess water is the most common agriculture issue we address. Ponded water can reduce yield if it is staying too long and can be a problem with spring fieldwork,” Frankenberger said during a recent Partnership for Agricultural Resource Management presentation. “Tile drains are the broadest source of nitrate loss and recent research is showing more clearly that they are a major pathway for phosphorus runoff.”
To stem the problem, researchers are looking at ways water can be stored or managed inside an agriculture system. These include having two-stage ditches, placing stops in the drainage tile that would allow the water table to be raised or lowered depending on the time of year and water needs, and digging storage ponds on site to store the nutrient-rich water and using it later for irrigation.
“Despite excess water in spring, yields are often limited by the lack of water in late summer,” Frankenberger said. “We need to work together so that the process of designing and implementing agricultural drainage will be transformed to include water retention and even water recycling.”
Charlie Schafer of AgriDrain Corp. said drainage tile was initially used to make saturated soils farmable. He said going forward, drainage tile could be used to not only drain unwanted water but also irrigate during dry times and return lost nutrients to fields.
“We want to drain only as much water as needed to ensure equipment access and healthy crop production,” Schafer said.
Schafer said systems are beginning to be designed to use stop logs that can raise and lower the water levels in the soil as needed. This means fields can be drained in the spring for accessibility and to also warm the soil and encourage plants to establish strong roots. Then in the summer, the system could raise the water level in the soil to encourage deeper rooting of the plants. In the fall, the water could be lowered again for harvest and then raised in the winter for storage of water and nutrients.
Schafer said using these systems could not only reduce nutrient runoff but help save money in irrigation costs. They also could help fields produce more consistently from year to year by taking away some of the water availability concerns.
“These producers want to do the right thing environmentally, but they also need to have an incentive to do it,” Schafer said. “If we allow farm fields to continue to be drained as they are without management, we miss an opportunity.”