As cover crop acres increase throughout the Midwest, some farmers have questions about possible unintended consequences. Last spring, a few growers in central Indiana reported tile blockages due to roots.

Some assumed that cover crop roots were the culprit. Yet cover crop acres have increased the past 5 years, and almost no issues were reported in prior years. Cover crops significantly help reduce soil erosion, keep nutrients from leaching, and increase soil organic matter.

Here are the top five things farmers should know about regarding potential roots in tile drains, according to the Soil Health Partnership:

  1. Weather can be a major factor. The warm fall of 2015 and mild winter of 2016, followed by the very warm March and wet April resulted in more cover crop top growth and perhaps more root growth than normal. An Ontario, Canada report suggested that roots grow downward in the soil profile to reach available water if there is not enough moisture in the upper soil layers.

    “Roots may enter a dry tile, but are unlikely to proliferate if there is no water there,” says Dan Towery, a Soil Health Partnership field manager for Indiana. “Once water starts flowing again, the roots may flourish.”   
  2. Tile blockages are more likely to occur in tile with flat grades (0.1%). Surface inlets may allow crop residue (after vertical tillage sized the residue) and sediment to enter the tile. In addition, if a tile-plow hit a rock during tile installation, a dip or hump may have resulted. This then could cause water, sediment and debris to pond in the tile and allow roots to grow.
  3. Using non-manufacturer internal couplers and lateral connectors may catch residue or other debris and eventually plug the tile.  
  4. A tile outlet that is submerged under water reduces the flow and will cause the water in the tile to back up. This may enhance root growth in the tile over a period of time.
  5. If a previous owner of a rural house hooked the septic tank effluent directly into a nearby tile instead of installing a filter field, or as relief outlet to the leach field, the steady trickle of water and nutrients into the tile may provide a great environment for root proliferation. 

Towery says it’s not certain that cover crop roots caused the blocked tile in the cases in Indiana. It could also have been crop roots from the year before.

“It seems that a perfect storm of multiple things caused the tile to become blocked,” he explains. “These conditions may not happen for another 20 years, if ever. And the number of fields affected was extremely small. We don’t want this to stand in the way of progress in adopting cover crops.”

Towery invites farmers to give the SHP feedback if this occurred on your farm. The more information shared, the better the chance of getting to the root of the problem, he says. Visit the Soil Health Partnership website for more.