Nitrogen makes up 78% of the air we breathe. It is an essential plant nutrient, an important element in our food supply and responsible for lush green lawns in springtime. So what’s not to like? Well as we learned as kids with candy, too much of a good thing at the wrong time/place can be bad for you.

In the news recently we have read about hypoxia, or the lack of dissolved oxygen in the Gulf of Mexico and other marine dead zones around the US and worldwide. The dead zone in the Gulf is over 22,000 square miles (about the size of New Jersey) affecting prime shrimp fishing grounds. The nutrient rich runoff from the Midwest is a major contributor to this oxygen starved marine environment.

Two local programs in Indiana are taking steps to research and introduce farming practices that will reduce the amount of nitrogen in agricultural runoff. Recently a work shop was held by the Agricultural Drainage Management Coalition, the Conservation Technology Information Center and Purdue University on Drainage Water Management. Simplistically, this technique is the installation of a control structure at the outlet of a drain tile system so that the amount of subsurface water in a field can be controlled.

Control Structure

The outlet is raised after harvest to retain water over the winter and reduce the volume of water drained from the field an the subsequent nitrate delivery. A few weeks before planting, and harvest, the outlet is lowered to allow the field to drain fully. After planting the outlet is raised to store water for the crops with the potential of increasing yields and again to limit nitrate runoff.

Studies have shown that in Indiana most nitrate runoff occurs after harvest in the fall and winter when much of the soil drainage takes place. With proper management there is a potential to improve crop yields somewhat and more research is needed to better define it quantitatively. There is some indication that there is a real yield benefit from drainage management in years when yields are low.

Drainage management is eligible under the new Farm Bill for cost sharing through EQUIP and the CSP programs (final rules are being developed now). With no new land being put into production since 1985 and the loss of agricultural acreage to development it is important to look at new practices to increase bushels per acre.

The second method that shows good promise on reducing nitrate runoff is planting cover crops in the winter. The Eagle Creek Watershed Alliance has worked with a farmer in Hendricks County using annual rye grass as a winter cover crop. Rather than reducing nitrate runoff by “storing” it in subsurface water, the rye grass will use the nutrient and accumulate, in some studies, an average of 40 lb of nitrogen per acre. Again more research is needed as data was inconclusive due to a lack of rain the first year – good for runoff to the Gulf, bad from a farming and academic point of view.

For more information on drainage management refer to any of the following: Agricultural Drainage Management Coalition, Questions and Answers About Drainage Water Management, Purdue Agricultural Drainage website and the NRCS Standard Practice 554.