Field tile won’t be only the option for farmers and their land

By Bill Northey

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As we enter spring, it is an exciting time for farmers. The warmer weather makes them anxious to begin the process of planting, caring for and harvesting a crop from the tremendously productive soil in our state.

One of the tools that helps farmers be so productive is tile drainage, which is a system of pipes running underneath farm fields that drain standing water from the field and allow agricultural production. Lately, there's been a lot of talk about the impact of tile drainage on flooding and water quality.

University research shows that tile drainage in farm fields reduces peak storm flows by moving water out of the soil profile, thereby leaving space for the rainwater to soak into the ground rather than run off across the surface. This slow release prepares the soil surface for more rainfall later. Tile drainage is also an important component of other soil conservation practices.

A drier field helps with soil integrity, which means less surface erosion during a time when there seems to be no end rains or thunderstorms. Better soil integrity also helps keep the nutrients in the field and out of our rivers and streams by reducing erosion from surface runoff and allowing water to be filtered by infiltrating through the soil.

But, there are limits when it comes to slowing down the water and protecting our fields. The record 2008 rains saturated the soil. When this happens, rain water is going to runoff whether there's tile, terraces, or prairie grass; it's just too much water to handle.

There's also discussion about nutrients (nitrates) coming out of tiled fields. Our fields naturally have a high organic matter content, which is what makes them so productive, and corn requires nitrogen in the soil to grow. So, when water goes through our nutrient-rich soil, it can pick up that nitrogen, which then flows through the tile lines. The result is tile water is higher in nitrates and lower in other pollutants.

Farmers continue to work on ways to reduce this nutrient loss. There are new and developing technologies and techniques that are showing great progress in reducing nitrates in tile drainage, such as targeted wetland restorations, bioreactors and controlled drainage.

The Iowa Department of Agriculture and Land Stewardship (IDALS) is working with the Department of Natural Resources (DNR) and water quality researchers at Iowa State University to put together a state nutrient-reduction strategy. This strategy will identify the soil, water and nutrient management practices that are most effective and give farmers even better tools to ensure Iowa's continued place in successful crop farming, while improving the sustainability of Iowa's fertile soils and the quality of Iowa's waters.

Bill Northey, a fourth-generation corn and soybean farmer from Spirit Lake, is serving his second term as Iowa Secretary of Agriculture. Comments: agri@iowaagriculture.gov