Most farmers are fully aware of the benefit drain tile provides to land in our area.
In fact, three farm infrastructure investments that never concern Suzy Martin, a Farm Management Specialist with the Ohio Valley Farm Analysis Association, are the installation of irrigation systems, grain storage systems, and soil drainage systems.
These three investments are essentially guaranteed to increase farm income over their useful service life, therefore considered a wise investment for your land.
The return on investment of sub-surface systems is evidenced by the thousands of acres of land tiled in our area each year at a cost ranging from $600 to $1,000 per acre.
Yet I do frequently find myself in conversation with lenders, landowners, municipal service providers, and farmers who either don’t fully understand how it works, why it is beneficial, or if the yield change will ever pay for the installation cost.
Most of the Green River Area, Hopkins, and Northern Muhlenberg County comprise a geological area known as the Illinois Coal Basin.
This area is relatively level to rolling, with deep soil and depth to bedrock. Our soil, combined with annual precipitation exceeding 50 inches most years, presents high winter and spring water tables that delay soil drying.
This results in uneven soil drying, and ultimately reduces yield and increases production expense. The function of sub-surface drainage is a perforated plastic pipe in diameter ranging from 3 inches to 8 inches is buried beneath the soil surface on a continuous grade.
Excess soil moisture to a depth of three feet below the surface gravity drains to the pipe, providing a path of least resistance out of the soil profile.
Only water moved by the force of gravity from large soil pore space is released. Water retained in small pore spaces remains available for the plants.
Roots cannot grow in complete water saturation. In the spring, a poorly drained soil field surface may dry enough to allow planting to occur but as roots go down, they soon meet a bed of water beneath the surface resulting in shallow rooting depth early in the season.
Eventually, the water table lowers as the summer growing environment increases but by then there is a large growing crop with shallow rooting depth.
This results in decreased production and yield in drier years. The advantage of drainage is roots are able to grow deeper earlier in the season due to increased air volume in the soil.
When the summer growing season is underway, roots are deeper, providing access to subsoil moisture during drier periods.
Flooding is a problem in most counties near creeks and tributaries. I have heard it said by a local municipal service representative that continuous flowing drain tile before and during heavy rain events contributes to flooding. That is not true.
Poorly drained soil types improved by subsurface drainage, actually help alleviate flooding, not contribute to it. In the spring, when flooding typically occurs, the water table is high.
When oxygen in the large soil pores is continuously displaced by water, the soil cannot hold additional moisture, forcing rain water to immediately move off of the field surface and into rising streams and creeks.
Poorly drained soils improved with drainage are continuously draining the large pores during periods of high water tables, allowing those fields to absorb larger volumes of rain water, releasing the excess water from the large pore spaces slowly during the days following the rain event.
In reference to up-front cost, tile does provide a positive return on investment through increased yield. Yes, for landowners renting land for cash, or crop-share the return on investment occurs more slowly than those receiving all of the increased yield revenue, but drainage systems benefit beyond the annual rent income.
As mentioned, drain tiles increase water movement beneath the soil and decrease water movement above the surface.
This inherently decreases soil erosion, especially when surface water drains are installed in zones where large volumes of water movement occur.
Secondly, the cost of tile has increased, but so has the value of owned land and the cost to purchase additional.
As mentioned above, Suzy’s advice is to ensure maximum productivity of land you already possess before adding more acres. The maximum production of current property is what may make the next purchase cost manageable.
Clint Hardy is the agricultural extension agent for the Daviess County Extension Office. He can be reached at 270-685-8480.