PRIMGHAR, Iowa — History has shown that drought years in late summer pose the highest risk of a runoff water quality violation.
The environmental standard for small Iowa feedlots is that a farmer settles out the settable solids before the runoff water leaves the property and that there is no water quality impairment. Under normal conditions, we focus on designing a system that will be capable of removing the solids without worrying about the second part. During droughts, the need to be able to keep all of the runoff on our property is more important because of the following conditions:
- Creeks are very low with very little drainage flow. The fish are in high concentrations in a few deep pools.
- Water is warm and contains very low dissolved oxygen.
- The oxygen need of the fish is the highest with warm fish body temperatures.
- The cropland is very dry and will soak up all of the rainfall. The feedlots will be the only runoff water that enters water courses.
- Concrete lots are often stocked at high densities causing quick runoff because of the water consumption of the cattle. Lots often runoff before anything else does that could provide dilution.
Action to take:
- Keep the lots clean and stockpile dry manure even in the yard.
- Make sure that all of the components of the runoff control system are working.
- Watch the forecast especially for the ½-inch to 1-inch rains that will only cause runoff from the feedlots.
- Water in settling basins should be pumped onto crop fields or grassed areas where it can completely soak into the soil.
- Consider upgrading the system to include a small pump that can turn on and direct this runoff water into a field where the crops will benefit from it and the water is protected.
Two free publications that can help are:
Inexpensive Pumping Systems to Manage Small Feedlot Runoff: http://www.iowabeefcenter.org/information/IBC52.pdf
Small Feedlot Runoff Management Using Low-Pressure Flood Irrigation: https://store.extension.iastate.edu/Product/14042
— Kris Kohl, Agricultural Engineer
Iowa State University Extension and Outreach
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