Dry, hot weather combined with manure application or irrigation can have unintended consequences.
Cracks in the soil can provide a near direct line for manure to reach a stream. The same weather conditions can cause problems in earthen basins used to store manure, according to the Department of Natural Resources (DNR).
"We don't want to add to livestock farmers' stress levels, but we've had similar conditions a few years ago and had several fish kills and water quality problems," said Cindy Martens, an environmental specialist in the Iowa DNR's Spencer field office. "Farmers think it's dry and the liquid manure will just soak in. They may want to irrigate to provide moisture to the crop, but often they don't realize how fast it can travel straight to a tile line and then into a stream. We just want people to be aware that it can be a problem, so they can do something about it."
Martens said the problem is most likely to occur when farmers start to irrigate a crop or spread liquid manure on alfalfa or pasture. "I've also seen problems in dry years with a gated pipe going from a basin to a crop field," she said. "And some of our field staff are seeing big cracks in the walls of earthen basins."
If manure application is necessary, the DNR has the following tips to help reduce the risk of manure going to a stream:
- Check for cracks in the soils before applying. If soils are cracked, delay application until soil moisture increases, if possible.
- Find all underground tile inlets and where tile lines outlet into streams or ponds. Cover or block off any inlets.
- Have emergency spill kit and information on hand before applying.
- Check the nutrient or manure management plan for required separation distances from streams, lakes and other sensitive areas.
- Consider a setback for injected manure, even when it's not required.
- Apply at the slowest possible rate.
- Move hoses and irrigation equipment frequently.
- Check tile outlets before, during and after application.
- If it rains or the outlet is discharging, check tile outlets and the stream or pond below the outlet for odor, solids and impacts to fish or other aquatic life such as crayfish.
- Stop applying manure immediately if manure is discharging.
- Contain and clean up any spilled manure.
Producers are required to call the DNR 24-hour spill line (Iowa: 515-281-8694) to report spills or discharges as soon as possible or within six hours of the discovery or beginning of the spill.
"The sooner farmers call, the better, because the DNR has trained specialists who can help contain the manure," said Martens. "The quicker they are notified, the more likely they can help producers minimize damage to fish and water quality downstream.
DNR specialists also advise checking the berms of earthen basins frequently. If there are large cracks or signs of leakage, the producer may need to wet down the berm or fill the cracks.
Producers can also request technical assistance from their local DNR field office.