On Aug. 10, 2020, farmers in central Iowa experienced one of the worst natural disasters to ever affect agriculture in our state. The 2020 derecho event flattened and destroyed corn fields in at least 36 counties. Government agencies and conservation groups are working to establish assistance programs for those affected to try to salvage what they can from their fields.
Planting a cover crop in these destroyed fields is a priority that will at least provide a living root in the soil profile. This will help long term by feeding the soil biology to keep it healthy. The cover crop roots will capture some of the excess fertility present in the soil that will not be utilized by the crop, before it moves out of the soil profile and into tile lines and surface water. Nutrients applied to a corn crop that will not be harvested will eventually leach out of the residue and into the soil. Being able to get a cover crop planted on these acres should more than pay for itself in improved weed control and reduced fertilizer expenses next year. Also, without the crop canopy, a winter annual like cereal rye will have a great chance to get well established before winter.
In northern Iowa, thousands of acres of cover crops were aerially seeded during the past two weeks. The current rainy weather came at just the right time to allow the seed to germinate. The advantages of cover crops applied to the drought and heat damaged crops we have this year are the same as in the wind damaged area. Crops were fertilized with the expectation of a larger yield and nutrient removal by the grain. A deep-rooted cover crop that continues to grow all winter will salvage much of this excess and expensive fertility. It may be difficult for a producer to put more resources into a crop that will not yield as expected, but planting cover crops is a great jump start to next year’s crop. In addition, you will be helping to keep some soluble nutrients out of the water supply.
The Des Moines Water Works reported two weeks ago that algae blooms in the water of the Des Moines River that are caused by excessive nitrogen and phosphorus combined with exceptionally warm temperatures has made it impossible to use the river as a water source for Des Moines. This is a major announcement that did not get the press coverage it deserved. The city will eventually need to drill wells to reliably obtain the water it needs for Iowa’s largest metro area. The fact that the surface water in the Des Moines River is now so polluted with agricultural nutrients that they can no longer be economically removed, is an indication of how much work needs to be done in educating producers and landowners on how to keep applied nutrients from leaving their property.
As with so many environmental issues, waiting for government or industry to finally act is usually too late. Using cover crops, especially this year, is an environmentally sound practice that actually makes money for the producer, and in many situations can be subsidized with federal, state or local watershed funds.