Assessing and Harvesting Downed Corn - UNL CropWatch, Oct. 26, 2012

Assessing and Harvesting Downed Corn - UNL CropWatch, Oct. 26, 2012

October 26, 2012

Also see Robert Klein's photo essay on an operation's effort to harvest downed corn and a related segment on YouTube from the November 2 Market Journal story with Rick Rasby.

Corn growers in central and western Nebraska are facing a new challenge after high winds swept through unharvested fields October 17-18, knocking down stalks or stripping ears from still-standing stalks. Now growers are having to figure out how to gather as much as 100 bu/ac of corn from the ground.  Corn that's too low to pick up with a standard corn head and often too much to safely turn cows into without a lot of management.

Downed corn from 1/1000th of an acre

Above: Following the Oct. 17-18 windstorms in central and western Nebraska, an assessment of downed corn in this western Keith County field found 14 ears on the ground in a row length equal to 1/1,000 acre. This represents about a 70 bu/ac loss, unless it can be harvested by man, machine, or animal.  See story for how to assess the amount of downed corn in a field. (Photos by Bob Klein)

wind damage in western Keith County

Figure 2. Winds of up to 70 mph took their toll on corn fields in central and western Nebraska Oct. 18. leaving farmers to grapple with how to recoup their lost yield from the ground.

It’s only the next hurdle in a year full of challenges, but it's a big one with corn at $7-$8 a bushel.

With this summer’s drought, much of the dryland corn had been harvested early for silage. However, when the storms hit, areas of north central and western Nebraska still had corn in the field as growers, particularly in higher elevation areas, waited for it to dry down.

Many of these affected acres were higher yielding, irrigated acres. The extent of loss varied from field to field, but appeared to be worse with some hybrids.

Now producers are assessing the loss and looking for how best to proceed to gain back as much yield and profit as they can.

As with any crop loss, contact your crop insurer to review your coverage before taking any action that might affect it.

One grower in Holt County is reported to have 15-20 quarters of corn with 50-100 bu/ac on the ground.  Estimates for other fields were up to 150 bu/ac on the ground.

And, as if the loss isn't enough of a problem, if growers can't get this corn out of the field by spring, large areas of volunteer corn will be their next challenge. 

Harvesting — From the Ground Up

A survey of extension educators and specialists working with affected farmers indicated there is no simple solution to harvesting the downed corn. Some farmers are first harvesting any standing corn with a combine, then returning to the field to try to reclaim the corn on the ground through one of several routes.

Some growers are using a V-rake to window the stalks and then coming back in with a windrow pick-up (bean) head on their combine to pick up stalks and ears from the ground. Harvest needs to be slow, as little as 1.5 mph, and the stalks and clumps of dirt will be hard on the combine and may cause it to plug.  One grower had good luck tieing down the rake's wheels to keep them from riding up and floating over the corn stalks. Not surprisingly, this harvest process can be hard on rake teeth.

Other growers are using a flail chopper to finely cut the standing stalks and leaf material, then using a hay rake to gather the cut material and corn on the ground into windrows. Then they are using a combine with a windrow pick-up bean head set to run close to the ground.

After the flail chop, other growers are baling up the plant material and corn and processing it for feed. It's recommended that the nutrient content of the feed be tested due to the above average level of corn it contains.

Some growers also have looked into rock pickers.

Others are going the human route and paying FFA  or other youth groups to manually harvest affected fields.

Feeding Livestock

Depending on the amount of grain left in the field and the difficulty of mechanical harvest, livestock feeding may be a good option for some growers. On, UNL Extension Educator Rick Rasby notes that feeding weaned calves or yearlings would be an option. With this much corn, you would want a class of livestock that you would want to put pounds on as compared to maintaining weight (cows that are gestating). Both are inexperienced at grazing corn residue and will slowly adapt themselves to the high grain diet. They will first graze the perimeter and any grass waterways, then the corn. Both would need to be supplemented with protein and with an ionophore to counter potential acidosis.

Cull cows also may be an option. Most cows will be experienced corn stalk grazers and will find the corn quickly and founder will be a concern. Fill the cows up with hay before turning them out on these fields. Although cull cows will not need a protein supplement, it would be good to add an ionophore in a supplement.

Rasby says he would not graze pregnant cows unless the fields were pregrazed with either weaned calves, yearlings, or cull cows. If you could get the ear drop to three to five bushels per acre, there would be less risk with pregnant cows.

In some cases, the amount of grain in the field may require that grazing areas be limited by cross-fencing or over stocking. Even with excellent management, some calves may founder.

Strip grazing limited areas throughout the fall and winter requires a lot of time and continual management, but may be one of the best ways to harvest these fields with livestock. If the ground freezes and you're still regularly moving an electric fence, a rechargeable hand drill can be handy for drilling in frozen soil to create a hole for a for an electric fence rod.

Determining the Level of Corn Loss

Table 1.  Row length equal to 1/1000 of an acre for various row widths.

Row Width Row length equal
to 1/1000 acre

15 34 ft 10 in
18 29 ft 0 in
20 26 ft 2 in
22 23 ft 9 in
30 17 ft 5 in
36 14 ft 6 in
38 13 ft 9 in

One method to determine corn loss is to count the number of ears on the ground between two rows on 1/1000 of an acre. The distances required for several row widths are listed below. It is best to count several areas and average the loss.

First, count the number of kernel rows and kernels per row on an ear. Next, use one of the following tables to determine the bushels/acre represented by each ear. Table 2 is used for average size kernels, and Table 3 is to be used for small kernels. For example, if the average ear has 16 kernel rows and averages 45 kernels per row with average kernel size, each ear represents 8 bu/ac. If you find five ears in 1/1000 of an acre, your loss is 40 bu/ac.

Lisa Jasa, CropWatch Editor
Robert Klein, Extension Western Nebraska Crops Specialist
Bruce Treffer,
Extension Educator, Dawson County
Gary Stauffer, Extension Educator, Holt County

Rick Rasby, Extension Beef Specialist
Keith Glewen, Extension Educator, Saunders County

Table 2. Bushels per acre for each ear found in 1/1000th of an acre (17.4 foot row length in 30-inch rows) with average kernel size (90,000 kernels per bushel)

  Kernels per row
 No. of rows
per ear
25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

12 3.3 3.6 3.9 4.1 4.4 4.7 4.9 5.2 5.5 5.7 6.0 6.3 6.5 6.8 7.1 7.3
14 3.9 4.2 4.5 4.8 5.1 5.4 5.8 6.1 6.4 6.7 7.0 7.3 7.6 7.9 8.2 8.6
16 4.4 4.8 5.2 5.5 5.9 6.2 6.6 6.9 7.3 7.6 8.0 8.3 8.7 9.1 9.4 9.8
18 5.0 5.4 5.8 6.2 6.6 7.0 7.4 7.8 8.2 8.6 9.0 9.4 9.8 10.2 10.6 11.0
20 5.6 6.0 6.4 6.9 7.3 7.8 8.2 8.7 9.1 9.6 10.0 10.4 10.9 11.3 11.8 12.2
22 6.1 6.6 7.1 7.6 8.1 8.6 9.0 9.5 10.0 10.5 11.0 11.4 12.0 12.5 13.0 13.4

Table 3. Bushels per acre for each ear found in 1/1000th of an acre (17.4 foot row length in 30-inch rows) with small kernel size (115,000 kernels per bushel)

  Kernels per row
No. of rows
per ear
25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

12 2.6 2.8 3.0 3.2 3.4 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 5.7
14 3.0 3.3 3.5 3.8 4.0 4.3 4.5 4.7 5.0 5.2 5.5 5.7 6.0 6.2 6.5 6.7
16 3.5 3.8 4.0 4.3 4.6 4.9 5.4 5.4 5.7 6.0 6.3 6.5 6.8 7.1 7.4 7.7
18 3.9 4.2 4.5 4.9 5.2 5.5 6.1 6.1 6.4 6.7 7.0 7.4 7.7 8.0 8.3 8.6
20 4.3 4.7 5.0 5.4 5.7 6.1 6.8 6.8 7.1 7.5 7.8 8.2 8.5 8.9 9.2 9.6
22 4.8 5.2 5.5 5.9 6.3 6.7 7.1 7.5 7.8 8.2 8.6 9.0 9.4 9.8 10.1 10.5