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¶ Introduction
During severe drought conditions, some producers attempt to salvage their corn crop as forage rather than abandoning it for grain harvest. Harvesting corn as hay is one option, but has some challenges.
¶ A. General Considerations
- Check pesticide labels
- Check to verify any harvest restrictions.
- Pre-harvest interval for grain harvest likely to be different from forage pre-harvest interval.
- May be most critical for dairy animals.
- Check insurance coverage
- Policy coverage terms can differ greatly.
- Check with agent to verify terms for hay harvest.
- Growth stage
- Treat drought-damaged corn as “coarse grass”.
- Feed value can be highly variable; depends on growth stage, height, amount of drought-stress (see Table 2).
- If near-normal height, will be large volume of forage to dry down in windrow.
- Inability to dry effectively may effectively prevent use as hay crop.
- Mature stalks are tough, hard to harvest, may damage equipment.
- Mature or nearly mature corn may be best harvested as silage or green-chop.
- Hard to make good tight bales that both shed rain and are easy to transport.
- Good, dry bales should feel “light” when pushed.
- “Heavy” feeling bales probably have excess moisture.
- Large square bales may work best.
¶ B. Moisture Content
- Stalks must be completely dry before baling.
- Should be less than 20% moisture; preferably 15% moisture or less.
- Excess moisture can cause excess sweating if bales are stored under plastic.
- Stalks may need at least seven to 10 days to cure effectively.
- 2012 South Dakota report: took 30 days for swathed corn plants to dry from 68% moisture to 16% moisture.
- More than 50% moisture?
- Harvesting as baleage (round bale silage) may be feasible.
- Bales with excess moisture from poor pre-harvest dry-down can heat up during storage.
- Improperly cured plants, even below 20% moisture, can still be “alive”, growing and, respiring.
- Respiration forms wet spots and hot spots.
- Improperly cured plants, even below 20% moisture, can still be “alive”, growing and, respiring.
- Wet spots in bale can reduce feed value.
- “Heat-damaged” protein is common problem.
- Severe heating may cause spontaneous combustion, fire and flames.
- Molds can develop.
- Spoilage reduces feed quality; increases feed refusal and waste.
¶ Figure 1. Nitrate-Nitrogen Levels in Drought-Affected Corn*
¶ C. Cutting Management
- Hay must be crimped or mechanically processed to enhance field curing.
- Stalks will not dry as quickly as leaves; pith holds moisture.
- Some balers may have difficulty picking up standing stalks, so are not processed.
- Appropriate cutting height varies.
- Cutting large stalks close to ground with rotary mower or disc mower may improve bale harvest.
- Standing stalks may damage some haying equipment.
- Drawback is that including more of lower stalk usually increases nitrate content of final harvested forage (see Figure 1).
- Options to maintain some vegetative cover as needed to store water and for soil erosion control in dry areas:
- Leave 10 inches or more of stalk height if entire field is to be harvested.
- Strip harvest: leave one planter width standing; harvest next one or two planter widths to create erosion control and snow storage.
- Will remove one-half to two-thirds of crop while still leaving some residue
- Plant cover crop in fall if all residue is removed.
- Cutting large stalks close to ground with rotary mower or disc mower may improve bale harvest.
- Shredding speeds drying process; can help improve handling during baling.
- If not shredded, hay will be coarse and hard to contain because of large number of thick stems.
- Shredding reduces particle size; forms tighter bale.
- If shredded, will be lots of fines to contain.
- Extra plastic wrap may be needed for best results.
- String-tie baler precautions
- May need narrower twine spacing (e.g., 3-inch spacing).
- Put extra wraps on ends to help secure bale.
- Net wrap may be better choice than twine.
- Test harvest options on small scale.
- Some balers may have difficulty picking up fine material.
- May need to tighten down baler tension.
¶ D. Corn Hay Storage
- Corn stalk hay is less weather resistant than grass hay.
- Does not form tight thatch over top of bale.
- Allows rain water to penetrate into bale during extended rainfall.
- Causes excess weathering; hay quality deteriorates.
- Cover bales when needed.
- Store in roofed structure, under tarps, or under plastic sheeting for best results.
- Twine-tied bales take up moisture more readily than net-wrapped bales.
- Outside storage precautions.
- Chop or shred large corn plants before baling.
- Tighter, larger bales stand up to outside storage better than looser or smaller bales.
- Allow about six inches of open space between bales for air circulation.
¶ E. Feeding Corn Hay
- Drought stressed corn can have good feed value.
- Crude protein content may be higher than unstressed corn, if leaves were retained.
- Molds and spoilage are not necessarily toxic.
- Feed refusal and wasted feed are common problems rather than toxicity.
- High nitrate levels are potential concern.
- Toxicity risk increases rapidly when primary forage is above 1000 to 1500 ppm NO3-N.
¶ F. Nitrate Toxicity Potential
- No way to accurately predict nitrate levels
- Nitrate levels affected by any factor limiting plant growth while still allowing nitrate uptake by plant roots.
- Nitrate levels can change every few days.
- Depends on corn growth rate and relative amount of stress.
- Can increase rapidly following a rain as plant takes up soil water and resumes growth (see Table 1).
- Nitrate levels differ in different plant parts.
- Lower stalk typically has highest nitrate levels; leaves have lowest.
- Example from Figure 2:
- Bottom 6 inches of corn stalk:
- “Normal” plant – 150 ppm NO3-N
- Stressed plant – 8200 ppm NO3-N
- Corn leaves:
- “Normal” plant – 70 ppm NO3-N
- Stressed plant – 350 ppm NO3-N
- Bottom 6 inches of corn stalk:
- Example from Figure 2:
- Raising cutting height helps reduce nitrates in final forage by eliminating lower stalk with higher nitrates.
- Lower stalk typically has highest nitrate levels; leaves have lowest.
- Always test drought-damaged forages for nitrate before feeding.
- Harvesting as hay does not reduce forage nitrate levels.
- Testing standing corn can give indication if nitrates are potential problem.
- Pre-harvest results should not be used for making final feeding decisions.
- Higher protein levels often correspond with higher nitrate levels (note bottom portion of Figure 2).
- Do not feed high nitrate hay as “free choice”.
- Controlling consumption rate is crucial; greatest hazard is from hungry animals.
- Limit consumption rate by feeding smaller amounts, but feeding more frequently.
- Dilute high nitrate hay with low-nitrate hay or other feedstuffs.
- Include grain or concentrate in ration as needed.
- Grinding or chopping hay may be necessary to manage feed intake.
¶ G. Collecting Field Samples for Analysis
- Collect samples along transect.
- Chose random number (e.g., “17" or “23").
- Walk diagonally to row direction.
- Start walking; count number of paces or rows.
- When count is complete, (e.g., 17th row or 23rd pace); sample plant immediately ahead.
- Cut plants off at expected harvest height.
- May need long-handled pruner-loppers for thick stalks.
- Repeat procedure, proceeding along transect to collect 15 to 20 plants.
- Chop collected stalks and leaves into 2-inch pieces.
- Mix pieces in tub or on sheet of plastic.
- Collect subsample of mixed pieces by grabbing random handfuls.
- Place handfuls into gallon-size plastic zipper-lock freezer bag.
- About one to two quarts of sample is required for analysis.
- Squeeze bag to remove air and seal.
- Deliver to nearest ServiTech Laboratory by fastest means available.
- Refrigerate samples if they have to be held and cannot be delivered immediately; do not freeze.
¶ H. Collecting Samples from Bales
- Use core sampler with sharp tip.
- Collect samples from at least 20 bales that have come from a single field or single cutting.
- Collect samples from 20% of bales if field yielded more than 100 bales.
- Core as deeply as sampling tool allows.
- First few inches of bale surface will be weathered by exposure to weather.
- Shallow samples may not accurately reflect condition of inner portion of bale.
¶ Table 2. Corn Hay: ServiTech Laboratory Feed Analysis Survey Results |
||||
| Analysis | Median, mean | Typical Range | ||
| Dry Matter, % | 85.7 | 78.2 | – | 90 |
| Moisture, % | 14.4 | 10 | – | 21.8 |
| Ash, % | 11.2 | 8.33 | – | 16.5 |
| Crude Protein, % CP | 8.8 | 6.6 | – | 11.1 |
| ADF insoluble nitrogen, as % CP | 1.3 | 1 | – | 1.4 |
| Acid Detergent Fiber, % ADF | 39.9 | 33.4 | – | 46.7 |
| Neutral Det. Fiber, % NDF | 61.9 | 51.6 | – | 70.9 |
| Crude Fiber, % CF | 35.2 | 26.2 | – | 36.9 |
| Crude Fat, % | 0.6 | 0.4 | – | 0.8 |
| Relative Feed Value, RFV | 87 5 | 76.5 | – | 98.2 |
| Total Digestible Nutrients, % TDN | 57.9 | 50.7 | – | 65.1 |
| Net Energy, Maintenance, Mcal/lb | 0.56 | 0.45 | – | 0.67 |
| Net Energy, Gain, Mcal/lb | 0.31 | 0..02 | – | 0.4 |
| Net Energy, Lactation, Mcal/lb | 0.59 | 0.51 | – | 0.67 |
| Metabolizable Energy, Mcal/lb | 0.95 | 0.83 | – | 1.07 |
| Digestible Energy, Mcal/lb | 1.14 | 1 | – | 1.3 |
| Calcium, Ca % | 0.425 | 0.35 | – | 0.538 |
| Phosphorus, P % | 0.17 | 0.09 | – | 0.22 |
| Magnesium, % Mg | 0.265 | 0.21 | – | 0.32 |
| Potassium, % K | 1.56 | 1.16 | – | 2.03 |
| Sodium, % Na | 0.01 | 0.01 | – | 0.02 |
| Sulfur, % S | 0.1 | 0.08 | – | 0.13 |
| Copper, ppm Cu | 8 | 6 | – | 9 |
| Iron, ppm Fe | 1250 | 667 | – | 2430 |
| Manganese, ppm Mn | 89 | 71 | – | 143 |
| Zinc, ppm Zn | 30 | 18 | – | 38 |
¶ Figure 2. Comparison of Plant Parts from Stressed and “Normal” Corn
¶ References
Hicks, D.R. and P.R. Peterson. 2006. Using drought stressed corn for forage. Minnesota Crop eNews, Univ. of Minnesota Ext. Serv. 26 July 2006.
Hutjens, M. 2002. Strategies with drought-stressed corn. Dairy Decisions Column, Univ. of illinois, Urbana, IL. 06 August 2002. Higbee, J.M., et. al. Nitrate hazards to livestock. Mimeo from Univ of Wisconsin Coop. Ext. Svc. Recd. 12 Oct 1976 by KSU Veterinary Diagnostic Laboratory.
Johnson, et. al. 2022. Dryland corn considerations for 2022. Agronomy eUpdate 3919, Aug. 11, 2022. Kansas State Univ. Res. & Ext., Manhattan KS. https://eupdate.agronomy.ksu.edu/article_new/dryland-corn-considerations-for-2022-507-4 accessed 11 Jul2023.
Klein, R. 2017. Should you hay or cut silage from drought-damaged corn fields. CropWatch, Univ. of Nebraska Coop. Ext., Lincoln NE. 28 July 2017 https://cropwatch.unl.edu/2017/should-you-hay-or-cut-silage-drought-damaged-corn-fields accessed 10Jul2023.
Lardy, G. 2004. What to do with immature corn. North Dakota State Univ., Agric. Communications news release, 26 August 2004. http://www.ext.nodak.edu/extnews/newsrelease/2004/0819 04/14cornca.htm accessed 07/05/11.
Poore, M. and J. Turner. Corn stalks and drought-damaged corn hay as emergency feeds for beef cattle. College of Agriculture., North Carolina State Univ. http://www.ces.ncsu.edu/disaster/drought/corn_stalks%28u pdate%29.pdf, accessed 07/05/11.
Wright, D.L. and H.E. Jowers. Using drought stressed corn for silage, hay, or grazing. Univ. of Florida Extension. Pub. no. SS-AGR-274.