Drought-stressed corn is a common challenge during dry growing seasons, but it does not necessarily result in a total loss of feed value. With proper harvest and storage management, drought-damaged corn can remain a useful and economical forage source. Although yield reductions are often unavoidable, appropriate ensiling practices can help producers capture much of the remaining feed value while minimizing storage losses.
Effects of Drought Stress on Corn
Drought stress alters normal corn growth and development. Under water-limiting conditions, plants close their stomata to conserve moisture, reducing cooling and slowing photosynthesis and other physiological processes. As a result, drought-stressed corn often exhibits:
- Reduced or incomplete ear and kernel development
- Lower starch accumulation in grain
- A greater proportion of stalk and leaf tissue relative to grain
- Changes in fiber development and plant structure
- Highly variable forage quality within and between fields
Although drought stress generally reduces yield, forage digestibility and nutrient composition can vary considerably depending on the timing, severity, and duration of the stress.
Harvest and Utilization Options
Several options exist for utilizing drought-stressed corn.
Corn Silage
Ensiling is generally the most effective way to preserve feed value. Harvesting the entire plant captures available nutrients and allows fermentation to stabilize the forage.
Grazing
Grazing can reduce harvest costs but may result in uneven utilization, increased trampling losses, and difficulties controlling animal intake.
Baleage
Drought-stressed corn can be harvested as baleage, but coarse stalks may puncture plastic wrap, increasing oxygen exposure and the risk of spoilage.
Dry Hay
Producing dry hay from whole-plant corn is generally not recommended because of its high moisture content and slow drying rate.
Harvest Timing and Yield Estimation
Timely harvest is essential to minimize additional field losses and declines in forage quality. Drought-stressed corn often dries unevenly and may accumulate nitrates, particularly in the lower stalk.
For severely drought-damaged corn with little or no grain development, a common field estimate is approximately 1 ton of 30% dry matter silage per foot of plant height (excluding the tassel) (National Corn Handbook, Utilizing Drought-Damaged Corn).
Moisture Management
Proper moisture at harvest is critical for successful fermentation.
Target Levels
Target moisture levels include:
- Horizontal bunker or pile: 63-68% moisture
- Upright silo: 60-65% moisture
- General target: 65-70% moisture at harvest
Excessive Moisture
Risks of excessive moisture include:
- Nutrient loss through seepage
- Poor fermentation and reduced intake
- Butyric acid formation and off-odors
- Environmental concerns from effluent
Low Moisture
Risks of low moisture include:
- Poor packing and oxygen exclusion
- Heating and mold development
- Increased risk of spoilage and dry matter loss
- Potential for overheating in storage
Harvest and Storage Management
Good silage management is especially important when storing drought-stressed corn because oxygen exposure remains one of the primary causes of feed quality losses. Recommended practices include:
- Harvesting promptly once target moisture is reached
- Chopping forage uniformly to facilitate packing
- Packing tightly to exclude oxygen
- Covering and sealing immediately with high-quality plastic
- Securing covers and sealing edges to prevent air infiltration
- Monitoring silage for heating during storage and feedout
Pricing Considerations
According to Dr. Bill Weiss and colleagues at Ohio State University, drought-stressed corn may reasonably be valued at approximately 85–90% of the economic value of normal corn silage when compared on an equivalent dry matter basis. However, because drought conditions can substantially affect forage quality, laboratory analysis of whole-plant samples should be used when establishing forage value.
Conclusion
Drought-stressed corn can represent a significant challenge for livestock producers, but it does not have to equate to a complete loss of forage value. While yield and grain development are often reduced, the remaining plant material can still provide a useful energy and fiber source when properly harvested and stored as silage.
Ultimately, drought-stressed corn should be viewed as a salvageable feed resource rather than a failure, provided it is managed with the same attention to detail as higher-yielding corn silage. With appropriate harvesting decisions and sound ensiling practices, producers can capture much of its remaining nutritive value and reduce the economic impact of drought conditions on feed supplies.
For additional considerations, see the companion article, Feeding Drought-Stressed Corn to Livestock.
Sources
Weiss, B., Shoemaker, D., and St-Pierre, N. n.d. Pricing Drought-Stressed and Immature Corn for Silage. Ohio Dairy Industry Resources.
