Options for wet corn, immature corn, and a challenging harvest
September 26, 2019
Bill Halfman & Ryan Sterry, Agriculture Agents, UW-Madison Division of Extension
Weather continues to be a challenge in St. Croix County and much of Northwest Wisconsin. Corn silage harvest has begun, but as has been the story of 2019, interrupted by rains. This year’s corn crop continues to be highly variable in maturity across the area. This variability in growth, and questionable weather, has left growers wondering if some fields will mature before a killing frost and if some will reach maturity but remain wet in the field. The following, adapted from Phil Durst at Michigan State Extension, explores some options to consider.
Start conversations now
Short forage supplies this year may make diverting wet corn to silage for livestock feed a viable option. This type of purchase can be a win-win. The buyer is adding to his or her forage or grain supply with good feed. The seller is getting a rescue of a crop that he or she cannot otherwise sell, or only after high drying costs and then at a discount. If the buyer is harvesting it, then the seller is also saving costs.
These conversations should happen as soon as possible. There are challenges in these agreements to determine pricing and yield in these unique situations. Corn killed by frost before maturity is expected to be lower in starch content, and lower in yield per acre. The ability to weigh loads, leave check strips, and submitting samples for feed quality analysis are highly important for both parties to determine what they are rally dealing with. Having a plan before harvest can provide peace of mind to both buyer and seller.
Options for Livestock Feed: High Moisture Corn
The maturity of the corn at the time it is killed by frost drives the options. Corn that is nearer to completion of starch deposit in the kernels (black layer) may be harvested as high moisture corn. Ideally, kernel moisture should be in the range of 28-32% for harvest as high moisture shelled corn for effective fermentation. A minimum of 26% moisture, and maximum of 36%, is recommended for high moisture corn storage in bunkers or bags, with slightly drier range of moistures for oxygen limiting tower silos.
Depending on the buyer, harvest equipment, and storage structure, high moisture shelled corn, high moisture ear corn, or snaplage are all viable options. In each case the price will be based on the current price of dry corn and adjusted based on percentage of corn grain and moisture. For reference, dry corn is standardized at 15.5% moisture. Adjustments should be made for wetter corn. The value of the crop can be calculated by adjusting for moisture compared to the local price for dry shelled corn. If the crop has not reached black layer, then there should be an adjustment for decreased energy content (quality).
Options for Livestock Feed: Corn Silage
But what if the grain does not reach maturity? Corn silage is still an option. It presents a challenge in valuing the product because it is farther in quality from dry grain, the basis of the price estimation.
Here is what we know about corn silage as it matures. The standard recommendation is to harvest corn for silage based on moisture at ½ milk line, or prior to black layer formation. As corn approaches this indicator yield per acre increases, starch content increases, and fiber content decreases as a percentage of dry matter. Digestibility increases as it approaches ½ milk line because a higher proportion of the plant is grain. Crude protein decreases as the plant matures.
The first consideration is to harvest corn at the right dry matter (32 – 38% DM) for optimal fermentation, regardless of maturity. When frosted, the leaves will quickly turn brown and the plant may appear dry, but the stalk holds the majority of the moisture, and it may be slower to dry down to harvest moisture. It is important to monitor whole plant moisture to determine harvest timing. Dry down in October is different than dry down in September due to day length and temperatures. Chopping higher may help slightly with corn that is closer to drying down into the desired moisture range, since the bottom of the stalk retains more moisture.
Whether planning to buy or sell standing corn for silage, yield per acre can be difficult to estimate. The best practice is to run loads across a scale and record the weights and number of loads. If scales are far from the fields, it may help to run some typical loads to the scales and then use the average weight from those times the number of loads delivered. Weight is a function of moisture content. Determining moisture is important for pricing. If price is determined based on 35% DM (65% moisture) and the material is 68% moisture, then price needs to be adjusted accordingly.
Silage Quality & Pricing
The feed value of corn is lowest between tasseling and milk stage. However; that does not necessarily make it “bad” feed. It just needs to be used accordingly. Feed not meeting the needs for a lactating dairy herd may still meet the nutrient requirements for replacement heifers or overwinter beef cattle in a properly balanced ration.
The other extreme we may encounter this fall is corn that dries down to moisture for silage harvest, but wet field conditions delay harvest. Once whole plant dry matter exceeds 40%, starch and fiber digestibility decreases, thus decreasing quality. Dry material also does not pack as well.
UW Extension has a nice spreadsheet tool and apps for both apple and android devices to determine prices for normal corn silage for a place to start determining a price. These pricing tools can be found at this web page: https://tinyurl.com/yxrfpwt5
For immature corn, we recommend adjusting the price down because of lower feed value; approximately 90% at early dent, 75-80% at soft dough stage. For example, CS harvested in the early dough stage – before dent – would be valued at $23.60 – $25.20 per ton (75-80% of normal CS price based on $3.50/bushel corn). These calculations and deductions are approximate and are used as examples for negotiations. It is important for people to use their own numbers.