9 MIN READ
Key Considerations for Selecting Silage Corn Products
February 11, 2021
Successful silage production depends on effective selection of corn products.
Corn products should be selected for high yield potential, relative maturity, and nutritional quality.
Herbicide and insect resistance traits are also important considerations for protecting and maximizing silage yield potential and quality.
Figure 1. Corn silage harvest in Depot, Connecticut.
Corn Silage Product Selection
Corn silage is an important source of forage in the United States, providing a high-quality feed crop for ruminant animals because of its relatively high energy content. Effective corn product selection is critical for a successful, profitable silage operation. Corn products should be selected for above average yield potential, appropriate maturity, and high nutritional quality, particularly high digestibility. Corn product selection should also take into consideration the availability of traits like herbicide and insect resistance. While conventional corn products may offer lower seed costs and market premiums, these products can require more intensive weed, insect, and other management practices, resulting in higher overall costs, lower stress tolerance, and lower yield potential.
Product Performance Information1,2
Corn product selection should begin with identifying products that have been tested locally and are adapted to local growing conditions for maturity, disease and insect resistance, and drought tolerance. Select corn products that show consistent performance over multiple locations under different soil and weather conditions. Look for product performance information from multiple sources, including universities, seed companies, and on-farm trials. Consider a package of several corn products to help spread harvest timing and potentially reduce agronomic risk.
Select for Yield Potential1-7
Later-maturing corn products often have higher silage yield potential. Select products that are 5 to 10 days later in relative maturity than those for grain. Later maturing products have the potential of producing 2 to 4 tons per acre yield over standard maturity products.3 Keep in mind that later-maturing corn products may not be suitable for harvesting grain in most years but may be suitable for high moisture corn, for early season silage production, or for use in areas where wet soils may impact harvest.
Selecting products with a range of relative maturities can widen the harvest window, allowing farmers to chop their corn at optimum moisture content. Harvesting at the best moisture level is critical to producing high quality corn silage. Selecting products with a range of maturity also expands the pollination window, reducing the risk that an entire crop suffers hot and dry conditions during pollination. Feed requirements, harvest timing, and the potential of wet soils at harvest may also impact corn product selection in terms of maturity.
Corn for silage can be planted at higher densities than corn for grain. Genetically modified (GM) corn products respond better to higher plant densities than conventional corn varieties and should be considered in product selection.4 Increasing plant populations by 10 to 20% over grain recommendations can help maximize silage yields. In University of Wisconsin research, maximum forage yield was measured at 44,000 plants/acre and 38,000 plants/acre for grain yield, while around 30,000 plants/acre was the minimum for maximizing grain and forage yield.5 Although population recommendations are generally higher for silage products, populations should not exceed the “upper end” recommendation for any corn product.
Select for Quality1-3,6,7
University and industry studies have shown that grain yield potential can help indicate high silage yield. However, high grain yield does not always mean high-quality silage. In silage product selection, it is essential to consider energy value in terms of high fiber and starch digestibility. When growers select silage products, they should determine what is needed to improve their current feeding ration (higher starch, improved fiber digestibility, or other factors). Forage analysis by a reputable laboratory and consultation with an animal nutritionist can also help determine the best silage corn for an operation.
MILK2006 Formula. The MILK2006 formula, developed by the University of Wisconsin, is one effective approach in determining the value of a silage corn product. The formula evaluates laboratory forage analysis and yield potential to create an index of potential milk production for silage products. MILK2006 calculates an estimate of milk/ton or the potential for milk production from one ton of silage. Combined with on-farm harvest data, this formula can also be used to estimate milk production/acre. For further information on the MILK2006 corn silage evaluation system, see:
https://fyi.extension.wisc.edu/forage/evaluating-corn-silage-quality-for-dairy-cattle/
Consider the Benefits of Herbicide Tolerance Traits
Weed competition reduces yield potential, digestibility, and protein content of silage.8 Corn is very sensitive to early season weed competition and loss of silage corn yield potential can begin soon after planting. The critical period of weed competition is variable. Roundup Ready® 2 Technology and tolerance to glufosinate when partnered with the use of a residual herbicide and multiple sites of action help provide broad spectrum weed season long control. Benefits include:
- Reduced plant stress due to weed infestations.
- Limited host plants for insects, diseases, and nematodes.
- Facilitates the use of reduced tillage for soil and water conservation.
- Corn products with Roundup Ready® 2 Technology contain in-plant tolerance to Roundup® brand glyphosate herbicides. This system provides proven crop safety, over-the-top application flexibility, and broad-spectrum weed control. Also, products with additional resistance to glufosinate can broaden the flexibility of the technology.
Consider the Benefits of Insect Resistance Traits
European corn borer, corn earworm, western bean cutworm, fall armyworm, and corn rootworm complex economic injury can cause stress and injury to plant tissues. This damage can reduce yield potential or allow plant pathogens entry points to infect, proliferate, and produce mycotoxins which have the potential to cause health problems in animals and humans.9,10,11 The insect protection in GM corn products protects the plant parts these insects feed on, which can help reduce the risks of lost yield potential and lower grain quality. Conversely, insecticide applications require precise application timing, rates, and coverage, and may affect non-target organisms such as pollinators and beneficial insects. Farmers planting corn products with insect protection traits can realize higher yield potential through:
- Harvesting higher quality grain by preventing insect damage that can lead to stalk and ear rot diseases, which in turn can reduce the occurrence of mycotoxins produced by fungal diseases in corn silage.
- Reduced plant stress from, ear-feeding insects, stalk-boring insects, and root injury from rootworms.12,13,14
- While European corn borer (ECB) populations are at historical lows, they still are a potential threat to non-Bacillus thuringiensis (Bt) corn products in some locations. An analysis of historical ECB damage in Minnesota estimated that Bt corn for ECB protection provided an average benefit of $17.24 per acre.15
- Corn rootworm protection in GM corn can have agronomic benefits in addition to insect management. Improved root growth and activity can allow plants to utilize nitrogen more effectively after flowering to promote higher kernel weight and yield potential.16
- Higher plant densities can improve silage yield potential in corn. Genetic improvements, including GM traits such as insect protection from the Bt gene, help support higher plant populations.17
GM products help protect yield potential for silage and provide other benefits. The PG Economics annual report on the impact of GM crops shows that GM crops are credited with decreasing pesticide and fuel use, facilitating conservation tillage practices that reduce soil erosion, improving carbon retention, and lowering greenhouse gas emissions.18
