Consider Adding Deer-resistant Forages to Your Cropping Plan
Corn silage is one of the most common forages fed to livestock in Pennsylvania, and with good reason. Proper management and variety selection can offer high yields of a high-quality forage that easily meets the nutritional needs of some of our highest-producing livestock. However, these traits are also highly attractive to wildlife. Deer feeding damage makes up a significant portion of yield loss in cornfields throughout Pennsylvania. This article explores several options for alternative forages that can fit well in your production system while providing less temptation to those pesky deer.
Variety Selection
Both annual and perennial forages can supply adequate yield and forage quality to replace corn silage acres. When selecting perennial forages, it is important to note that deer graze some species selectively over others. In fields with heavy deer pressure, it would be best to avoid seeding legumes like alfalfa and clover, as these species will be selectively grazed over grass species.
Several annual forage crops can help to take the place of corn silage in the cropping system on acres heavily damaged by deer. Forage sorghum, sudangrass, and millets can provide significant yields with a demonstrated reduction in deer feeding and damage. Forage sorghum silage most closely matches the yield and nutritional value of corn silage with significantly less deer feeding. The yield of digestible nutrients of properly managed sorghum silage is approximately 92% that of corn silage, and the feeding value is estimated at approximately 85% that of corn silage.
Management Considerations
Establishment
Forage sorghum should be planted between 1 and 1.5" deep once soil temperatures reach 65°F. This often occurs approximately 2 weeks after the ideal planting date for corn in your area. A seeding rate between 5-8 lb/acre should result in an adequate stand. A routine soil test will provide soil fertility recommendations, but an estimate of 150 lb N, 75 lb P and 75 lb K can be used in the absence of soil fertility recommendations.
Pest Management
Forage sorghum suffers from few insect pests in Pennsylvania, so the routine use of insecticides is not recommended. It can be more sensitive to some herbicides used in corn production, so control of challenging weed species may be more difficult. A weed management program should start with adequate burndown (either with tillage, herbicides, or a combination). With adequate fertility and seeding rates, forage sorghum often emerges quickly enough to outcompete weeds, so a later herbicide application is not often necessary. In the case of late-season weed pressure, Table 2.6-16 in the Penn State Agronomy Guide lists some products available for use in summer annual grass crops.
Harvest Management
Harvest management starts with the maturity selection at planting. In shorter-season areas of Pennsylvania, it is important to select a hybrid with an earlier maturity so that it reaches the proper moisture content prior to frost. Forage sorghum, as well as many of the other annuals mentioned above, can accumulate prussic acid after a frost, so it is ideal to harvest prior to frost to avoid quality degradation and animal toxicity concerns. Sorghum maturity is rated as full, medium, and early, and your seed dealer can often help you select which maturity is the best fit for your growing conditions.
Forage sorghum should be harvested for silage when the grain is the soft to medium dough stage. At this stage, whole-plant moisture is most likely to be in the proper range for safe ensiling and fermentation.
Forage Utilization
Yield and forage quality of forage sorghum is comparable to corn silage and can even exceed that of corn silage in drought fields or those with heavy deer pressure. Additionally, forage sorghum can be established for a fraction of the cost of corn silage, decreasing the financial risk of crop establishment. Forage sorghum can be grown in mixtures with corn silage or as a barrier around cornfields to mitigate deer feeding pressure.
