According to the USDA, Wisconsin harvested 210,000 acres of winter wheat in 2015 and 250,000 acres of winter wheat in 2016. After harvest, some of these fields are planted with late-summer alfalfa and some receive manure, but many sit fallow for the rest of the growing season. Fields that are tilled late summer to control weeds are left vulnerable to erosion.
If farmers take action after harvesting wheat or other small grains, they can use the about 40% of growing season precipitation and Growing Degree Units (GDUs) that remain as of July 31. This 40% rule of thumb applies throughout the state of Wisconsin. Planting timing is important because 20% of annual GDUs accumulate in August. On average between the end of July to the end of October, Wisconsin receives 975 to 1,300 GDUs (corn base) and 9" to 11" of precipitation. This amount of heat and precipitation leaves the potential to grow more forage.
A strategy for building forage inventories is to raise double crop forages after small-grain harvest. Double crop forage is a sound strategy because of the need to store large forage inventories for winter. Rather than growing emergency forages to build inventory during weather-stressed years, planned double crop forage can increase the likelihood of success.
What double crop forage options are available?
A wide range of forage crops potentially can be planted after small-grain harvest. However, weather conditions will influence which forages will be more successful. Double crop forages such as brassicas, small grains, ryegrass, legumes, sorghums and millets, and even corn silage can be sources of late-season forage. Many studies have been conducted on emergency forages and fall small-grain forage. Yield results vary from 0.5 tons of dry matter per acre to 4 tons of dry matter per acre or more in Wisconsin.
Which double crop forages are most likely to perform well?
The most well understood double crop forage option is planting fall oats near Aug. 1. Research demonstrated oat variety selection is important for maximizing yield and quality. For example, Forage Plus oat is a good fit for yield and quality reasons because this variety should not develop into the boot stage as quickly as others, thereby allowing time to work around corn and soybean harvest. Earlier-maturing oat varieties can yield well, but forage quality may decrease as heading stage is reached. If fall planting is delayed, then earlier-maturing varieties should be considered. Adding peas to oats can increase protein by 3% to 5%.
On farms that use grazing, forage brassicas such as forage radish, turnip, kale or swedes have potential because they are fast growing and high quality. With recommended planting dates from mid-July to late August, timing of brassicas aligns well after small-grain harvest. Grazing brassicas can create unexpected livestock disorders such as bloat or nitrate poisoning. It is important to avoid abrupt changes from poor-quality pasture to brassicas and continue to supplement dry hay.
For more details about double-cropping forages: