Farmers and ranchers know kochia plants, either as weeds, emergency forage, or both. Two species of kochia commonly grow in the United States and while they differ significantly, they can be confused with each other.
Kochia prostrata, also known as forage kochia, is a perennial, broadleaf plant that grows well in a variety of environments. Although it is a non-native plant of Asian origin, K.prostrata is not considered an invasive weed.
Kochia scoparia, also known as fireweed, burning bush or summer cypress, is an annual plant that spreads more readily and becomes a problem weed in some areas. This website has photos comparing the two plants at different growth stages.
Researchers with USDA’s Agricultural Research Service, running field trials with K. prostrata in Utah, have found the plant can provide more nutritious winter forage than traditional rangeland vegetation. They found that the forage yield on rangelands seeded with forage kochia was 2,309 pounds per acre, six times greater than the forage yield on traditional grazing lands in the same area. In their trials, rangelands with forage kochia could support 1.38 animals per acre, while the traditional rangelands could support only 0.24 animals per acre. The forage kochia in these trials supplied a crude protein content of 11.7 percent, compared with just 3.1 percent crude protein in stockpiled grasses on similar rangeland.
Forage kochia typically grows one- to two-feet tall on western rangeland, but according to an earlier report, ARS scientists are working to develop taller varieties, which could provide more accessible winter forage for cattle in snowy environments.
Forage kochia is known to be drought tolerant, and the ARS researchers note it can establish on damaged rangeland and withstands wildfires. According to a report from Utah State University, forage kochia suppresses or eliminates the invasion of alien annual weeds such as cheatgrass, halogeton, Russian thistle, and medusahead rye. It is not highly invasive, does not spread aggressively into healthy plant communities and does not compete well with perennial grasses.
The other species, Kochia scoparia also has forage value, particularly in its early growth stages, and has served as emergency feed for cattle in drought areas. According to a report from Purdue University, protein content in K. scoparia ranges from 11 to 22 percent, and decreases as the plant matures. When cut at the recommended stage, kochia hay contains up to 60 percent leaves, has good aroma and palatability better than that of grasses, such as bromegrass, but a little lower than that of alfalfa. Oxalate levels for K. scoparia range from 6 to 9 percent. Feeding calcium phosphate and other kinds of feed, such as alfalfa, tends to reduce oxalate toxicity. Animals with symptoms of oxalate toxicity should be removed from kochia immediately.