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Alternative Field Crops Manual


D.J. Undersander1, B.R. Durgan2, A.R. Kaminski1, J.D. Doll1, G.L. Worf1, E.E. Schulte1

1Departments of Agronomy, Plant Pathology, and Soils, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin- Madison, WI 53706.
2Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108. September, 1990.

I. History:

Kochia (Kochia scoparia (L.) Roth), also known as fireweed, burning bush or summer cypress, was introduced to the United States around 1900 as an ornamental from Eurasia. Gardeners like this annual plant for its bright red foliage in autumn.

Farmers in dry areas, including the Southwest, have grown kochia as a drought-resistant forage crop on lands where other crops are difficult to grow -- hence the nickname "poor man's alfalfa." Because of kochia's low water requirements and resistance to diseases and insects, interest in it as a forage crop has increased in the last decade. Researchers at South Dakota State College have selected seeds from wild plants and produced satisfactory yields of leafy foliage.

Kochia, with its high protein content, requires relatively large amounts of nitrogen (100 to 250 lb/acre). If too much nitrogen is applied at once, however, toxic levels of nitrate may accumulate in the plants. Oxalate toxicity, which causes rough hair, humpback, jaundice, photosensitization and a stiff gait in livestock, is another potential problem for cattle that graze only on kochia for periods of 90 to 120 days.

Kochia grows wild throughout most of the northern half of the United States, except for parts of the Pacific Northwest. The plant has become a serious drought-resistant weed in the Plains states. Because of the wide genetic variability in wild kochia, it is possible that the problems associated with the plant as a forage crop can be overcome with plant breeding.

II. Uses:

Kochia is grown as a forage crop for sheep and cattle and as an ornamental. As a forage crop its feed value is slightly lower than that of alfalfa. Protein content ranges from 11 to 22%, and decreases as the plant matures. When cut at the recommended stage, kochia hay contains up to 60% leaves and has good aroma. Palatability of kochia is better than that of grasses, such as bromegrass, but a little lower than that of alfalfa. No objectionable milk flavor results from feeding kochia hay.

Oxalate levels for kochia range from 6 to 9%. 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.

Kochia can be used in revegetation programs for erosion control. It will germinate and grow at any time in the growing season, and it thrives in sandy, alkaline and other poor soils. Kochia can be sown by airplane on large areas that need revegetation, such as areas that have been devastated by fire. It provides a quick groundcover to protect topsoil and provide a food source for wildlife until native grasses take over.

III. Growth Habits:

Kochia is an annual forb that reproduces by seed. The bushy plants grow 1 to 7 ft tall and have taproots. The erect, striated stems are light green and much branched. The many alternate leaves are hairy, 1 to 2 in. long, narrow, pointed and attached directly to the stems. Small, green flowers and seeds are produced in narrow heads at the leaf axils. The plant is dark green when young and turns red as it matures. The seeds, when mature, are rough, flat, triangular and grayish-black in color. In the fall, the plants often break away from the roots and tumble over the ground, scattering the seeds.

IV. Environment Requirements:

A. Climate:

Kochia grows wild throughout much of the country, including the Upper Midwest. It can produce forage with as little as 6 in. of annual rainfall and is relatively cold hardy. It can be planted when soil temperatures are as low as 50°F.

B. Soil:

Kochia is grown on dry pastures, rangelands and cropland with alkaline soils. It will grow on land where other crops will not. Wild kochia has not spread to areas with very acid soils, and it is not known how well kochia would perform in such soils.

C. Seed Preparation and Germination:

The seed needs no treatment prior to planting. A properly managed kochia field will reseed itself. Grazed plants appear to produce more seed than the ungrazed ones, providing there is enough plant remaining at normal seeding time to provide seed shoots.

V. Cultural Practices:

A. Seedbed Preparation:

For best results, the soil should be plowed or disked to provide a firm, even and relatively weed-free seedbed. Nitrogen at 50 to 100 lb/acre should be applied prior to planting.

B. Seeding Date:

Kochia should be seeded as early as the soil temperature reaches 50°F (late April to early May) and anytime thereafter throughout the growing season.

C. Method and Rate of Seeding:

Seeding rates vary from 1 to 4 lb/acre, depending on the seeding method. Drilling as little as 1 lb/acre in 36 in. rows with a standard drill will result in a good stand; broadcast or airplane seeding requires more seed.

Though kochia seed does not need to be incorporated, research conducted in New Mexico indicates that a 1/4 in. seeding depth results in best emergence. Emergence is poor when seed is planted 3/4 in. deep or deeper.

Most kochia stands need thinning to prevent the crop from crowding itself out, particularly if a volunteer crop emerges the second year. The crop can be thinned to 2 to 10 plants/ft of row by chiseling at right angles or windrowing portions of the field and letting livestock clean up the dry feed as they graze the green material. Another method is to let cattle graze the kochia field for a short time when the plants are only 2 in. high.

D. Fertility and Lime Requirements:

Kochia is well adapted to alkaline soils, but it is not known how well it does on acid soils. Therefore, lime to a pH of 6.0; or try liming to different pH levels and observe the performance at each.

Because kochia is not a legume, nitrogen needs to be applied in proportion to the amount removed. This amounts to 40 to 60 lb N/ton of hay removed, or 100 to 250 lb N/acre. Do not apply more than 150 lb N/acre in one application, or nitrate toxicity can result. Apply 50 to 100 lb/acre prior to planting, and topdress the remainder later in the season based on anticipated yield.

Kochia responds very little to phosphorus and is low in this element. Cattle grazing on kochia should be fed supplemental phosphorus. Under conditions of adequate moisture, high phosphorus, zinc and boron levels suppress yield. The use of manure to supply nitrogen will likely result in excess phosphorus. Because the potash requirements of kochia are not known, adjust soil K to a medium level. Experiment with additional potash to find a rate suitable for your growing conditions. Suggested rates are 24 to 50 lb K2O/ton of hay harvested.

E. Variety Selection:

Though there is wide genetic variability in wild kochia, no improved varieties have been developed.

F. Weed Control:

Kochia does not compete well with grasses. This will be a major limitation to use in the Upper Midwest. It is best to plant kochia on a relatively weed-free seedbed with no quackgrass or other grassy weed history. There are no herbicides registered for use in kochia.

Volunteer kochia will be a problem in crops following kochia, thus cultural or chemical control of kochia will be needed in these crops.

G. Diseases and Their Control:

Kochia appears to be free of diseases that cause commercial loss.

H. Insects and Other Predators and Their Control:

Kochia is relatively unharmed by grasshoppers. No information is available on other predators.

I. Harvesting:

1. For pasture: To prevent oxalate toxicity, livestock should not graze on only kochia for more than 90 to 120 days. Rotational grazing of other crops will prevent oxalate poisoning. In contrast to perennials, the entire kochia plant can be eaten.

2. For hay or silage: Kochia should be cut for hay or silage when it is 18 to 26 in. tall and before it has produced seed. In the Southwest, three or four cuttings are possible in a growing season if live branches are left on the stubble each time.

If the kochia crop is thin, it can be cut with a mower with a windrower attachment. Thick stands should be windrowed with a side-delivery rake. The hay can be cured in the windrow or in shocks.

3. For seed: Seed can be harvested using a combine.

J. Drying and Storage:

It may take up to one day longer to field cure kochia hay than it does for alfalfa hay. Because kochia plants are hairy, the cured forage has a gray color which may resemble mold or spoilage. Hay can be stored in stacks or bales.

VI. Yield Potential and Performance Results:

Kochia produces hay yields of 1 to 4 ton/acre (dry matter) and seed yields of 1,500 to 2,000 lb/acre.

VII. Economics of Production and Markets:

Kochia is relatively inexpensive to produce and well adapted for use on dry or low fertility land. Markets for seed are few in number and may be difficult to identify.

VIII. Information Sources:

References to seed dealers and pesticide products in this publication are for your convenience and are not an endorsement of one product over other similar products. You are responsible for using pesticides according to the manufacturer's current label directions. Follow directions exactly to protect people and the environment from pesticide exposure. Failure to do so violates the law.