Kenaf & milkweed: new fiber crops - U.S. Dept. of Agriculture, Economic Research Service report

Agricultural Outlook, August, 1991

Farmers, rural business, and policymakers are looking to alternative crops to diversify U.S. agriculture. Industrial crops-those used as inputs in manufacturing-are receiving some of this attention. Kenaf and milkweed are two that have potential to become major fiber crops, providing additional income for farmers, jobs for rural communities, and products for a wide range of uses.

Kenaf Acreage Contracted

For Commercial Use

Kenaf (pictured above) is a herbaceous annual grown in many tropical and sub-tropical countries as a substitute for jute in making twine, rope, and other cordage products.

Plants range in height from 12 to 18 feet, Leaves are either palmate or whole, depending upon the variety. Stems consist of an outer bark composed of bast (woody) fibers and an inner core containing shorter fibers. The longer bast fibers make up about 30 to 40 percent of the stem, on a dry-weight basis, and the shorter core fibers make up the remainder.

Until recently, kenaf was grown in the U.S. only for research purposes, primarily in Texas, Mississippi, and Oklahoma. This spring, however, a commercial firm - Natural Fibers of Louisiana, Inc. - contracted with farmers to plant 1,000 acres of kenaf in Louisiana.

Standard farm equipment can be used for planting and cultivation. Harvesting occurs during the fall, and the method varies depending on location and intended use of the fiber. The acreage in Louisiana will be harvested with a sugarcane harvester, and the stems will be field dried and stored on the farm for periodic retrieval by the processor.

In Texas, a prototype harvester has been developed that cuts the stems and lays them in rows. After 10 to 14 days of field drying, the stems will be gathered and shredded to be used for paper pulp.

In Mississippi, the weather at harvest time is a major variable. Field drying is not an option because heavy rains can coincide with the harvest. Researchers expect that a desiccant, or drying agent, will need to be applied before harvest.

Natural Fibers of Louisiana, Inc. is building a fiber separation plant near Jeanerette, Louisiana, to process the kenaf stems into bast and core fibers. The bast fibers have many uses, including fiberboard, molded car parts, acoustic tiles, carpet, padding, burlap, and fibers mats. The primary use of the core fibers will be poultry litter.

Kenaf To Yield

Improved Newsprint

A kenaf-based newsprint mill is planted for south Texas, to be located in the Rio Grande Valley near Raymondville, Construction is expected to begin later this year and be completed in 1992.

Farmers in surrounding countries will grow the 4,500 acres of kenaf needed to keep the mill running. Yields are expected to be about 6-8 tons per acre. When operational, the mill will produce 30,000 tons of newsprint annually.

Kenaf offers several advantages over conventional newsprint. It has excellent strength, better ink adherence (requiring less ink), and reduced ink runoff, and it provides sharper photo reproduction. Kenaf also requires less energy for pulping and brightens more easily than wood chips. Furthermore, it can be blended with recycled newsprint to improve paper quality.

Kenaf also has potential as forage for cattle and sheep. Crude protein content is between 15 and 22 percent depending on the part of the plant used, with leaves higher in protein than stems. If the crop is grown for forage only, farmers can get two cuttings per growing season. If the stems are harvested for fiber, the upper 2 to 3 feet of the plants can be ground and used as a feed ingredient.

Low Yields Slow

Milkweed Development

Two milkweed species, common and showy milkweed, are being grown in Nebraska for their floss. The floss, the plants' natural medium of seed dispersal, interests entreprenuers and scientists for use in insulated clothing, nonwoven textiles, and tissue paper.

During World War II, milkweed floss was substituted for kapok in life jackets. In the 1970's. the Department of Energy, Standard Oil of Ohio, and other establishments conducted research on the milky latex of the plant as an energy. source. When research was discontinued, an individual at Standard Oil saw greater market potential in the floss than the latex. As a result, Natural Fibers Corporation (no connection with Natural) Fibers of Louisiana, Inc.) was formed to study and commercialized milkweed floss.

Milkweed has been produced in Nebraska for 4 years as part of the company's experiments, with approximately 160 acres being grown this year. The plant is a perennial; commercial stands should last 5 to 10 years. About 20 inches of water are needed annually to maintain plant populations and promote pod formation.

Low yield is the major factor holding back the development of milkweed as a commercial crop. Yields in research plots during the last 5 years have averaged about 400 pounds of floss per acre, but those results have not have duplicated under field conditions.

Weeds, such as nightshade and foxtail, and diseases, such as black leaf spot and bacterial blight, have been major problems. In 1990, the average commercial yield was only 6 pounds of floss per acre, but that was double the 1989 average. The best field produced 28 pounds per acre, almost triple the highest yield in 1989. Half the fields in 1990 had no yield at all.