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Fike, W.T. 1990. The rise and fall of kenaf as a fiber crop in North Carolina. p. 297-299. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

The Rise and Fall of Kenaf as a Fiber Crop in North Carolina

William T. Fike

  1. INTRODUCTION
  2. ADAPTING KENAF TO NORTH CAROLINA
    1. Cultivar Evaluation
    2. Fertilization
    3. Date of Planting and Soil Preparation
    4. Seeding
    5. Herbicides
    6. Harvesting
  3. COMMERCIAL PRODUCTION OF KENAF
  4. KENAF—A NEW CROP?
  5. REFERENCES

INTRODUCTION

Kenaf (Hibiscus cannabinus L., Malvaceae) is presently grown in India and Thailand, where it is an important source of bast or cordage fibers used in the manufacture of rope, bagging and other coarse fiber products. Plants grown as annuals in North Carolina reach heights of 2.5 to 3.0 m, have stem diameters of 7 to 18 mm, and usually flower by the first of November. These flowers rarely produce seed under our environmental conditions. In Florida, plants will reach heights of 5.5 m. and have increased stem diameters. Kenaf is usually planted in 97 cm rows in Florida, but in North Carolina, kenaf is planted in 1&-36 cm rows with higher densities ranging from 803 to 927 thousand plants per ha. Yields of dry matter (about 13 to 18 tonnes/ha) are equal between the two locations.

Kenaf has been evaluated in North Carolina and the Southeastern United States since 1957 as an annual source of fiber for pulping (Wolff and Jones 1958, White et al. 1970, Taylor and Whitely 1981). Two types of fibers occur in the kenaf plant: bast fibers in the outer bark and short woody fibers in the thick core of pith. Both fibers can be used in making paper pulp. The kenaf would not substitute directly for wood in paper pulps but combinations of fibers from both sources could meet future demands for paper pulps in many areas of the United States. Greater yields of fiber per unit area can be obtained from kenaf than from our southern pine forests (Wolff 1964). Due to the vast forested areas in North Carolina, numerous tree farms, and the increased costs of pulping differing crops, we concluded that kenaf would never be grown by North Carolina farmers as a substitute fiber source for wood fiber. The kenaf bast fibers can, alternatively, be used alone or in combination with other fibers in the production of a fine quality paper product such as cigarette paper. Present sources of fibers for this product (i.e., seed flax straw) have been diminishing in recent years and a substitute fiber source could be beneficial to this industry.

ADAPTING KENAF TO NORTH CAROLINA

Kenaf has been evaluated in most areas of North Carolina. Highest yields (13 to 18 tonnes/ha) have consistently been obtained in Eastern North Carolina, the Tidewater region of the state, because of adequate moisture retention by its fertile soils. In addition, highly organic soils of this area have little, if any problems with rootknot nematode and hardpans, which are probably the most serious pests of kenaf.

Cultivar Evaluation

'Tainung l' and `Everglades 71' had been the leading cultivars in North Carolina production trials. Other cultivars grown in the Tropics for cordage ('Cuba 108', 'Cuba 2032', 'Guatamala 45' and 'Guatemala 51') had also been evaluated for North Carolina conditions. Quality seed of all kenaf cultivars were difficult to obtain. Most seed was obtained from El Salvador and performed adequately. A continued source of high quality seed of known purity was lacking. Initial seed increase fields were planted in Weslaco, Texas, but an early freeze destroyed the crop. An experimental planting was also made in Haiti and high quality seed was produced, but the long distance and poor communication were a problem. Experimental plantings for seed production were also successfully made in Burkina Faso by a local seedsman.

Fertilization

Kenaf grows well in soils that produce good yields of maize and soybean. Once the soils have been adequately limed and the phosphorus and potassium levels are in the medium to medium high range (soil-test index ranges are 0 to 25 = low, 26 to 50 = medium, and greater than 50 = high), an application of 135 kg of nitrogen, 29 kg of phosphorus and 56 kg of potassium per ha should be adequate for top yields of kenaf. The fertilizer should be applied broadcast at planting. The nitrogen rate can be reduced by 22 kg/ha if the soil tests over 4% organic matter, or if the kenaf follows soybeans. In one nitrogen test comparing 45, 67, 90,112,135 and 160 kg/ha of nitrogen, increasing increments of nitrogen fertilizer enhanced individual plant height, stem diameter, and plant yield (Sirichandhra 1981). In some trials yield per hectare was not improved with increasing increments of added nitrogen because of a decrease in plant stand due to increased competition between plants.

Date of Planting and Soil Preparation

Kenaf plantings did best when seeded into a warm soil, about May 20. However, plantings delayed after this date resulted in loss of yield. Seedbeds for kenaf should be smooth and firm before planting. Seed will germinate and plants emerge in just two days. Herbicides must be applied at planting to insure that emerging seedlings will not be sprayed and therefore killed or stunted.

Seeding

Highest kenaf yields in North Carolina were obtained when two 36 cm rows were planted on 97 cm beds. This row spacing was selected for ease of cultivation and for harvesting the crop with a forage chopper. In many cases, planting 3 rows per bed further increased yields because higher seeding rates could be used at planting. Dry matter yields increased proportionately with plant populations at all row spacings tested, (Zublena 1979). Another advantage of higher populations was that stalk diameter was minimized and yield of bast fiber increased from 36% bast fiber in a 1.52 cm stem to 44% bast fiber in a 0.66 cm stem (Sirichandhra 1981). Because of this increase in the percent of bast fibers at high populations, plus the added advantage of better weed control, commercial plantings in North Carolina were made in 18-cm drilled rows. Kenaf was seeded with a grain drill for a final plant stand of 700 to 900 thousand plants per ha in 18 cm rows. This requires a seeding rate of 16 to 20 seed per meter of row. Seeding rates varied with cultivar; 'Cuba 2032' required 27 kg per ha, while 'Tainung 1; because of larger seed, required 35 kg per ha.

Herbicides

Although kenaf grows rapidly and under ideal conditions could provide good weed control as it matures, control of early spring weeds is important. Trifluralin is not phytotoxic to kenaf and provided good weed control of grassy weeds and small seeded broadleafs (White et al. 1970). However, adequate weed control was not obtained when the organic matter content of the soil was greater than 4%. In those soils, propachlor (at 6.7 kg/ha) is recommended.

Harvesting

Plants defoliate following a frost and were harvested with a mower conditioner and windrowed. The windrows were flailed with a decorticator to separate the woody fiber from the bast fiber. The crop was then baled and stored in 12 x 30 x 9 m stacks until used. Date of harvest had a tremendous effect on dry matter yield per hectare. Most of our tests were harvested late and yields appeared low. The average yield for kenaf from an October 28 harvest was about 7 tonnes while the yield from the December 16 harvest was only about 5 tonnes. Dry matter yields of kenaf plants decreased with time. The soluble portions of the dry matter are leached from the plant while the fiber content decreases very little (Bagby et al. 1975). Lower yields from the later harvest would therefore provide equal amounts of bast fibers for pulping.

Plants remained green until December in two of the three years of commercial production. When harvest was delayed until January or later, wet soils made harvesting difficult. As farms were spread throughout three counties and harvesting was conducted by only one crew, many problems occurred. Additional mower-conditioners, balers, and pick-up equipment would be needed in the future for efficient timely harvest.

COMMERCIAL PRODUCTION OF KENAF

A North Carolina paper company was interested in contracting kenaf production in Eastern North Carolina, the Tidewater area of the state. In conjunction with the North Carolina Agricultural Extension Service, discussions were initiated with the Blackland Farm Managers Association and the Washington County Farmers Cooperative in October and December of 1976 and March of 1977. A total of 505 ha were contracted by 15 farmers for planting during the 1977 growing season. Plantings were also made on 404 ha in 1978 and 324 ha in 1979. The 24(c) registration labels for Ramrod 65W and Treflan EC were obtained by the Company for use as preemergence herbicides on kenaf. The Company took the soil test and fertilizer recommendations were made by the Soil Testing Division of the North Carolina Department of Agriculture. The following contract was initiated:

"Specifically, you agree to furnish ____ acres of land capable of producing good corn and soybean yields for the purpose of growing kenaf. In addition, you will agree to furnish and apply fertilizer as recommended by the North Carolina Agricultural Extension Service, based on soil tests that we will take on your fields. Such fertilizer is to be applied preplant or at the time of planting.

You further agree to seed the aforementioned acreage with kenaf seed that we will furnish. Such seeding shall be done with a grain drill at a rate of 25 pounds per acre (approximately 6-7 seeds per row foot). In addition, you will furnish and apply a recommended herbicide on the same day of planting. Such herbicides shall be applied in accordance with instructions from the North Carolina Agricultural Extension Service, including instructions as to the type of herbicide to be applied. You also agree to furnish and supply insecticides at such times and in such manner as may be recommended by the North Carolina Agricultural Extension Service.

It is further agreed that you will use all diligence and care possible in growing the kenaf in accordance with the provisions of this contract.

In return for the above services, we will pay you $225 per acre for all land which is actually used for the production of kenaf as above described, $125 per acre of such compensation to be paid at the time of planting, and the remaining $100 per acre to be paid when the kenaf is cut and harvested by us or by December 1, whichever is the earliest. We will also furnish necessary kenaf seed, will make a soil test of each field, will cut and bale the kenaf, and remove the baled kenaf from the field. We and the North Carolina Agricultural Extension Service will also instruct and recommend from time to time certain procedures, modifications, or applications which will assist in the growing of a crop which is suitable for the purposes intended"

KENAF—A NEW CROP?

Through the cooperation of industry, the USDA/ARS, NCSU Agricultural Research plus Extension Programs, it was predicted that kenaf production in future years could increase to as many as 4000 ha (10000 acres), and a new crop would be provided to North Carolina farmers. Unfortunately, the Company producing cigarette paper decided to eliminate their research efforts on kenaf and continued to use flax straw as its raw material for pulping. Although the venture failed, production information was obtained that may be used in the future. Farmers liked kenaf and appreciated the company's efforts in promoting the crop. They were treated fairly by the company and still hope that one day they will again grow kenaf.

REFERENCES

Last update March 10, 1997 by aw