Kenaf: making the news
Inky black hands after reading the morning newspaper may become a problem of the past with the development in the US of newsprint using kenaf fibre. With less yellowing, less ink rub off and significantly less energy to produce, kenaf is likely to be headline news early in the new millennium: 28 newspapers have made a commitment to use kenaf newsprint once a kenaf mill starts up in Texas later in 1999. The mill will be capable of supplying about 10% of the newspapers' annual consumption of newsprint and has environmental permits to allow its waste-water to be used to irrigate its kenaf fibre and seed crops.
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| credit: J Wesley Graham, MSU |
With concerns that there will be insufficient softwood in the future to supply increasing demand for pulp and paper products, kenaf (Hibiscus cannabinus L.) could provide a viable pulp alternative for many countries. It grows quickly, rising to heights of 12-18 feet within 6 months and annual yields of 5-10 tons of dry fibre/acre can be achieved. This is 3-5 times greater than the yield obtained from Southern pine trees that are currently used for pulp in the US, which can take from 7-40 years to reach harvestable size. In addition, kenaf is well suited to areas that currently grow cotton. Much of the kenaf production around the world is still grown and processed under labour intensive practices but research and development in the US has resulted in a completely mechanized approach to harvesting and processing kenaf. In southern Texas, kenaf has also proved itself more resistant to the effects of hurricanes and drought than other crops and, although fertilizer and water by irrigation can be applied to stimulate higher yields, there is little need for pesticides. However, kenaf is susceptible to root knot nematodes and cannot be grown in highly infested areas although improved tolerance of root knot nematodes has recently been achieved.
Kenaf can also be used as forage for animals, as in Africa where this crop originated and has been grown for thousands of years. Here the bast fibre has been used for cordage, the woody core of the stalks burned for fuel and the leaves consumed as a vegetable. More recent uses elsewhere for kenaf fibres range from soil-less potting mixes, animal bedding, fibreglass substitutes and insulation. Oil absorbent materials, such as Kenaf BIO-SORB, have also been developed from the woody core which are capable of absorbing and encapsulating up to twelve times its weight in oil. Developed at the Mississippi State University (MSU), Kenaf BIO-SORB is biodegradable due to the rich amounts of essential nutrients and high levels of micro-organisms contained within the material. It can be applied to oil-contaminated soils by raking or tilling or, because it floats, applied to oils spills on water and recovered for incinerating.
Through the research and development efforts of MSU and other research institutes in the US, the potential of kenaf for US farmers in southern states has increased dramatically over the last decade. Kenaf has been grown in more than eight states and more than 18,000 acres will be planted this year. The crop can be grown for its fibre and for its seed but, because of the onset of early frost in most regions of the US, the majority of kenaf seedpods never develop to maturity. Although this means that the plant cannot run wild and become a weed, consistent supply of seed can only be assured through seed companies who also grow the crop in Mexico.
Decreasing pulp supplies and the demand for alternative crops to replace tobacco and cotton in the US are likely to stimulate increasing interest in kenaf production in the States. However, with the wide range of kenaf products that can be achieved, those developing countries already growing kenaf, such as China, India and Thailand, may also attempt to increase production for pulping and other processes.
