Prospects of Kenaf as an Alternative Field Crop in Virginia

Kenaf (Hibiscus cannabinus L. ), a warm-season annual plant, has shown potential as an alternate source of fiber in the United States. Although preliminary research has indicated feasibility ofkenaf production in Virginia, production details are lacking. Field experiments were conducted during 1995 and 1996 to determine optimal row spacing and fertilizer needs, and to compare available kenaf cul ti vars. Although results indicated that differences in dry matter yields from four row spacings (30, 60, 90, and 120 cm) and four rates each ofN, P, and K fertilizers (50, 100, 150, and 200 kg·ha) were not statistically different, the yields were adequate ranging from 8.8 to 16.0 t·hawith an average yield of 12.5 t·ha-• Dry matter yields for narrow-leaf cultivars proved superior to broad-leaf, and the overall results demonstrate that kenaf can be easily produced in Virginia. INTRODUCTION Kenaf (Hibiscus cannabinus L. ), a relative of cotton ( Gossypium hirsutum L.) and okra (Abelmoschus esculentus L. ), is a warm-season annual plant that originated in northern Africa and has been used as a cordage crop for many years in India, Russia, and China (Dempsey, 1975). Kenafresearch in the USA began during World War II to supply cordage material for the war effort (Wilson et al, 1965). During the 1950s and early I 960s, it was determined that kenaf was an excellent cellulose fiber source for a large range of paper products ( newsprint, bond paper, corrugated liner board, etc.). It was also determined that pulping kenaf required less energy and chemical inputs for processing than standard wood sources (Nelson et al., 1962). More recent research and development work indicates that kenaf is also suitable for use in building materials (particle boards of various densities, thicknesses, with fire and insect resistance), absorbents, textiles, livestock feed, and fibers in new and recycled plastics (Webber and Bledsoe, 1993). These observations indicate that kenaf could be potentially grown in Virginia to diversify cropping systems, to provide alternative materials for paper mills, and to meet varied industrial needs. Virginia State University's New Crops Program, established in 1991, initiated a kenaf research project in 1992. The objectives of this project were 1 Contribution ofVirginia State University, Agricultural Research Station Journal Article Series No. 247. The use of trade names or vendors does not imply approval to the exclusion of other products or vendors that may also be suitable. 2 Corresponding Author, E-mail: hbhardwi @vsu.edu Virginia Journal of Science, Vol. 56, No. 3, 2005 http://digitalcommons.odu.edu/vjs/vol56/iss3 116 VIRGINIA JOURNAL OF SCIENCE to conduct preliminary production research and to determine the feasjbility of kenaf production in Virginia. Research conducted in Virginia during 1992-1994 indicated that kenaf has significant potential as an alternate crop in Virginia (Bhardwaj and Webber, 1994; Bhardwaj et al., 1995). However, information regarding desirable agronomic practices such as cultivar selection, fertility requirements, and plant densities, specifically for Virginia was not available. Therefore, experiments were conducted to identify: (1) high yielding varieties, (2) optimum levels of nitrogen, phosphorous, and potassium fertilizers, and (3) ideal row spacing. MATERIALS AND METHODS Three experiments were conducted during each of 1995 and 1996 at Randolph farm of Virginia State University, located in Ettrick, Virginia (37° 14' N Latitude and 77° 26' W Longitude) at an approximate elevation of 71 m. The soil type was an Abel sandy loam (fine loamy mixed thermic Aquatic Hapludult) soil that typically has a pH of 6.1 to 6.4. In the first experiment, four inter-row spacings (30, 60, 90, and 120 cm) were evaluated with two kenaf cultivars: "Everglades 41" (A kenaf variety with broad leaves) and "Everglades-71" (A kenaf variety with narrow leaves). Three replications of a split-plot design with varieties in main plots and row spacings in sub-plots were planted on May 22, 1995, and May 20, 1996. Each plot consisted of three rows with a 60 cm spacing between sub-plots. These plots received 100 kg · ha1 each ofnitrogen (N), phosphorous (P), and potassium (K). In the second experiment, four rates (50, 100, 150, and 200 kg·ha) each ofN, P, and K, were evaluated with Everglades 41 variety in four replications of a split-plot design with N in main plots, P in sub-plots, and Kin sub-sub-plots. Each plot consisted of three rows with inter-row spacing of75 cm with one row left blank between the plots. These experiments were planted on May 23, 1995, and May 20, 1996. In the third experiment, 21 kenaf cultivars were planted on May 23, 1995, and May 21, 1996, in a randomized complete block design with three replications. Each plot consisted of three rows with inter-row spacing of75 cm. These plots received 100 kg· ha-' each of nitrogen (N), phosphorous (P), and potassium (K). Approximately 100 seeds of each cultivar were planted in each 3 m long row. In each experiment, weeds were controlled with a pre-plant-incorporated application of 1.5 l· ha1 of trifluralin herbicide. These experiments were not irrigated. Data were recorded for dry matter yield and plant height from samples harvested manually at the ground level after a hard freeze in early January had effectively killed the plants. During 1995, a 1-m sample was taken from the middle row of each plot in each experiment; and in 1996, a 2-m sample was harvested. After a two-month storage period, meant to stabilize the moisture content to a constant value and to dry the material, the harvested material was measured and the yield calculated in t·ha-• All data were analyzed using General Linear Models procedure of SAS (SAS, 1996). RESULTS AND DISCUSSION Row-Spacing: The differences in dry matter yield, averaged across two cultivars, for the four row spacings were not significant (Table 1 ). However, the closer spacing of 30 cm between rows showed a numerically higher yield of 11.1 t·ha-• The dry matter yields of Everglades 41 (8.2 t·ha-) and Everglades 71 (8.6 t·ha-) were also KENAF PRODUCTION IN VIRGINIA 117 TABLE J. Effect of row-spacing on kenaf dry matter yield and plant height during 1995 and 1996 at