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© 2005 Plant Management Network.
Accepted for publication 3 August 2005. Published 13 September 2005.

Influence of Cultural Practices and Crop Rotation on Kenaf Yield in North Carolina

David L. Jordan, Associate Professor and Extension Agronomist, Department of Crop Science, Box 7620, North Carolina State University, Raleigh 27695; J. Steven Barnes, Tidewater Agricultural Research Station, 207 Research Station Road, Plymouth, NC 27962-9526; Clyde R. Bogle, Upper Coastal Plain Research Station, Rt. 2 Box 400, Rocky Mount, NC 27801-9276; Ty M. Marshall, Border Belt Tobacco Research Station, 86 Border Belt Dr., Whiteville, NC 28472-6828; Tommy Corbett, Peanut Belt Research Station, 112 Research Station Lane, Lewiston-Woodville, NC 27849-9552; Carl R. Crozier, Department of Soil Science, Vernon James Research and Extension Center, 207 Research Station Road, Plymouth, NC 27962-9526; Billy McLawhorn, Consultant, McLawhorn Crop Services, Cove City, NC 28523; and Loren Fisher, Assistant Professor and Extension Agronomist, Department of Crop Science, Box 7620, North Carolina State University, Raleigh 27695

Corresponding author: David L. Jordan. david_jordan@ncsu.edu

Jordan, D. L., Barnes, J. S., Bogle, C. R., Marshall, T. M., Corbett, T., Crozier, C. R., McLawhorn, B., and Fisher, L. 2005. Influence of cultural practices and crop rotation on kenaf yield in North Carolina. Online. Crop Management doi:10.1094/CM-2005-0913-01-RS.

Abstract

Kenaf is a relatively new crop to North Carolina and its impact on cropping systems has not been clearly determined. The impacts of crop rotation on kenaf, as well as the impacts of kenaf on rotation crops were examined. Crops preceding kenaf included corn, soybean, cotton, and peanut while crops following kenaf or corn included corn, soybean, cotton, peanut, and tobacco. Experiments were also conducted to define interactions among kenaf planting dates, row width/plant population systems, and cultivars. In one of two years, kenaf yield was lower when kenaf followed peanut or soybean compared to following cotton. Peanut and soybean yield were similar when following either corn and kenaf. However, corn and cotton yield was lower in one of two years when following corn compared to kenaf. Tobacco yield was similar when planted following either corn or kenaf. The interaction of planting date, row width/plant population, and cultivar was not significant for kenaf yield. No yield differences were observed between kenaf cultivars Everglade 41 and Tainung 2. Kenaf yield was higher when planted May 15 rather than June 15 and when kenaf was planted in rows spaced 8 inches apart (total plant population of 261,000 plants per acre) compared to rows spaced 36 inches apart (total plant population of 174,000 plants per acre).

Introduction

Kenaf (Hibiscus cannabinus L.) is a fiber crop grown in several regions of the world including the United States (9,10). Core and bast fibers have a variety of functions, although sustained markets have been difficult to establish (1,10). A processing facility designed specifically for kenaf was established in eastern North Carolina in 2002, and several thousand acres were planted in North Carolina during 2004 (1).

Kenaf has been grown in the Tidewater region of North Carolina on organic or peat soils with yield in the range of 13 to 18 tons/acre (3). Coastal Plains soils in eastern North Carolina differ from the Tidewater soils in parent material, topography, fertility, and water holding capacity as well as management issues such as nematode and hardpan development. Transportation of kenaf from the Tidewater region to the facility established in eastern North Carolina would be cost prohibitive. Information is limited in North Carolina comparing kenaf yield potential on sandy soils typical of the North Carolina Coastal Plain, and additional research is needed to determine how kenaf responds to a range of cultural practices in the region.

Rotation crops can have a major impact on pest development and yield of crops in the rotation. Crops that are susceptible to nematodes most likely will suffer if kenaf becomes a major component of the cropping system (5). Corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea L.), soybean [Glycine max (L.) Merr.], and tobacco (Nicotiana tabacum L.) are grown in the Coastal Plain of North Carolina, and these crops could be grown in rotation with kenaf. Research evaluating these rotation crops, especially peanut and tobacco, in rotation with kenaf is limited.

Previous cultivar trials in North Carolina were conducted on soils in the Tidewater region, but not on coarser-textured soils more typical of the North Carolina Coastal Plain soils near the kenaf processing facility. Planting patterns and planting date can influence kenaf yield (2,4,6,7,8). Dry matter production is generally higher when kenaf is planted earlier in the season and given a greater period of time to produce biomass (3,6).

Establishment of a potential market for kenaf combined with capital investment in a processing facility in North Carolina has lead to the need to understand cultural factors that influence kenaf on soils in close proximity to the kenaf processing facility. Therefore, research was conducted to compare kenaf and rotation crop yield in short-term cropping system experiments and to define interactions of planting date, planting pattern, and cultivar selection in North Carolina.

Evaluation of Cropping Systems

Experiments were initiated in North Carolina during 2002 at the Peanut Belt Research Station located near Lewiston-Woodville on a Norfolk sandy loam soil (fine-loamy, siliceous, thermic, Typic Paleudults) to evaluate the influence of corn, cotton, peanut, and soybean on yield of kenaf planted the following year. Additionally, corn and kenaf were followed by corn, cotton, peanut, and soybean. These two experiments were also repeated in an adjacent field beginning in 2003. Cultivars for cotton, kenaf, peanut, and soybean were Suregrow 105, Tainung 2, NC-V 11, and Asgrow 590, respectively. The corn hybrid was Pioneer 31G98. Plot size was eight rows (spaced 36 inches apart) wide by 50 ft long. All crops were planted between May 5 and May 20. Production and pest management practices for each crop were consistent with those recommended by the North Carolina Cooperative Extension Service for northeastern North Carolina on this soil series.

Experiments were also initiated in North Carolina during 2003 at the Border Belt Tobacco Research Station located near Whiteville and at the Upper Coastal Plain Research Station located near Rocky Mount to determine tobacco yield following corn and kenaf planted the previous year. Soil at Rocky Mount and Whiteville was a Norfolk sandy loam. Tobacco seeds were planted in the greenhouse and were later set in the field during late April using a transplanter. The tobacco cultivar K-346 was planted at Whiteville and the cultivar NC 71 was planted at Rocky Mount. The corn hybrid was Pioneer 3163 and the kenaf cultivar was Tainung 2 at both locations. Plot size was 24 ft wide by 50 ft long corresponding to eight rows spaced 36 inches apart for corn and kenaf or six rows spaced 48 inches apart for tobacco. Corn was planted in late April at both locations. Kenaf was planted in mid-May, and tobacco was transplanted in late April. Production and pest management practices for each crop were consistent with those recommended by the North Carolina Cooperative Extension Service for each region of the state.

The center four rows of each eight row plot for corn, cotton, peanut, and soybean were harvested using conventional harvesting equipment. The center two rows of each plot of tobacco were harvested by hand four times and tobacco was flue cured. A 10-ft section from the center of each plot of kenaf was harvested in mid-November and weighed in the field. Approximately five pounds of kenaf from each plot were also weighed in the field and then oven-dried to adjust wet weight of kenaf in the field to dry weight. Height of kenaf was determined from the ground to the top of three plants within the canopy in the experiments where kenaf was planted after rotational crops. Height was recorded in mid-July 2003 and late September 2004. Regardless of crop, all yields were converted to lb/acre at moistures appropriate for marketing. Prior to digging peanut, visual estimates of the percentage of the peanut canopy expressing symptoms of Cylindrocladium black rot [caused by Cylindrocladium crotolarie (Loos) Bell and Sobers] (%CBR) were determined using a scale of 0 to 100% where 0 = no visible symptoms and 100 = the complete canopy expressing visible symptoms of disease.

The experimental design was a randomized complete block with four replications in all experiments. Data for crop yield, %CBR, kenaf height, and visual estimates of the percentage of Cylindrocladium black rot were subjected to analysis of variance. Means were separated using Fisher’s Protected LSD test at P < 0.05.

Interactions of Planting Date, Row Pattern/Plant Population, and Cultivar

Planting date, row pattern/plant population, and cultivar impacts on kenaf yields were investigated in 2001 and 2002 at the Peanut Belt Research Station located near Lewiston-Woodville on a Norfolk sandy loam soil. Treatments consisted of a factorial arrangement of treatments with two levels of planting date (May 15 and June 15), two levels of row spacing/plant population (rows spaced 8 or 36 inches apart), and two levels of cultivar (Tainung 2 and Everglade 41). Plot size was 12 ft wide by 50 ft long. In-row plant population was 4 and 12 plants per ft for the 8- and 36-inch row spacings, respectively. These seeding rates corresponded to a final plant population of approximately 261,000 and 174,000 plants per acre for these respective row spacings. Kenaf was planted flat in conventionally-prepared seedbeds and was fertilized preplant with 0-0-60 (N-P₂O₅-K₂O) at 150 lb/acre. Trifluralin herbicide was incorporated at a rate of 1.0 lb ai/acre over the entire test area. One hundred lbs of N per acre was applied as ammonium nitrate to the soil surface approximately 4 weeks after planting. A section of each plot consisting of one row (36-inch row spacing) or 3 rows (8-inch row spacing) by 10 ft was cut at the ground level in mid-November and weighed. A sub-sample from each plot was also weighed in the field and oven-dried for conversion of wet weight to dry weight as described previously.

Data for kenaf yield was subjected to analysis of variance appropriate for the factorial arrangement of treatments. Means of significant main effects and interactions were separated using Fisher’s Protected LSD Test at P < 0.05.

Evaluation of Cropping Systems

There was no difference in kenaf height during either year regardless of preceding crop (data not shown). Kenaf yield did not differ when following corn, cotton, peanut, or soybean in 2003, with yields ranging from 9,130 to 10,330 lb/acre (Table 1). In contrast, kenaf yields following the leguminous crops peanut and soybean did not differ but were lower than yields following cotton during 2004 (Table 1). Kenaf yield following corn did not differ from kenaf yields in the other rotations. The causative agent for yield differences between crop rotations was not determined in this experiment. Additional research, especially with longer rotations, needs to be conducted to determine the nature of this response.

Table 1. Kenaf whole-plant yield when planted the year following corn,
cotton, peanut, or soybean.*

 * Means within a year followed by the same letter are not significantly
different according to Fisher’s Protected LSD test at P < 0.05.

There was no difference in peanut or soybean yield when following kenaf during either 2003 or 2004 (Table 2). In peanut, the percentage of diseased canopy did not differ when peanut was planted the year following corn or kenaf (data not shown). However, a numerical difference of 13 percentage points (18% following kenaf versus 31% following corn) was noted for disease incidence in 2003 (data not shown). Additionally, peanut yield was almost 1,000 lb/acre lower when peanut followed corn compared to kenaf, although the difference was not significant. However, in 2004 there was no difference in the percentage of disease (8% following both rotation crops) (data not shown) or peanut yield when comparing previous rotation crops (Table 2). No differences in corn or cotton yields were noted in 2003 when following corn or kenaf (Table 2). Yield of corn and cotton following corn was lower than when following kenaf in 2004 (Table 2).

Table 2. Corn grain, cotton lint, peanut weed, and soybean seed yield
when these crops were planted the year following corn or kenaf.*

 * Means within a year for each crop rotated with corn or kenaf followed
by the same letter are not significantly different according to Fisher's Protected LSD test at P < 0.05.

In two additional experiments, tobacco yield did not differ when following corn or kenaf. Tobacco yield at Rocky Mount was 3,190 and 2,970 lb/acre and at Whiteville was 3,630 and 3,620 lb/acre following corn and kenaf, respectively (data not shown).

Interactions of Planting Date, Row Spacing/Plant Population, and Cultivar

The interaction of planting date by row spacing/plant population by cultivar was not significant for kenaf yield in 2001 or 2002. Additionally, interactions of planting date by cultivar, planting date by row spacing/plant population, and row spacing/plant population by cultivar were not significant. While the main effect of cultivar was not significant in either year, main effects of planting date and row spacing/plant population were significant during both years (Table 3).

Table 3. Main effects of planting date, row spacing/plant population, and cultivar on kenaf yield.*

 * Means within a treatment factor for each year followed by the same letter are not significantly different according to Fisher's Protected LSD test at P < 0.05. Data for each main affect are pooled over levels of the other treatment factors for each year. Interactions of planting date by row spacing/plant population by cultivar as well as two-way interactions of these factors were not significant at P < 0.05.

When pooled over planting date and cultivar, kenaf yield was 2,440 and 2,870 lb/acre higher when planted May 15 rather than June 15 during 2001 and 2002, respectively (Table 3). Additionally, when kenaf was planted in rows spaced 8 inches apart (261,000 plants per acre) rather than 36 inches apart (174,000 plants per acre), yield was 1,870 lb/acre higher in 2001 and 2,570 lb/acre higher in 2002 (Table 3). A higher plant population per acre established in the narrow rows compared with a lower plant population established in the wider rows may have contributed to higher kenaf yields, and the yield response may not have been solely associated with differences in row spacing. However, the economic gains from increased yields would have to be compared to the increased seed costs before selecting a seeding rate. There was no difference in yield when comparing the cultivars Tainung 2 and Everglade 41 (Table 3), which was consistent with other research (2). Previous research (7) has shown inconsistent yield response to row spacing/plant population, although in some instances yield was higher when kenaf was planted in narrow rows at higher plant populations compared with planting in a wider row spacing at lower plant populations. Research also suggests that earlier planting often results in higher yields (4).

Summary

Collectively, these data demonstrate interactions occur in cropping systems, but are inconsistent. Kenaf yield was lower in one of two years when following peanut compared with cotton. Peanut and soybean yield was not affected when kenaf was the previous crop in either year while corn and cotton yield was higher following kenaf in one of two years. Tobacco yield did not differ when planted following corn or kenaf. These experiments were conducted in short-term rotations, and additional research is needed to determine the impact of kenaf incorporated into cropping systems for more than two years. These data also indicate that planting date and row spacing/plant population are more important variables than cultivar selection when kenaf is grown under the environmental and edaphic conditions existing in these experiments. Kenaf responded independently to row spacing/plant population and planting date. Planting in mid-May or in narrow rows resulted in the higher yields than planting or in wider rows in mid-June on sandy soils on the Coastal Plain of North Carolina.

Acknowledgments

This research was funded in part by the North Carolina Agricultural Foundation and Greene Natural Fibers, LLC. Appreciation is expressed to Andy Moe and Paul Skillicorn for support of this project. Dewayne Johnson, Louis Pitt, Joel Alston, and Barry Thompson provided technical assistance. Appreciation is expressed to Dr. Bill Fike for discussions relative to kenaf production and utilization in North Carolina.

Literature Cited

1. Burgess, C. 2004. Kenaf the versatile fiber crop can replace tobacco in eastern North Carolina. Carolina Country July:22-23.

2. Clark, L. J., and Carpenter, E. W. 1998. Kenaf varietal comparison at the Stafford Agricultural Center, 1998. Online. 1999 Forage and Grain Rep., Coll. Agric. Univ. Ariz. Tucson.

3. Fike, W. T. 1988. The rise and fall of kenaf as a fiber crop in North Carolina. Page 297-299 in: Proc. of the First National Symposium New Crops: Res. Development, Economic. Oct. 23-26, 1988. J. Janick and J. E. Simon, eds. Indianapolis, Ind.

4. Hovermale, C. H. 1994. Kenaf variety by date of planting in Mississippi. Pages 3-5 in: A Summary of Kenaf Production and Product Development Research 1989-1993. Miss. Agric. For. Exp. Sta. Bull. 1011. C. E. Goforth and M. J. Fuller, eds. Miss. State Univ.

5. Lawrence, G. W. 1994. Plant-parasitic nematodes – pest of kenaf. Pages 13-14 in: A Summary of Kenaf Production and Product Development Research 1989-1993. Miss. Agric. For. Exp. Sta. Bull. 1011. C. E. Goforth and M. J. Fuller, eds. Miss. State Univ.

6. Neill, S. W., Hovermale, C. H., and Kurtz, M. E. 1994. Fertility and row spacing for kenaf production. Pages 7-8 in: A Summary of Kenaf Production and Product Development Research 1989-1993. Miss. Agric. For. Exp. Sta. Bull. 1011. C. E. Goforth and M. J. Fuller, eds. Miss. State Univ.

7. Neill, S. W., and Kurtz, M. E. 1994. Agronomic research for kenaf crop production in Mississippi. Pages 1-2 in: A Summary of Kenaf Production and Product Development Research 1989-1993. Miss. Agric. For. Exp. Sta. Bull. 1011. C. E. Goforth and M. J. Fuller, eds. Miss. State Univ.

8. Neill, S. W., and Kurtz, M. E. 1994. The effect of plant population on kenaf yield. Page 6 in: A Summary of Kenaf Production and Product Development Research 1989-1993. Miss. Agric. For. Exp. Sta. Bull. 1011. C. E. Goforth and M. J. Fuller, eds. Miss. State Univ.

9. Taylor, C. S. 1993. Kenaf: An emerging new crop industry. Pages 406-407 in: New Crops. J. Janick and J.E. Simon, eds. New York, NY.

10. White, G. A., Cummins, D. G., Whiteley, E. L., Fike, W. T., Greig, J. K., Martin, J. A., Killinger, G. B., Higgins, J. J., and Clark, T. F. 1970. Cultural and harvesting methods for kenaf: An annual crop source for pulp in the southeast. ARS-USDA Prod. Res. Rep. No. 113. Washington, DC.