Kenaf Productivity as Affected by Agricultural Practices in Iowa

Abstract

Development and commercialization of biobased and bioenergy products contribute to new and expanded markets for agricultural feedstocks, reduce U.S. dependence on petroleum, and diversify agriculture. In Iowa, there are opportunities for development of manufacturing products from biobased feedstocks and the production of kenaf (Hibiscus cannabinus L.), an annual, fast‐growing herbaceous crop. Different agronomic management practices from a single large field experiment were investigated for kenaf stem production in Iowa with the objectives to: (i) develop optimum agronomic practices (planting date, seeding rate, row spacing, N fertilization presence or absence) leading to optimal kenaf stem and fiber yield; (ii) assess the effects of crop management practices on kenaf morphology; and (iii) determine lignocellulosic composition of kenaf bast and core. Cultivar Tainung 2 was grown at Boone, IA, and measured at harvest for stem dry yield, stand density, stem height and diameter, core:bast ratio, and lignocellulose concentration. Results indicated that planting kenaf in early May in 20‐cm rows led to the greatest stem dry yields (13 Mg ha−1) and that 18.5 seed m−2 in 20‐cm was the optimal combination of practices for stem dry yield. Adding N was only favorable when kenaf was planted in early May. Crop management practices influenced stem height, diameter, and core:bast ratios; however, their effects on lignocellulose concentration in bast and core were nominal. It was concluded that kenaf responded well to Iowa's climate and that bast production could be improved by the selected agricultural practices.

Agricultural practices for growing kenaf in Iowa: II. Fiber composition and quality

“…Bourguignon et al. (2017) conducted a study in Iowa from 2004 to 2007, which investigated the influence of three row spacings, three seeding rates, three planting dates, and absence or presence of N fertilization. Nevertheless, several important knowledge gaps exist for producers interested in growing kenaf in the Midwest.…”

“…In Bourguignon et al. (2017), the N treatments only included absence or presence of N fertilization (0 or 168 kg N ha −1 ). Other investigations in the United States have reported kenaf response to N fertilization, with some studies showing N fertilization improved stem, cellulose, and lignin yield (Adamson, Long, & Bagby, 1979), while others reported little or no influence on yield from N fertilizer application (Massey, 1974; Webber, 1996; Danalatos & Archontoulis, 2010).…”

“…Bourguignon et al. (2017) used a single variety, Tainung 2. This cultivar was shown to be promising in Iowa (Bourguignon et al., 2016a) and it is one of the most commercialized cultivars in the world; however, ‘Whitten,’ a variety developed by Mississippi State University (Baldwin, Hollowell, Mosley, & Cossar, 2006), also showed good potential in Iowa.…”

“…Additionally, Bourguignon et al. (2017) only reported stem height and diameter at the final harvest and, therefore, did not give any indication about plant growth over the growing season. It was shown that plant height, harvested at a certain date after planting, was consistent and significantly higher than previous dates (Ogbonnaya, Nwalozie, Roy‐Macauley, & Annerose, 1998; Webber et al., 2002), and was sensitive to management practices, when grown in Greece (Danalatos & Archontoulis, 2010).…”

“…Although Bourguignon et al. (2017) reported the lignocellulose concentration in kenaf, the quantity of ash found in the dry bast and core material was not investigated. Ash concentration has been shown to be important for feedstock conversion into biofuel, because the ash presence can lead to fouling, corrosion, and erosion problems in the conversion processes (Mohan, Pittman, & Steele, 2006).…”