Optimal Agricultural Practices for Growing Kenaf in Iowa.

Replacing petroleum-based materials with renewable materials is of critical importance as we transition to a vigorous bioeconomy. The use of natural fibers derived from plants like kenaf (Hibiscus cannabinus L.), an annual herbaceous multi-purpose fiber crop, represents one way to address the economic and environmental problems associated with the use of synthetics. Although kenaf is adapted to subtropical areas and can be grown in temperate areas where corn is adapted, very few kenaf studies have been conducted in the Midwest, especially in Iowa, where kenaf could be a promising crop, if properly grown. This study focused on investigating planting date, seeding density, row spacing, and nitrogen fertility effects on fiber quantity and quality of kenaf in Iowa. A first experiment was conducted in 2004, 2005 and 2006 and was planted in a randomized complete block with split plots in early May, late May and early June at 20, 38 and 76 cm-rows using 185328, 277993, 370657 seed/ha and 0 or 168 kg/ha of nitrogen. A similar experiment was performed in 2014 using this time two kenaf cultivars planted at 38 or 76 cm-rows at 247105 or 370657 seed/ha and receiving 0, 56, 112, 168 and 224 kg/ha of nitrogen. Yield, biweekly stem height and diameter, bast and core ratio and fiber composition were measured. The results show that it is better to plant kenaf in early or late May and that seeding rate and row spacing may be important considerations relative to kenaf end use because more crowded plants produce smaller stem diameters, richer in core fibers. Also, adding nitrogen was beneficial to kenaf but the response was year, season and variety dependent and could be used to manage crop composition. Overall, kenaf could be relatively easy to grow in Iowa and could bring diversity to its agriculture and industry.