Mint in Mississippi Nitrogen Fertilizer Study

Mint has shown a potential as an essential oil crop for the southeastern United States. ‘Native’ spearmint and ‘Arvensis II’ Japanese cornmint were grown in field studies conducted in 2011 and in 2012 at 2 locations in Mississippi: the North Mississippi Research and Extension Center at Verona and at Westside Farms, in Friars Point MS. The treatments were the nitrogen rates of 150, 200, 250, and 300 lbs N/ac at 2 locations. Dry weight, plant height, essential oil yield, and essential oil composition were analyzed. One half of the N (0–0–46) for each treatment was applied in early spring and the other half applied 7 days after the first harvest. Beds were formed with a standard 4-row bed-roller spaced 38 inches apart. Mint was transplanted (May 2011) in the field using a wagon wheel transplanter, with 1 ft. in-row plant spacing. Irrigation was used at both locations. Harvesting was done at initial flowering, representative samples were weighed immediately and air dried 5–7 days. Dried mint samples (8.82 oz. dried material), were steam distilled for 45 minutes for extraction of the essential oil. The average oil yield of ‘Arvensis II’ (52.4 lbs/oil per acre) was significantly greater than ‘Native’ spearmint (39.6 lbs/oil per acre) over both locations and harvest dates. Nitrogen rates had no effect on dry weight and plant height. Nitrogen had an effect on oil yields at Friars Point and on the concentration of carvone in ‘Native’ spearmint oil. ‘Arvensis II’ plants were taller (38.2 inches) than ‘Native’ spearmint plants (26.8 inches). The dry weight of the plants was greater at Verona (4,090 lbs/ac) compared to Friars Point (2,910 lbs/ac), and ‘Arvensis II’ provided greater dry weight (3,926 lbs/ac) than ‘Native’ spearmint (3,020 lbs/ac). The concentration of carvone in ‘Native’ spearmint oil was greater at Friars Point compared to Verona. The results suggest ‘Native’ spearmint and ‘Arvensis II’ Japanese cornmint can be viable crops for Mississippi and provide essential oil with desirable composition and yield.