Characteristics of menthol mint Mentha arvensis cultivated on industrial scale in the Indo-Gangetic plains

Abstract

Mentha arvensis L. (menthol mint) oil is the source of commercial natural menthol. This industrial crop is now cultivated in about 0.145 million ha in the Indian state of Uttar Pradesh (UP) and several other states encompassing Indo-Gangetic plains. Considerable variation has been reported in the yield and quality of oil obtained from the crops of menthol mint varieties Himalaya and Kosi taken in the area. A follow up study was made to ascertain the cause(s) of such variation in many villages of selected districts of UP. The soils sampled from the fields were studied for variability in reaction, salinity, organic carbon content, the contents of the major nutrients nitrogen, phosphorous and potassium and micro-nutrients manganese, iron, copper and zinc and crops of mint on the concerned fields were characterized for the herb, essential oil and menthol yields. The observations made in 69 farmers’ fields have indicated variation in soil characteristics, as well as herb, essential oil and menthol yields from the crops taken on them. However, herbs harvested from different fields did not differ much in their oil content. Imbalance in N, P and K supplements to the field was observed; it seemed to arise from unnecessary emphasis on urea application without concomitant K and P supplementation. The fields were particularly deficient in Mn among the micronutrients. There was need for heavier application of K, Cu, Zn, and Mn together with sufficient amount of N and P to obtain better oil yields. To increase oil yield was inferred as the best means to increase menthol production from the fields of Indo-Gangetic plains.