Effect of irrigation, mulch and nitrogen on yield and composition of Japanese mint (Mentha arvensis L subsp haplocalyx var piperascens) oil

Effects of irrigation, mulch and nitrogen on yield and composition of Japanese mint (Mentha arvensis L. subsp. haplocalyx Briq. var piperascens) oil were studied using a replicated experiment. Two harvests were obtained 120 days after planting and 75 days after the first harvest. Significantly higher dry matter and essential oil yields were obtained with frequent irrigations (50 mm Cumulative Pan Evaporation), application of mulch and Nitrogen. The economic optimum rate of N was 215 Kg ha(-1). The essential oil from the first harvest was richer in menthol (78.8 %) than the oil obtained from second harvest (75.2 %). Soil moisture extraction was maximum between 15 and 30 cm soil depths. Consumptive use, water use efficiency and moisture use rare were maximum under higher irrigation levels and mulch application which reflect that more availability of moisture in soil profile with frequent irrigations and application of mulch.