Effect of irrigation and fertility levels on yield, quality and economics of Japanese mint (Mentha arvensis) under drip irrigation system

An experiment was conducted during rabi seasons of 2005–06 and 2006–07 to study the effect of fertigation on yield and net return of Japanese mint (Mentha arvensis L.). The treatments consisted of three irrigation regimes (I1–drip irrigation at 100%, I2– at 80% and I3– at 60% Pan Evaporation) and three fertility levels (F1– 100%, F2 – 75% and F3 – 50% of recommended dose of NPK) with an extra (control) treatment having surface irrigation and soil application of fertilizer. The soil was acidic in reaction and sandy clay loam in texture. It was low in organic carbon (0.46%), available N, medium in available P and K. Fertigation produced maximum herbage yield of 32.0 t/ha and oil yield of 236 kg/ha, which was 16% and 17% more than the surface irrigation. It gave higher net return of 60,666/ha than the latter. Irrigating the crop at 100% PE with 100% RD produced highest herb (32.0 t/ha) and oil yield (260 kg/ha), net return ( 66, 480/ha) and benefit-cost ratio (1.88) as compared to other combinations of irrigation and fertility levels. The menthone content in the oil was doubled (9.33%), Isomenthone, Neomenthol and menthol contents were reduced while limonene and menthyl acetate contents were increased under fertigation.