Production of mint depending on organic manure at planting and dressing

This study aimed to evaluate the effects of organic fertilization at planting and dressing on the aboveground part dry biomass and on the content and yield of essential oil of mint (Mentha arvensis). The experiment consisted of two stages (harvests). A randomized complete block design was used, with three replications. At the first stage, five different cattle manure dosages (0, 2.5, 5.0, 7.5 and 10.0 kg m(-2)) applied to the plots at planting, were evaluated and the first harvest was carried out 120 days later. At the second stage after the first harvest, the plots were subdivided in four split-plot and four cattle manure dosages (0, 2.5, 5.0 and 7.5 kg m(-2)) were applied at dressing, following a split-plot design. The second harvest was carried out 120 days after the first one. The fresh biomass was dried in the oven at 37 degrees C and the essential oil was extracted in a Clevenger apparatus. Aboveground part dry biomass (g), essential oil content (w/w%) and essential oil yield were determined. The levels of cattle manure applied at planting and dressing affected in a positive linear way the aboveground part dry biomass production and the essential oil yield. Essential oil content was not affected by different organic manure levels.