Yield improvement in the regenerated and transplanted mint Mentha arvensis by recycling the organic wastes and manures

Field experiments were carried out during winter-summer seasons of 1994 and 1995 at Lucknow, India, located at 26•5°N, 80•5°E and 120 m above mean sea level to study the effects of (i) organic wastes and/or manures on the regenerated and transplanted mint crops and (ii) rescheduling of the harvest time in the sucker-planted crop. The treatments studied were of citronella (Cymbopogon winterianus) distillation waste and pea (Pisum sativum) straw mulches at 7 t ha−1, farmyard manure (FYM) at 20 t ha−1 at planting, FYM at 20 t ha−1 after the first harvest and a control (no application of mulch and FYM), supplementary to the inorganic N fertilisation at 0, 80, 160 and 240 kg N ha−1. The harvesting times investigated in the sucker-planted crop were 90, 100, 110 and 120 days after planting. The use of citronella distillation waste as mulch and FYM were most effective in enhancing the total herb and essential oil yields (planted + regenerated harvests) when the planted crop was harvested at 110 days after planting. The yield of regenerated crop improved significantly in the plots that had received citronella mulch or FYM during the planted-crop period, as compared with that of the control; citronella-waste mulch treatment proved better than FYM treatment. Application of 160 kg N ha−1 in the form of inorganic fertiliser and citronella distillation waste mulch at 7 t ha−1 met the N requirements of the transplanted mint crop. Mulch applications improved the efficiency of utilisation of inorganic N by about 10%. Application of mulch had no effect on the quality of the oil obtained in the first harvest of the sucker-planted crop and in the transplanted crop. It is recommended that under subtropical conditions, citronella distillation waste mulch should be applied after the sprouting of suckers during the planted crop period to obtain higher yields of herb and essential oil from the planted as well as the regenerated crop harvests. In order to get the maximum yield advantages from both the harvests, the planted crop should be harvested at 110 days after planting. The use of citronella-waste mulch with 160 kg N ha−1 minimised the cost of transplanted mint production by a factor equivalent to one third.