Weed phyto–sociology, economic profitability and herbicidal residues as influenced by weed management and intercultural operations in turmeric (Curcuma longa L.)

Turmeric is a long-duration and widespread crop, so the presence of weeds in crops that appear late often creates an ideal environment for their growth. Therefore, to develop effective weed management, herbicide residue and harvest management in turmeric, a field experiment was conducted with twelve weed management practices, viz. metribuzin followed by (fb) hand weeding (HW) at 45 and 75 days after planting (DAP), metribuzin fb rice straw mulch fb HW at 75 DAP, pendimethalin fb two HW at 45 and 75 DAP, pendimethalin fb rice straw mulch fb HW at 75 DAP, atrazine fb two HW at 45 and 75 DAP, atrazine fb rice straw mulch fb HW at 75 days, oxyfluorfen fb two HW at 45 and 75 DAP, glyphosate fb two HW at 45 and 75 days, glyphosate fb two HW at 45 and 75 DAP, HW thrice at 25, 45 and 75 DAP, organic weed control (rice mulch) and un–weeded check was conducted at Typic Hapludalfs soil conditions of North Western Himalayas. Alternanthera philoxeroides comprised over 67 % of the total weed flora, followed by Ageratum conyzoides (16 %). Pre–emergence atrazine fb mulch fb HW resulted in increased mean fresh rhizome yield, gross returns and benefit cost ratio (BCR). The rise in yield due to harvesting during the second cropping cycle ranged from 59–221 %, gross returns from 63–230 %, net returns from 139–1300 % and BCR from 216–1874 %. After two years, the cultivation cost dropped by 23–29 %. However, herbicide residue estimation demonstrates that turmeric rhizomes and soil contain below detectable quantities of metribuzin, atrazine, pendimethalin, oxyfluorfen and metsulfuron–methyl, which do not hinder the quality of soil and produce. Using integrated weed management strategies, such as pendimethalin fb straw mulch fb HW, resulted in the most significant percent increase in net returns due to harvesting after two years and lower herbicidal residues compared to other weed management treatments.