Performance of cultural and mechanical practices on weed-control efficiency, productivity and economics of Indian mustard (Brassica juncea) under organic production

A field experiment was carried out during winter (rabi) season of 2017–18 and 2018–19 at the research farm of ICAR-Indian Institute of Farming Systems Research, Modipuram, Meerut, Uttar Pradesh, India, to study the effect of different weed-management practices on weed density, productivity and economics of Indian mustard under organic production. Eight cultural and mechanical weed-management practices, comprising hand-weeding, mechanical weeding, intercropping with chickpea (Cicer arietinum L.) (additive series), stale seedbed (SSB), reduced spacing, soil solarization using 25 μ transparent polythene sheet and mulching with different crop and weed residues area adopted. Among the different weed species, purple nut sedge (Cyperus rotundus L.) was dominant weed species and represented around 70% population of total weed density. At 20 days after sowing (DAS), the lowest weed density and the highest weed-control efficiency were found under soil solarization with 25 μ transparent polythene sheet + hand-weeding (HW) at 40 DAS, followed by SSB + reduced spacing (30 cm) + maize (Zea mays L.) straw mulching @ 5 t/ha + HW at 40 DAS treatment. An intercropping of Indian mustard with chickpea (1 : 1 additive series) also proved better for weed management with 6.8% weed-control efficiency as compared to the manual weeding. Yield attributes, viz. branches/plant (5.7), siliquae/plant (307), seeds/siliqua (14.6) and seed yield (3,527 kg/ha) were highest under application of Indian mustard oil cake @ 5 t/ha + HW at 40 DAS. The intercropping of Indian mustard + chickpea (1 : 1 additive series) improved the Indian mustard-equivalent yield by 92.0% as compared to 2 hand-weedings. The highest net returns (`125,194/ha) and benefit: cost ratio (B : C) (6.6) were recorded under intercropping with Indian mustard + chickpea (1 : 1 additive series). Therefore, intercropping of fast-growing crops with wide-spaced crop could be an efficient strategy for weed management and higher profitability under organic crop production.