Assessing Feasible Weed Management Options in Maize under Organic Farming System of Eastern Himalayas

Weed management under organic farming relies heavily on manual and mechanical methods, which are labour-intensive and costly, particularly in the high-rainfall hill ecosystems of North Eastern India. A field experiment was conducted for three consecutive years (2015–2017) on a long-term organic field (under organic management since 2005–06) at mid-altitude (950 m ASL) in Meghalaya to evaluate non-chemical weed management options for maize productivity, weed dynamics and soil health. Eight treatments were tested in a randomised block design, including hand weeding, mechanical weeding, soil solarization, mulching, stale seedbed preparation and maize–soybean intercropping. Among all treatments, two hand weedings at 20 and 45 days after sowing (DAS) recorded the lowest weed population (155.3/m²) and dry weight (75.3 g/m²) at 30 DAS. However, intercropping of maize with soybean (2:1) combined with one hand weeding at 45 DAS (T6) and stale seedbed + 25% reduced spacing + mulching with crop residues + one hand weeding at 45 DAS (T5) achieved significantly higher weed control efficiency at 60 DAS, the lowest weed indices (1.2 and 4.9%, respectively) and maize grain yields statistically at par with the weed-free check. T6 recorded the highest net returns (₹49,560/ha) and benefit–cost ratio (2.42), outperforming all other treatments, including the weed-free check, primarily due to lower weeding costs and the added benefit of biological nitrogen fixation by soybean. After three cropping cycles, T6 also recorded the highest soil organic carbon (22.3 g/kg), available nitrogen (272.5 kg/ha) and phosphorus (29.6 kg P₂O₅/ha), indicating concurrent improvement in soil health. Soil solarization performed poorly under the prevailing sub-32°C temperature regime of the region. Maize+soybean intercropping (2:1) with one hand weeding at 45 DAS is recommended as a practically viable, economically superior and soil health-enhancing weed management strategy for organic maize production in the North Eastern Hill Region of India.