International Journal of Environment and Climate Change

Background: Grain legumes are an important and affordable source of dietary protein in vegetarian diets and help combat malnutrition. Vigna mungo (urdbean) is widely grown in India but is highly susceptible to weed competition, which can cause significant yield losses. Therefore, effective and cost-efficient weed management is essential, especially in organic farming systems.

Aims: The present study was undertaken to assess the effectiveness of various organic weed management regimes in reducing weed density and biomass in urdbean. It further aims to examine the impact of these practices on soil nutrient availability, particularly nitrogen (N), phosphorus (P), and potassium (K), during different stages of crop growth. The study also seeks to determine the nutrient concentration and total nutrient uptake by urdbean under different organic weed control treatments.

Study Design: The experiment was laid out in a Randomized Complete Block Design (RCBD) with twelve treatments and three replications.

Place and Duration of Study: Research Institute of Organic Farming (RIOF) field unit, University of Agricultural Sciences, GKVK, Bengaluru during Rabi season of 2025.

Methodology: The experiment is having twelve treatments viz., T₁: Inter cultivation at 25 DAS+1 hand weeding at 45 DAS, T₂: Stale seed bed technique + inter cultivation twice at 25 & 45 DAS, T₃: Straw mulching 5 t ha^-1 at 10-15 DAS, T₄: Black gram+ fodder cowpea as an intercrop (multi-cut) + 1 inter cultivation at 40 DAS, T₅: Black gram+ fodder cowpea as smothering crop in between rows of black gram, T₆: Black gram + fodder cowpea as an intercrop with in-situ incorporation on 35 DAS + 1 inter cultivation at 40 DAS, T₇: Mechanical (cycle weeder) weeding at 35 DAS, T₈: Two mechanical weeding at 20 and 40 DAS, T₉: Cucumber leaf extract 100ml l^-1 @ 2-4 leaf stage, T₁₀: Ageratum conyzoides leaf extract 100ml l^-1 @ 2-4 leaf stage, T₁₁: Hand weeding at 20 & 40 DAS and T₁₂: Un weeded check with three replications.

Results: The results indicated that significantly higher nutrient uptake by black gram was obtained in hand weeding at 20 & 40 DAS (T₁₁) (80.52 N, 15.89 P₂O₅ and 35.62 K₂O kg ha^-1) followed by stale seedbed technique + inter cultivation twice at 25 & 45 DAS (T₂) (79.04 N, 15.39 P₂O₅ and 33.98 K₂O kg ha^-1). The lesser uptake of the nutrient by black gram (39.29 N, 7.20 P₂O₅ and 14.43 K₂O kg ha^-1) and higher nutrient uptake by weeds (12.12 N, 5.87 P₂O₅ and 8.84 K₂O kg ha^-1) were noticed in un weeded check (T₁₂).

Conclusion: Organic weed management practices improved nutrient uptake and reduced nutrient loss to weeds in black gram. Hand weeding at 20 and 40 DAS, followed by the stale seedbed technique with inter-cultivation, is recommended for effective weed control and enhanced productivity under organic farming systems.