Eco-Friendly Weed Management Enhances Yield and Nutrient Uptake in Watermelon under an Organic Production System

Abstract

Weed control is challenging in organic vegetable farming because weeds compete with crops for water, nutrients, sunlight and growing space; however, chemical herbicides are generally not used in organic production. This study was conducted as a field experiment over two seasons, 2022–23 and 2023–24, at the AICRP on Weed Management Block, College Farm, Professor Jayashankar Telangana Agricultural University, Rajendranagar, Hyderabad, to evaluate eco-friendly weed-management techniques for enhancing fruit yield and nutrient uptake in watermelon. The experiment was conducted using a randomised block design with three replications. The nine treatments were groundnut-shell mulch, rice-husk mulch, polyethene mulch + intra-row hand weeding, rice-straw mulch + hand weeding, hoeing twice, fenugreek intercropping + hand weeding, tamarind-leaf aqueous extract + hand weeding, an unweeded control and chemical control using pendimethalin. Polyethene mulch + intra-row hand weeding at 30 days after sowing (DAS; T3) gave the maximum yield in both years (34.27 and 36.64 t ha⁻¹) and was statistically similar to rice-straw mulch at 5 t ha⁻¹ + intra-row hand weeding at 30 DAS (T4), which gave 33.97 and 34.64 t ha⁻¹. The unweeded control gave the minimum yields of 0.91 and 1.09 t ha⁻¹. Nutrient concentration and uptake varied significantly among treatments. The chemical control gave the highest N, P and K concentrations, whereas T3 gave the highest nutrient uptake among the non-chemical treatments, with N, P and K uptake of 27.93, 8.39 and 67.22 kg ha⁻¹ in 2022–23 and 27.91, 8.55 and 70.13 kg ha⁻¹ in 2023–24. The findings show that combining mulching with timely hand weeding reduces crop–weed interference while improving watermelon productivity and nutrient uptake. Rice-straw mulch with hand weeding and polyethene mulch with hand weeding were both effective mulch-based approaches.