Effect of Organic Amendments and Black Polyethylene Mulch on Growth, Flowering, Yield and Economics of Watermelon (Citrullus lanatus) in Assam Condition

Watermelon production in Assam may be influenced by nutrient management and surface mulching A field experiment was conducted during 2021–22 and 2022–23 at Nabanita Organic Farm, Potia Fokola Gaon, Jorhat, Assam, to evaluate organic nutrient sources and black polyethylene mulch for watermelon (Citrullus lanatus) cv. Saraswati. The experiment comprised two main-plot treatments (without mulch and black polyethylene mulch) and seven subplot nutrient treatments in a split-plot design with three replications. Nutrient treatments included an untreated control; the recommended dose of fertilisers (60:40:60 kg ha⁻¹ NPK) with farmyard manure (FYM); FYM with a microbial consortium; vermicompost with a microbial consortium; enriched compost; FYM plus vermicompost with a microbial consortium; and FYM plus enriched compost. The combined treatment of FYM (2.5 t ha⁻¹) + vermicompost (2.5 t ha⁻¹) + microbial consortium (5 kg ha⁻¹) under black polyethylene mulch (M1T6; S13) produced the strongest overall crop response. It recorded vine lengths of 65.01, 182.68 and 328.80 cm at 30, 45 and 70 days after sowing (DAS), respectively, and a fruit yield of 41.86 t ha⁻¹ in the pooled analysis. The same treatment recorded a fruit yield of 20.93 kg vine⁻¹ and 62.79 kg plot⁻¹. The net return and benefit–cost ratio were Rs. 6,82,042 ha⁻¹ and 4.40, respectively. The results indicate that the application of FYM, vermicompost and a microbial consortium combined with black polyethylene mulch was the most productive and economically favourable treatment under the Jorhat conditions during the study period.