Impact of Vermiwash on the Growth and Yield of Green Gram (Vigna radiata) MI6

Green gram (Vigna radiata) cultivation in Sri Lanka heavily relies on inorganic fertilizers, leading to environmental and health issues that necessitate the exploration of alternatives; therefore, a field experiment was conducted at the Adaptive Research Centre in Vavuniya, Sri Lanka, to evaluate the impact of vermiwash on the growth and yield of the green gram variety MI6. Vermiwash was prepared using cow dung, banana fruit waste, mold leaves, and red worms (Eisenia fetida). Six treatments were established in a Randomized Complete Block Design (RCBD), including controls such as no fertilizer (T1) and 100% recommended inorganic fertilizer (T2). The remaining treatments combined half-doses of inorganic fertilizer with varying concentrations of vermiwash as a foliar spray: 25% (T3), 50% (T4), 75% (T5), and 100% (T6). The prepared vermiwash had a pH of 7.63 and contained total available nitrogen, phosphorus, and potassium at 0.014%, 0.355%, and 1.500%, respectively. The highest plant height, leaf area index, and number of branches were recorded in T5 (42.13±0.21 cm, 10.48±0.28, and 3.67±0.31, respectively), showing no significant difference (P > 0.05) from T2. The lowest days for 50% of flowering were observed in T5 (42±0). The highest number of pods per plant, pod length, pod girth, seeds per pod, 100 seeds weight, and total yield (27.17±0.78, 11.27±0.17, 2.29±0.02, 12±0.22, 7.18±0.10 g, and 212±1.49 g) were observed in T5, significantly different (P < 0.05) from T2. This study suggests reducing inorganic fertilizer by half and combining it with 75% vermiwash (T5) for optimal growth and yield.