DIVERGENCE BETWEEN NUTRIENT ENRICHMENT AND AGRONOMIC RESPONSE OF MELON UNDER PUMAKKAL-ACTIVATED COTAYAM COMPOST

Abstract

The development of microbially activated organic fertilizer is an important strategy for improving horticultural productivity while utilizing locally available organic waste. This study aimed to analyze the divergence between compost nutrient enrichment and the agronomic response of melon (Cucumis melo L.) to Cotayam compost fermented with different Pumakkal isolate formulations. Cotayam compost was prepared from cocopeat, shrimp-pond sediment, and chicken manure, and fermented under six treatments: P0 without isolates; P1 with three isolates; P2 with six isolates; P3 with nine isolates; P4 with twelve isolates; and P5 with fifteen Pumakkal isolates. The experiment employed a completely randomized design with six replications. The observed parameters included moisture content, total N, P₂O₅, K₂O, plant height, stem diameter, branch number, flowering time, fruit weight, and fruit sweetness. The results showed that increasing the number of Pumakkal isolates enriched compost nutrient content, with the highest values recorded in P5: 2.462% total N, 1.870% P₂O₅, and 2.237% K₂O. However, the most favorable agronomic response was observed in P3 rather than P5. P3 produced the highest plant height of 167.10 cm, the largest stem diameter of 12.83 mm, the earliest flowering at 13.67 days, the highest fruit weight of 1093.17 g, and high fruit sweetness of 15.40 °Brix. These findings indicate that the effectiveness of Pumakkal-activated Cotayam compost is not determined solely by the highest nutrient concentration but is likely related to how compost-derived nutrients meet crop physiological demands during growth and fruit development. Therefore, the nine-isolate formulation represents the most promising treatment for supporting melon production using locally sourced Cotayam compost.