Enhancing NPK Fertilizer Efficacy and Ultisol Chemical Characteristics by Arbuscular Mycorrhiza in Watermelon Cultivation

Ultisols, characterised by elevated acidity and decreased nutrient availability, restrict watermelon production (Citrullus lanatus). This study assesses the impacts of arbuscular mycorrhiza (AM) and different NPK fertiliser concentrations on watermelon production at Ultisol. Employing a random block design, the results demonstrated that AM inoculation raised the soil pH to 6.05. The 75% NPK dosage (P3) augmented phosphorus availability (50.56 ppm) and enhanced fruit weight (3.25 kg), circumference (54.19 cm), and length (37.81 cm). Significantly, the combination of AM and 75% NPK (M1P3) optimised soil organic carbon (6.45%) and fruit sweetness (13.90 Brix), surpassing the 100% NPK treatment. In summary, the application of the Glomus and Acaulospora consortium, with 75% NPK, is ideal for improving ultisol characteristics, increasing watermelon output, and diminishing fertiliser needs.