INFLUENCE OF NPK NANO FERTILIZER ON MICROBIAL COMMUNITIES AND CHEMICAL PROPERTIES IN PADDY RICE (ORYZA SATIVA L.)

Abstract

Rice (Oryza sativa L.) production in sub-Saharan Africa faces challenges from declining soil fertility to inefficient nutrient management. This screen house study assessed the effects of banana peel-synthesized NPK Nano fertilizer at four rates (Control, 50%, 75%, and 100%) on soil microbial communities, enzyme activities, arbuscular mycorrhizal fungi (AMF) diversity and root colonization, nutrient availability, and root morphology in two lowland rice varieties (NERICA L-19 and WITA-4) using a 4 x 2 factorial in a Completely Randomized Design with three replicates. NPK Nano fertilizer significantly increased bacterial populations up to 9.9 x 10⁵ CFU g⁻¹, fungal populations up to 19.0 x 10³ CFU g⁻¹, and soil enzyme activities, including amylase (315.0–601.4 mg kg⁻¹), urease (21.80–24.90 mg kg⁻¹), and alkaline phosphatase (122.03–138.6 mg kg⁻¹). AMF root colonization, including arbuscules, hyphae, and vesicles, increased significantly in a dose-dependent manner, with 100% Nano priming reaching 74.33%, 49.50%, and 30.00%, respectively. Five AMF genera were identified: Acaulospora, Funneliformis, Gigaspora, Glomus, and Rhizophagus, with spore density inversely related to Nano fertilizer rate. Soil nutrient availability showed no significant treatment effects, likely reflecting efficient plant-mycorrhizal nutrient uptake. Root fresh weight was significantly highest under 100% Nano priming (42.5 g), while NERICA L-19 exhibited greater root elongation. PCA and correlation analyses confirmed strong positive relationships among Nano fertilizer rate, enzyme activities and AMF colonization. These findings establish NPK Nano fertilizer as a promising tool for enhancing the rhizosphere and promoting sustainable lowland rice production in West Africa.