V3I5P64

Optimization of Nutrient Stabilization and Agronomic Efficacy in Oryza sativa via Lactic Acid Fermentation of Source-Separated Human Urine : A Sustainable Circular Economy Framework in Madagascar  

RATOLOTRANOMENJANAHARY Xavier Etienne Urbain¹, ROBIJAONA RAHELIVOLOLONIAINA Baholy ^1,2,3

Abstract

This study investigates the transformative potential of Lactic Acid Fermentation (LAF) as a sustainable strategy for converting human urine into a high-performance bio-fertilizer for rice (Oryza sativa) cultivation. While raw urine is rich in essential macronutrients, its direct agricultural application is often hindered by ammonia volatilization, phytotoxicity risks, and social acceptability challenges. Through a methodology involving a 60-day storage period followed by a 36-day fermentation phase using an indigenous lactic inoculum, this research evaluates the biochemical stabilization and agronomic efficacy of the resulting substrate compared to a traditional benchmark (BIOLIFER associated with zebu manure). Physicochemical results demonstrate that the LAF process effectively stabilizes the substrate, maintaining a high ammonium (N-NH₄⁺) concentration of 3,346 mg/L and reducing organic matter by 84% (from 0.564% to 0.088%). The stabilization of pH at 9.28 serves to inhibit the enzymatic degradation of urea, thereby preserving the fertilizing potential. Agronomically, LAF-treated seedlings exhibited a 23.9% increase in vertical development, achieving a terminal mean height of 32.02 cm (F = 70.25, p < 0.05). This early-stage vigor translated into a significant yield increase at harvest, with the LAF modality reaching 2.2 t/ha, representing a 22.2% improvement over the 1.8 t/ha recorded for the control group. These findings suggest that LAF not only preserves critical NPK components but also fosters beneficial soil-plant interactions through microbial synergy. Consequently, LAF emerges as a viable, locally-sourced alternative to commercial fertilizers, supporting circular economy principles and enhancing crop productivity in resource-limited tropical environments.

Keywords:

Lactic Acid Fermentation, human urine, Oryza sativa, circular economy, bio-fertilizer, nutrient stabilization