Storage duration and temperature affect pathogen load, heavy metals, and nutrient levels in faecal derived fertiliser

Area of Science:

• Agricultural Science
• Environmental Science
• Microbiology

Background:

• Faecal-derived fertiliser (FDF) safety is debated due to potential pathogen persistence and nutrient changes during storage.
• Little research exists on abiotic factors like temperature and duration affecting FDF storage.
• Concerns include indigenous pathogen regrowth and nutrient alterations in stored FDF.

Purpose of the Study:

• To assess the impact of storage temperature and duration on indigenous E. coli regrowth and NPK content in two types of FDF.
• To evaluate nutrient stability and microbial safety of enriched co-compost (NECo) and co-compost (Co) under various storage conditions.

Main Methods:

• A 2x3x6 factorial design with 36 experimental conditions and three replications was employed.
• FDF samples were stored for 6 months under varying temperatures (5°C, 25°C, 35°C) and durations (monthly).
• Analyses included pH, EC, organic carbon, N, NH4-N, NO3-N, P, K, E. coli, and total coliform.

Main Results:

• Storage temperature and duration did not significantly affect indigenous E. coli regrowth or total nitrogen in NECo and Co.
• Ammonium-nitrogen (NH4-N) concentrations in NECo decreased by 27-55% with increased storage duration at 5°C and 25°C.
• No significant impact on other NPK nutrients or E. coli regrowth was observed across tested conditions.

Conclusions:

• FDF, including NECo and Co, is safe for storage as indigenous E. coli regrowth and total nitrogen levels remain stable.
• Extended storage does not necessarily lead to significant nutrient losses in FDF.
• Further research on the effect of moisture content during FDF storage is recommended.