How Safe is Chicken Litter for Land Application as an Organic Fertilizer? A Review

Area of Science:

• Environmental Science and Agronomy
• Public Health and Veterinary Medicine

Background:

• Chicken litter is a widely used, cost-effective organic fertilizer, particularly important for the expanding global poultry industry.
• Concerns exist regarding the safety of chicken litter for land application and its environmental release, with limited consolidated data.
• Potential risks include contamination by pathogens, antibiotics, antibiotic-resistant genes, hormones, heavy metals, and pesticides.

Purpose of the Study:

• To consolidate scattered information on chicken litter contaminants and their potential risks to human, animal, and environmental health.
• To evaluate if chicken litter, in its current form, meets minimum standards for safe land application as an organic fertilizer.

Main Methods:

• A comprehensive literature review and meta-analysis of technical reports, conference proceedings, peer-reviewed articles, and internet texts.
• Focus on identifying known contaminants and assessing their prevalence and potential impact based on existing data.

Main Results:

• Direct land application of chicken litter may pose risks to animal, human, and environmental health.
• Pathogenic bacteria, including *Escherichia coli* and Coliforms, frequently exceed permissible limits for land application.
• Contamination with *Actinobacillus*, *Salmonella*, antibiotic-resistant *E. coli*, antibiotics, and heavy metals is widespread in chicken litter globally.

Conclusions:

• Chicken litter, as currently applied, may not meet minimum safety standards for organic fertilizer use.
• There is a critical need for standardized safety regulations and rigorous studies, especially in developing countries, to ascertain contamination levels.
• Establishing and standardizing contaminant limits across agencies is essential for the safe disposal and land application of chicken litter.