Health Challenges caused by chemical fertilizer overuse by climate stressed communities in Kenya

DR. ANITA HANDA-CORRIGAN & ADV.RAHUL PADWAL (2/24/24)

Post War Shift from Cow Dung to Synthetic Fertilizers:

The history of using cow and buffalo dung as sources of fertilizer can be traced to ancient agricultural practices. The ancient Neolithic farmers used dung from their herds of cattle as a slow -release fertilizer as early as 6000BC. (1) In both Asian and African countries, cow dung has been used as a traditional soil fertilizer for decades (2). Since the production of K fertilizers in Germany in 1861 and synthetic calcium nitrate in 1903, the spectrum of synthetic 1933 post-war fertilizers has increased considerably. These include ammonium nitrate, urea ammonium phosphates, super phosphoric acids, and several others-grouped as NPK fertilizers. However, less than 50% of the nitrogen and phosphorus was taken up by the plants (3.4), the remaining lost by leaching into ground water and atmospheric volatilisation, causing serious environmental and economic problems (4,5,).

The acceleration of the global nitrogen cycle and increase of nitrogen oxide emissions of N2O (nitrous oxide) and NO (nitrogen oxide) from fertilized soil, contributes to global warming, ozone depletion, and groundwater contamination. The “hole in the pipe” model was conceptualized by Firestone and Davidson (6), it explains the flow of Nitrogen and N2O emission increased with synthetic fertilizer application rate. High temperature, low soil water, soil compaction, poor drainage and low oxygen levels all resulted in high N2O emission. Furthermore, N2O

emissions are high in soils that are not water saturated, at low pH, have sub-surface application of ammonium-based fertilizer, in soil that is compacted and in repeatedly tilled soils. (7) Five chemical forms of N fertilizers showed strong stimulation of N2O emissions, resulting in a staggering average emission increase of +493% (7).

The literature is abundant with articles that demonstrate the complexity of microbial interactions with biotic and abiotic factors that influence N2O emissions from the soil to the atmosphere. In combination with pesticides and toxic herbicides, the combined adverse effects on soil and human health are no longer sustainable, as summarized below:

• N₂O has a100 year global warming potential which is 298 times that of CO₂

• N₂O the most effective ozone-depleting gas

• Emissions from natural soils are 6-7 Tg N₂O-N yr^-1

• Fertilized soil emissions of N_@O increase dramatically at high temperatures (10)

• There is a 4.1% increase in the sales of inorganic fertilizers globally, and projected global sales of $309 billion by 2025- fuelled by growth of agriculture, feed, fuel and fibres industries (11)

• Fertilizers are the main cause of excess nutrient losses to the environment resulting in soil degradation, drinking water contamination by algal toxins due to eutrophication (11,12)

• There is a global problem of inadequate farmer training, poor nitrogen efficiencies and lack of good agricultural practices (12)

• Toxic trace elements such as mercury, cadmium, arsenic and lead can be found in fertilizers, and passed onto ruminants and humans in the food chain (13)

• Nitrogen fixation bacteria (eg Azotobacter, and Rhizobium) and denitrifying bacteria (Pseudomonas, Nitrosomonas, Nitrobacter and Azotobacter) had decreased diversity, abundance and sensitivity in inorganic, fertilized soil. (14)

• Climate change can significantly alter gene activation, N cycling, N mineralisation, nitrification and denitrification (14)

• N₂O emission can have both acute and chronic effects on human health; DIZZINESS

DISORIENTATION

IMPAIRED MEMORY AND COGNITION

ASPHYXIA

VOMITING

USED AS AN ANAESTHETIC, IT CAN CAUSE UNDESIRABLE

REPRODUCTIVE, NEUROLOGICAL AND IMMUNE TOXICITY

Cow Dung for Soil Fertilization

Cow dung is a valuable source of organic matter for soil enrichment; however, its use without proper treatment can lead to the spread of diseases among livestock and pose health risks to farmers. The key to mitigating these risks lies in adopting scientifically proven methods for manure treatment and decomposition.

Disease Risks in Untreated Cow Dung: Untreated cow dung can harbour various pathogens, including viruses, bacteria, and parasites, contributing to the transmission of diseases such as Foot and Mouth Disease (FMD), Bovine Spongiform Encephalopathy (BSE), and zoonotic infections. These risks necessitate the implementation of effective

manure treatment methods.

Key Advantages:

1. Nutrient-Rich Content: Cow dung is a potent fertilizer containing essential nutrients like nitrogen, phosphorus, and potassium, vital for plant growth.

2. Enhanced Soil Structure: The organic matter in cow dung improves soil structure, promoting water retention and aeration, which is crucial for plant development.

3. Microbial Activity: Cow dung supports beneficial microbial activity in the soil, fostering a healthy environment for plant roots.

4. Sustainable Waste Management: The use of cow dung as fertilizer aligns with sustainable farming practices, emphasizing the circular economy by recycling organic waste.

Contemporary Trends: Despite advancements in synthetic fertilizers, many farmers are reverting to or continuing the age-old practice of using cow dung due to its multiple benefits and environmentally friendly nature. In contemporary agriculture, where sustainability is a key focus, the trend of incorporating cow dung into conventional farming systems is gaining momentum. Its enduring popularity among farmers attests to the timeless wisdom of harnessing nature's resources for sustainable and eco-friendly agriculture, providing a bridge between the past and the future of farming.

Challenges and Innovations: While the use of cow dung as fertilizer is deeply ingrained in agricultural traditions, modern farming faces challenges related to scale, efficiency, and nutrient balance. Innovations such as composting techniques, bio-gas production, and controlled application methods are addressing these challenges, ensuring that cow dung remains a valuable and sustainable resource in the agricultural landscape.

Disease/ Health Risks of Untreated/ Fresh Cow Dung as a Fertilizer

Using untreated or fresh cow dung as a fer2lizer in soil can pose significant risks due to the presence of pathogens, viruses, and other infectious agents. Here's a detailed discussion on the diseases spreading risks associated with untreated cow dung:

1. Foot and Mouth Disease (FMD):

• Disease: FMD is a highly contagious viral disease affecting cloven-hoofed animals.

• Transmission: The virus can be present in saliva, milk, and manure of infected animals.

• Risk: Contaminated cow dung can contribute to the spread of FMD, affecting both animals and farmers during handling and application.

• Reference: World Organisation for Animal Health (OIE). (www.oie.int)

2. Bovine Spongiform Encephalopathy (BSE) - Mad Cow Disease:

• Disease: BSE is a transmissible spongiform encephalopathy affecting cattle.

• Transmission: Prions causing BSE can be present in nervous system tissues, including dung.

• Risk: Application of untreated cow dung may introduce BSE prions into the environment, posing a risk to animals and potentially humans.

• Reference: World Health Organization (WHO). (www.who.int)

3. Zoonotic Infections (e.g., E. coli, Salmonella, Cryptosporidium):

• Disease: Various bacterial and parasitic infections can be present in cow dung.

• Transmission: Faecal-oral transmission, especially through contaminated water or food.

• Risk: Direct exposure to untreated cow dung during handling or application can lead to infections in farmers and animals.

• Reference: Centre for Disease Control and Prevention (CDC).

(www.cdc.gov)

4. Parasitic Infections (e.g., Gastrointestinal Worms):

• Disease: Presence of parasitic eggs and larvae in cow dung.

• Transmission: Ingestion of contaminated food or water.

• Risk: Application of untreated cow dung may introduce parasitic agents into the soil, affecting animals and

potentially humans.

• Reference: Food and Agriculture Organization (FAO).

(www.fao.org)

5. Vector-Borne Diseases (e.g., Bovine Viral Diarrhoea – BVD)

• Disease: BVD and other diseases can be transmitted by vectors breeding in untreated cow dung.

• Transmission: Vectors like flies can spread pathogens from dung to animals.

• Risk: Presence of vectors can contribute to the spread of diseases among animals.

• Reference: Veterinary Parasitology.

(www.sciencedirect.com/journal/veterinary-parasitology)

6. Antibiotic Resistance:

• Risk: Untreated cow dung from animals treated with antibiotics can contain antibiotic-resistant bacteria,

contributing to the global issue of antibiotic resistance.

• Reference: World Health Organization (WHO). (www.who.int)

7. Methane Emission and Environmental Impact:

• Risk: Improper handling and disposal of untreated cow dung can contribute to environmental issues such as methane emissions, impacting climate change and air quality.

• Reference: Intergovernmental Panel on Climate Change (IPCC). (www.ipcc.ch)

8. Water Contamination:

• Risk: Runoff or improper disposal of untreated cow dung can contaminate water sources, affecting water quality and posing risks to aquatic ecosystems and human communities.

• Reference: Environmental Protection Agency (EPA).

(www.epa.gov)

Farmers need to adopt proper manure management practices, including composting and treatment, to minimize the risks associated with untreated cow dung. Following recommended guidelines for hygiene and protective measures during handling are crucial for preventing the spread of diseases to farmers and animals.

Mitigating the Risk of Untreated Cow Dung through Manure Treatment

Process

Untreated or fresh cow dung poses potential risks of disease transmission due to the presence of viruses, bacteria, and pathogens. This article explores the significance of proper manure treatment and the process of scientific decomposition in mitigating disease risks associated with untreated cow dung. Through a literature review, we highlight how high heat and scientific decomposition contribute to reducing the probability of disease transfer, emphasizing the importance of adopting these practices in agriculture.

1. Introduction: Cow dung is a valuable source of organic matter for soil enrichment; however, its use without proper treatment can lead to the spread of diseases among livestock and pose health risks to farmers. The key to mitigating these risks lies in adopting scientifically proven methods for manure treatment and decomposition.

2. Disease Risks in Untreated Cow Dung: Untreated cow dung can harbour various pathogens, including viruses, bacteria, and parasites, contributing to the transmission of diseases such as Foot and Mouth Disease (FMD), Bovine Spongiform Encephalopathy (BSE), and zoonotic infections. These risks necessitate the implementation of effective manure treatment methods.

3. Microbial Decomposition and High Heat: Scientific decomposition involves the controlled breakdown of organic matter through microbial activity. High heat generated during the decomposition process plays a crucial role in eliminating pathogens. As the temperature rises, harmful microorganisms, including viruses and bacteria, are effectively killed, reducing the risk of disease transmission.

4. Reduced Probability of Disease Transfer: Several studies have demonstrated that well-managed decomposition processes significantly reduce the probability of disease transfer through cow dung. Properly decomposed manure results in a more sanitized product, with decreased levels of pathogens. This reduced microbial load contributes to a safer environment for both livestock and farmers.

5. Significance of Manure Treatment for Disease Risk Mitigation: Scientifically decomposed cow dung holds several advantages in mitigating disease risks:

a. Pathogen Elimination: High-temperature decomposition ensures the elimination of a wide range of pathogens, including viruses and bacteria, minimizing the risk of disease transmission.

b. Improved Soil Health: Decomposed manure serves as a nutrient-rich organic fertilizer, enhancing soil structure and promoting healthy plant growth. This fosters a balanced ecosystem that supports livestock and reduces the likelihood of diseases. c. Environmental Protection: Proper manure treatment prevents the contamination of water sources, reducing the environmental impact of untreated dung runoff and safeguarding ecosystems.

6. Conclusion: In conclusion, the mitigation of disease risks associated with untreated cow dung is achievable through the adoption of proper manure treatment and scientific decomposition. The high heat generated during decomposition plays a crucial role in eliminating pathogens, reducing the probability of disease transfer. The significance of these practices extends beyond disease prevention, contributing to improved soil health, sustainable agriculture, and environmental protection.

In a randomised trial Hendarto et al (2018) showed that the application of a mixed cow dung of 24 tons per hectare and urea preparation at 25 Kg per hectare gave the best growth and production of Bracharia hybrid cv Mulato grass (17) The oxides of nitrogen dissolve in water to form nitrous acid, HNO2., which reacts with urea to form nitrogen, carbon dioxide and water. The salient problem in publications like these is that there is no consideration of the climate change and dose-dependent toxic effects of inorganic, organic and mixtures of fertilizers. It is clear that the health implications of exposing climate-vulnerable communities to agricultural chemicals and raw cow dung need to be urgently assessed.

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