Handling organic materials

Gardening improves the health and wellbeing, both physically and mentally, of millions of people around the world. But some gardening practices can in rare cases makes people ill. This blog post aims to make you aware of how to best handle soil, mulch, compost, manure, hay and other organic materials. If you follow a few rules, then handling these materials will be very safe!

I began to look into this topic after discussion with Food Garden Group member Margaret W, who is an entomologist (expert on insects). She pointed me towards some interesting reading on the subject. Thank you, Margaret!

I am going to focus on what to be aware of, and how to handle materials safely, so you can virtually rule out any chance of health issues, rather than focusing on the many diseases that in rare cases are transferred to humans via organic materials.

Recognising potentially harmful situations

Adding new soil, mulch, compost, manure, hay and other organic materials to your garden increases the microbial diversity in your soil.  Most of the microbes (bacteria, fungi and viruses) are beneficial ones for both soil and humans. However, in rare cases there can also be microbes in these organic materials that are harmful to humans. 

In the vast majority of situations where some unhealthy microbes are present, they will not get a chance to multiply. They will never become a problem. However, there are rare situations in which microbes that are harmful to humans do multiply and thrive: 

1. situations where organic material is exposed to temperatures that are above normal for extended periods of time
2. situations where organic materials are exposed to water for an extended period of time
3. situations where organic materials are held in dry conditions for extended periods of time

These conditions can be present in bags of manure, bags of mulch, bags of soil, bags of potting mix, bags of compost, mouldy hay bales, neglected heaps of lawn clippings, weed teas, compost teas, and neglected compost heaps. Hay which is darker in colour than usual or has a musty smell is indicative of mould being present.

In order to kill aggressive weeds, some people put weeds in a bucket of water for an extended period of time, rather than putting them on the compost heap where they might survive. The weeds will decompose in what is an anaerobic process, a process without air.  That process can in some cases produce harmful microbes.

How can microbes enter our body?

Here are the most common ways that unhealthy microbes could potentially enter the human body:

1. We breath them in
2. They enter through our skin - possibly through a little cut on our hand
3. We may swallow them

How do we make these situations safe?

Now that we are aware of the risks, we can take some easy steps to make the process of handling organic materials a lot safer. 

Depending on the situation you may want to adopt some or all of the suggestions below:

1. Always open bags with organic materials where there is good ventilation
2. Direct bags away from you when opening them
3. Wear a dust mask when opening and emptying bags of organic materials
4. Wear gloves when handling organic materials
5. Make dry organic materials moist before handling them to limit the number of airborne particles
6. Wear a dust mask and wear gloves when shredding with your mower or shredder dry grass clippings, hay, manure and weeds, or when pulverising manure 
7. Wear a dust mask when handling hay or heaps of manure
8. Make sure that organic materials that are kept moist or wet for an extended period of time also have access to air
9. To avoid anaerobic processes add air to the composting process in your compost heap by remixing the heap once in a while
10. Avoid using manures directly on your garden. By putting them through a composting process first, the possibility that harmful bacteria enter your garden is minimised. 
11. Wash your hands afterwards.  
12. Consider putting the clothes you wore in the washing machine.

Margaret referred me to an article on the web site of the National Centre for Farmer Health. Here is a quote from this article:

As a minimum precaution when handling mouldy hay or composting vegetation, reduce your exposure to spores and dust by wearing a P2 mask that complies with Australian Standards. Fitting the mask correctly is essential, as the presence of facial hair such as beards or even being unshaven can reduce the effectiveness of the mask. 

For the complete article see https://farmerhealth.org.au/2014/03/20/aspergillosis 

an example of a P2 mask

P2 masks (example in the photo above) are available at most hardware stores.

Be aware and all will be fine!

Ill health as a result of exposure to bad microbes while gardening is rare, but read about some the cases that have happened, and you begin to realise that it is best not to ignore the risks.

Wishing you happy and healthy gardening,

Max Bee