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  • Nutritional Value of Compost

    Nutrients in Composting

    Posted by Angus Stewart

    Aug 20

    Nutritional Value of Composts

    Compost is an inherently variable material when it comes to nutrient content.  It very much depends on what materials go into building the compost heap and also the stage of maturity or decomposition the compost has reached at any particular moment in time.  By maturity I mean, the composting process takes organic materials of all sorts, and breaks them down into smaller chemical components, which can then be utilised by plants. This process can take variable amounts of time. If there’s a lot of nutrition available in the compost heap then the process will happen very quickly as there is plenty of fuel available for the microbes to break down the organic matter to work with, if there are large amounts of woody materials (carbon) with a lower nutritional content, there is a limited range of organisms which are able to break down that organic material.  In general terms this takes a lot longer than green or nitrogen rich materials.

    There are some other necessary ingredients for effective nutritious composting.  There are numerous organisms that can break down organic matter, and they can live under quite variable conditions.  Anaerobic composting will create a different nutrient mixture in the final product as compared to aerobic or worm assisted composting.

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  • Burying your Kitchen Scraps/Trench Composting

    How to bury your Organic Waste

    Posted by Angus Stewart

    Aug 20

    Burying your kitchen scraps, or ‘Trench Composting


    This is arguably the simplest and most effective method of composting high nutrient material such as kitchen scraps. The basic concept is to simply dig a hole, around 30cm - 40cm deep, this is most effective if done into the topsoil layer to suitable depth, as this is the soil layer where most earthworms feed, live and reproduce.  What happens during this process is that the natural earthworm population present in most soils will expand to utilise the extra food source that has been created in the soil. As well as earthworms there will also be fungi and bacteria present in the soil as well that live on organic matter, so it is the same process that happens in a compost heap in that these organisms will breed up to utilise the organic material.

    The benefits to the soil are enormous, there are direct advantages from the earthworms digesting the organic matter and releasing the nutrients from that in an available form to plants for growth. The earthworms will also be moving in and out of the surrounding soil and tunnelling as they do this they aerate the soil, creating little channels through which water, air and plant roots can move freely, greatly aiding plant growth.


    Many of the micro-organisms which are found in the digestive tract of earthworms are actually beneficial to plant growth and are excreted dispersed throughout the soil along with the nutrients and humus that the worms create. These beneficial micro-organisms act in several ways to benefit plants; they can antagonise pathogenic organisms by competing with them and reducing their populations in soil. Some organisms naturally produce antibiotic substances which can kill pathogenic organisms such as bacterial soft rots.


    In conclusion, the process of burying kitchen scraps to form an in-ground compost heap in topsoil is a very efficient way of composting.  
    The best way to practice this method of composting is to keep practice a rotation system operating in the home vegetable garden.  This means keeping one bed free of plantings each season to use as a composting site and allow the soil to be replenished. The time required for this composting process (in particular for high nutrient materials like banana peels and potato skins) is between one and two months. This allows sufficient time for this matter to be broken down into the soil by the earthworms, fungi and microbes. The earthworm castings are key to creating an ideal soil environment for plant growth by renewing the nutrients in the soil and rebuilding the structure of the soil.


    There are sometimes issues with seeds and things like potato peels actually sprouting new plants in your compost. These ‘volunteer plants’ are fairly easy to deal with, there are a couple of options there, the first is to simply dig these back into the compost where they will break down, plants like tomato and pumpkin seedlings, watermelon, rockmelon, potatoes and sprouts can all be dug back into the compost at least a week before planting. This will act as a green manure in the soil adding nutrients and humus as it breaks down further.  The other option is to let those plants grow if they have coincided sprouted during the appropriate growing season, things like cherry tomatoes can form productive healthy plants from these volunteers if replanted. Burying your kitchen scraps is a very effective method of composting, provided you have sufficient space to implement a seasonal rotation system in your garden.

    Note:

    Avoid composting or replanting plant material that is obviously diseased or carrying mould or fungal infections as some organisms can survive the composting process and spread disease.


    There are a few leaf borne viruses and infections that are the exception to this rule and can be safely buried in this type of composting system. These include foliar problems like black rot and fruit with brown rot, and most powdery mildews and rusts as these cannot survive for long once the leaves have fully biodegraded in a healthy compost heap.

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  • Safety Aspects of Composting

    Keeping safe when dealing with Compost

    Posted by Angus Stewart

    Aug 20

    Safety Aspects of Composting

    Compost is a complex biological material that contains all sorts of different organisms, bacteria and fungi in particular, but also potentially other organisms such as viruses and yeasts. Many of these are harmless or beneficial soil organisms; however there are some commonly found organisms which can cause health problems in humans.

    There are definite health risks associated with many of these organisms that can be pathogenic to animals, including infections, respiratory problems and gastrointestinal problems. Legionnaire’s disease for instance is caused by bacteria of the Legionella species which can be present in both compost and also potting mixes. These species are found quite widely in Australia; and potting mix and compost is usually sold with a safety notice regarding this risk. There is a risk of inhalation of aerosol particles of Legionella and other bacteria from commercial potting mixes and composts, and also from soil and compost in garden beds and containers. It is very important that anyone working with compost is aware of these risks and if they feel they are at risk, to take appropriate precautions, including wearing a dust mask when handling soil or compost, and washing hands thoroughly afterwards.

    There are many organisms found in soil which can cause problems.  

    The most common paths of infection are through inhalation of bioaerosols, or ingestion of bacteria or spores, however, there are also pathogens which can enter directly through the bloodstream through cuts and wounds. Another of the more commonly found organisms in organic materials is the bacteria that causes tetanus, which can enter the bloodstream through cuts and lesions. Prevent soil or compost from coming into contact with any open cuts or wounds, in the case of tetanus immunisation is recommended and is widely used as a preventative measure.

    Another area of concern is pathogens that can cause gastrointestinal problems such as Escherichia coli (E.coli as many people would know it). There are numerous strains of this bacterium, many of which are harmless and are a normal component of the gut of many mammals. However, there are other strains that can cause food poisoning and so the use of manure from mammals such as dogs and cats as well as meat scraps can be a risk factor and as such it is probably best to exclude these from your home compost unless you have a good working knowledge of how to minimise the risks of infection. Dog and cat manure can also contain pathogens such as roundworms and Giardia that can cause gastrointestinal problems. Avoid contact with the skin by wearing long sleeves and gloves and wear a face mask as well if you want to compost such materials.

    Another health concern when working with compost which must be considered is the fine particles of soil or compost which are created when working with dry materials.

    It is important to take precautions against inhaling fine particles of dust, particularly for those with Asthma and other respiratory ailments.  Wearing a dust mask will greatly assist in mitigating the risk of inhaling these particles, particularly when you are turning your compost or applying to soil or as mulch, as this is when stirring it up can create clouds of fine dust which poses a risk when inhaled. Fungal spores, dust mites and other organisms can be potential health issues especially for those with respiratory problems or compromised immune systems.

    Common precautions should always be taken against inhalation or ingestion of soil and compost particles, particularly if you are in high risk groups including those over the age of 50 and people with immune or respiratory problems including asthma.

    It is always good practice to wear a dust mask, gloves, wash hands frequently and ensure your tetanus vaccinations are up to date. Dry material should be dampened slightly by hosing or watering gently before disturbing it, this applies to compost, soil and potting mix, including when repotting container plants. Working in a well ventilated area will further reduce the chance of particle inhalation.

    Composting is generally a very safe activity if you adopt an informed and common sense approach, however, it is vitally important to recognise that there are health risks and that by taking appropriate precautions you will be a happy and above all, healthy composter!

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