How becoming an organic gardener solves most gardening problems

Clive Blazey questions Tim Marshall, an organic gardening expert who links organic gardening to climate change solutions

CB:  Why do gardeners need to be organic?

TM:  For home gardeners an organic approach is the best thing they can do for their gardens.  Organic methods are at least adequate and almost always the best option for maximising production, favouring biodiversity and building plant and soil health, and there are no contrary indicators whatsoever.

In our home gardens we can afford the simple inputs that build soil depth and fertility.  Products such as compost, seaweed, fish hydrolysate, mineral fertilisers, trace elements in safe sulphate or oxide formats and natural mulch materials can easily sustain food and ornamental gardens without recourse to synthetic products with their carbon-destroying negative impacts.

For pest and disease control, almost all problems can be resolved with traditional and new products.  Simply caring for soil fertility and biological health, selecting suitable plants and varieties, paying attention to basic cultural practices (such as timely and adequate watering) and physical controls (such as traps, barriers, hand picking) will keep many potential problems at bay.  There are now plenty of horticultural soaps and oils, biological pesticides (e.g. Dipel), plant extracts (e.g. Azadirachtin) and useful products such as non-drying glues and floating row covers.

Our yards are where the kids and pets hang out, we produce at least some of our food, and expect to be entertained by nature, such as our wonderful native parrots and finches.  Why would we use dangerous chemicals here, especially if we aren’t trained for that purpose?

Weeds can be harder work if you have the wrong ones.  The answer is good design, blocking them out, as well as some time doing peaceful hand weeding. It can be relaxing with the right tool and attitude!

CB:  Does RoundUp kill mycelium?

TM:  Fungal mycelia are found in the top 60 centimetres of the soil.  Where there is plant or mulch cover, most of them will be close to the soil surface.  They are killed by cultivation, strong synthetic fertilisers and herbicides.  RoundUp and many other herbicides kill fungi by direct action, but they also remove the non-crop plants that sustain mycelia between crops or when garden plants are dormant.  Without something to grow alongside in a symbiotic relationship, they will simply fade away (avoid long fallow in your organic garden).

CB:  Why is mycelium so important in soil biology?

TM:  We used to think that only some plants developed symbiosis with fungi, and that they were mainly important for savaging some phosphorus or zinc. Now we know that more than 80% of species develop these special relationships and that mycelia can provide
a wide range of nutrients and water to plants, and that most plants prefer to get their nutrients this way.

Mycelia grow into or around plant roots and exchange some carbohydrates from photosynthesis for the nutrients they acquire from the soil.  They are so exploitative of the soil that they effectively increase plant roots by 10 to 60 times.  Fungi have enzymes that allow them to break down woody wastes that are difficult for bacteria to access.


CB:  Can soil microbes slow climate change, i.e. can they increase carbon storage?  Is mycelium the largest living organism on the planet?

TM:   Soil biology contains carbon, facilitates the breakdown of plant residues into humus, which is a very long-term carbon storage system, and soil biology supports plant life which removes and stores carbon.

In the 150 or so years of ‘modern’ agriculture, during which we de-emphasised soil microbes, we relied upon synthetic nitrogen such as urea, sulphate of ammonia and anhydrous ammonia to break down plant residues and mineralise the nutrients they contain (mineralise is the term we use for converting unavailable organic nutrients to a plant-available form).

Manufacture of synthetic nitrogen is itself an energy intensive and polluting process, much of the synthetic nitrogen is leached or volatised, making it an essentially wasteful system, and in the process of mineralising nutrients, carbon is largely burnt up. Systems that rely on synthetic nitrogen, therefore, are usually not improving soil carbon, and all but the very best managed are losing soil carbon.

While microbes are performing these mineralising and carbon sequestration functions, they are simultaneously providing other useful services, including manufacturing pest and disease defence chemicals that are important
to plant and human health.

Yes, the largest, single, living organism on the planet is a huge network of interconnected mycelia belonging to the honey fungus (Armillaria ostoyae) living in a forest in the Malhuer National Park in Oregon, USA.  It may not weigh as much as the highest biomass organism, the Pando forest in Colorado (a clonal colony of quaking aspen, aka Populus tremuloides), but it covers a much greater area – something like 8.9 square kilometres.

CB: Should we be worried about the global decline of insects?

TM: Bee decline came to our attention some years ago but now evidence is building that many insect species are in serious global decline. The cause is still being investigated but it is obvious that habitat destruction and pesticides both play an important role.
We clearly should be concerned about bees because of their vital pollination function and importance in food supply, but we should also take note of the bigger picture.
Insects support pollination of indigenous plants around the world as well as crops, and they are the food supply for many birds, reptiles, small mammals and other organisms. As they decline so, inevitably, ecosystems are damaged. We knew back in the 1960s that pesticides were being distributed around the world in food chains and by wind, causing raptor eggs to fail.
We even find them in penguin eggs in the Antarctic. Insect decline is more evidence of the pernicious and long-term effects of chemicals and should cause us to rethink any instance of prophylactic and unnecessary chemical application.

CB:  What is the connection between wheat intolerance and modern agricultural methods?
TM: Developed economies that rely largely upon a Mediterranean diet are all reporting an increase in chronic inflammatory conditions such as coeliac disease. Coeliac conditions result from allergy (or in lesser cases, sensitivity) to the protein gluten. Gluten forms the bonds that allow bread to rise and stay together without breaking apart.

Many types of cereal contain gluten, but modern bread wheats have been bred to greatly increase gluten content, so the first impact of industrial agriculture is simply the intensive breeding that has increased gluten content.
For people with minor sensitivity, simply choosing sourdough bread from non-wheat grains such as rye may be effective at reducing inflammation. People with a serious allergy need to avoid it altogether.
More controversially, some researchers have found that glyphosate residues in food (especially but not limited to grains) are killing gut bacteria, damaging intestinal villi and making gluten less digestible.
Some researchers dispute this claim or call for more evidence. What is indisputable is that we swallowed the ‘RoundUp is safe’ message so well that we developed a significant ‘chemical dependency’ on glyphosate and
we are now burdened with soil, water and food residues from glyphosate use.
Additionally, cereal production is the most energy intensive farming system and therefore causes significant carbon emissions and contributes to global warming.
A truly carbon-friendly diet need not be meat or wheat-free but would see us consume more volume and diversity of vegetables.


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