GARDENERS ARE EARTH SAVIOURS
CAN SIMPLE HUMUS BE THE ANSWER?
LAST week, I was fortunate to be able to attend a 4-day course in sustainable agriculture, conducted by a Queensland-based manufacturer and supplier of a range of mostly natural and organic products for farmers, production horticulturists and home gardeners.
The CEO and co-founder of this innovative company was the key speaker for the four days, and I must say, I’ve come away from this course with a renewed determination to teach and inform my TAFE students, and readers of this gardening page, about the benefits of improving our soils, using organic and natural products to supply plant nutrients, and in particular, increasing the amount of a wonderful substance in our soils called humus.
Firstly, let’s look at the big picture. There is no doubt that industrialisation, deforestation, burning of fossil fuels, outdated agricultural practices and, believe it or not, cement production, have contributed to the massive build-up of carbon dioxide (CO2) in our atmosphere over the last 250 years.
Needless to say, this has accelerated global warming to the point where it’s believed that there may be a worldwide 3.5 degree celsius increase in temperature by 2035.
Many scientists agree that this could easily be the point at which life on this earth begins to die out.
This includes we humans.
Now whilst governments bicker and procrastinate over whether global warming is real, what their emission targets will be, or who’s to blame, our atmosphere is rapidly filling with CO2, weather events are becoming fewer and more violent, wildfires are destroying forests and communities, our oceans are turning acid and dying, and we’re losing precious topsoil due to water and wind erosion (two dust storms in the last two weeks!).
Now it’s widely acknowledged that increasing the amount of organic matter in the earth’s top 30cm of soil can create a massive “carbon sink” effect which, if embraced world-wide, could easily reverse the current accelerating increase in CO2 saturating our atmosphere and oceans.
Obviously, those who farm our soil on a large scale need to stop the loss of organic matter from their properties by practising sustainable farming methods, such as zero or minimum-till, inter-row plantings, and cover cropping.
As gardeners, we can each also play a small but significant role in helping to slow the increase in global CO2 levels.
How?
A word of warning – for some of you, it will mean thinking quite differently about the way you garden.
For others, it will be “business as usual”. Firstly, you will need to reduce and eventually cease using any forms of chemical (synthesised or inorganic) fertilisers, fungicides, herbicides and pesticides in your garden.
Many of these chemicals use large quantities of resources and energy in their manufacture, and they will damage the environment each time they’re used in your patch.
It’s a known fact that chemical fertilisers affect soil microbe levels (the very organisms that help to reduce atmospheric carbon), and pesticides, herbicides and fungicides will no doubt kill non-target organisms when used (even according to the label!).
For example, fungicides containing copper will kill earthworms as well as beneficial bacteria and fungi.
In future articles, I’ll help gardeners to choose from organic and natural forms of these products.
Secondly, resist the temptation to cover your soil with pavers, concrete and bitumen. Leaving soil open to the elements means that precious rainwater will infiltrate and percolate through the soil profile, helping to maintain underground water sources.
In addition, utilise your garden soil areas by planting with ornamental, or preferably, productive plants.
Every extra plant we grow will remove carbon dioxide from the atmosphere and release oxygen, essential for most varieties of organic life, including us.
Thirdly, and most importantly, improve your soil by increasing its ability to hold water, air and nutrients.
How?
Quite simply, add organic matter in the form of animal manures, green manures, and composts.
Some quick maths will reveal that if you can increase the organic matter in a square metre of soil by 1%, it will remove 8.8kg of CO2 from the atmosphere.
Not only will it reduce CO2, this 1% increase in organic matter will hold an extra 17 litres of water per square metre of soil too.
Imagine the combined effect of this increase over 100 square metres in a million home gardens (actually equal to 880,000 tonnes of CO2, and 1.7 billion litres of water)?
It’s best to use a quality compost for your organic matter, as fresh animal and green manures tend to use vital nitrogen from the soil when being broken down by soil organisms.
Now we get to humus.
Humus is the active and inactive remains of organic matter that has been broken down by soil organisms. It can hold massive amounts of water and available nutrients for your plants. What does this mean to the Suburban Backyard Producer?
It means a massive increase in the nutritional value of your home-grown food.
High humus levels reduce the need for chemical intervention in the garden, as it increases the resilience of plants to disease and pest attack.
Humus binds soil particles to help improve soil structure.
Humus will also act as a carbon filter and will aid the removal of heavy metals and chemical residues.
Gardeners can produce their own organic matter by composting as much garden waste as possible.
We CAN contribute to the reduction of our atmosphere’s carbon dioxide levels.
Get composting now!