By Neville Passmore
Australia has the potential to be the food bowl of Asia and at the same time feed our own population with high quality food. One of the long term worries however is the rundown of fertilisers resources, in particular phosphorus. This is one of the big three nutrients needed for plant growth, you may have heard this expressed as N.P.K or Nitrogen, Phosphorus and Potash.
These elements are present within the soil, on the surface, in water and in the atmosphere of our planet. The quantity is constant, in other words,these are never destroyed but they can become unavailable. Two examples - sequestering in landfill, or washing out into oceans where recovery is extremely difficult.
Phosphorus is a particularly concerning nutrient. The world’s supply of mineable phosphorus is dwindling with an estimated life of 40 to 100 years. Today 85% of the globes known high grade phosphorus ore resource is found in one country - Malta.
For me the inspiring thought is that much of the phosphorus in Australia is available for recycling, we just haven't cottoned on to how we can do it. Food waste is a brilliant example. These days we send it off to landfill with little thought. Not only do we need to develop ways to divert this material, as well as green garden wastes, into composting facilities that can turn rubbish into valuable composted products which enable us to capture this vital growing element and return it to our soils.
Western Australia's soils are extremely old and nutrient depleted. Over millions of years this part of the country has not had glaciers or volcanic activity to bring new nutrients to our soil. One of the great breakthroughs in agriculture was the discovery that the deficiencies in phosphorus could be overcome with applications of Superphosphate. Early results were spectacular so the annual regimes of application became almost religiously unquestionable.
Billions of dollars worth of Super have been deposited in wheat belt soils in WA and the worrying thing is most of it is still there, locked up in an insoluble form which is of no use to crops. Some of this material is finding its way through catchments and is flowing eventually out to sea. On the journey it is contributing to nutrient pollution and fuelling algal blooms in our waterways.
An astonishing attribute of some purpose - made very mature composted products is the ability to take up this sequestered phosphorus and turn it into a plant available form. This is a fascinating story I will keep you posted.
Another currently wasted phosphorus resource is human and animal solid wastes, yes I am talking about manure or poo. Whenever this material finishes up in landfill it adds to the loss of resources. If applied to soils in a raw form it can be very dangerous from a disease point of view, plus it tends to dump soluble nutrient such as nitrogen and phosphorus into our sandy soils to exacerbate the pollution of our waterways.
Modern day composting can take this smelly, toxic material and convert it into safe-to-use, sweet smelling composted product suitable for growing plants, including food crops. The high temperatures achieved in controlled composting pasteurise the mix killing off pathogens, weeds and even break down drugs and pharmaceuticals. We have to change some attitudes here.
Is there anything that we householders can do to make a difference to this global problem? Recycling food waste is a good start. This can be done through home composting. I have an Aerobin compost bin at home and this gets fed every day. Chooks are great value in recycling food waste as are compost worms in a worm farm.
Lobby for a third organics bin with your local council. The Bunbury- Harvey Regional council have just piloted a 'third bin' concept in their area and the public support has been outstanding with 55% of waste streams diverted from landfill in the first 6 months of operation and contamination results plummeting. This composting was achieved with a flexible aerated system called MAF. This is another story in its own right.
Use organic, ideally composted, soil improvers and mulch in your garden to build soils and reduce fertiliser needs. Composted material in the soil also holds on to nutrients and moisture, which is of great benefit to the soil but also reduces nutrient leaking.
So you can see that when I go on a bit of a rave about compost saving Western Australia from some of its greatest problems such as peak phosphorus, nutrient pollution, nutrient loss, low nutrient food, rubbish to landfill and depleted soils there is a real role here for composting. Not all composts are the same but that’s another story, stay tuned.
Home made compost