Nutrition basics: Soil Quality and Fertiliser

Let's talk about soil!

A plant is only as nutritious as the soil it was grown in. It makes no difference how many serves of fruits and vegetables you eat per day, if they are grown in nutrient-poor soil they won't be as good for you as you think.

Australia has some of the oldest land surface on earth and while rich in biodiversity its soil is among the most nutrient poor and unproductive in the world. This is due mainly to the country's geological stability, which is a major feature of the Australian land mass, and is characterised by, among other things, a lack of significant seismic activity. Only six per cent of the Australian landmass is arable. Large volumes of water are required from both surface and groundwater supplies. Australian soils are highly dependent upon vegetation cover to generate nutrients and for stability. Land clearing, water extraction and poor soil conservation are all causes of a decline in the quality of Australia's soils. (Source: Australian Government).

For this reason, the agriculture industry uses fertiliser on its crops.

Organic versus chemical fertilisers

Organic fertiliser is usually made from plant or animal waste or powdered minerals. Examples include manure and compost, as well as bone and cottonseed meal. They are sometimes sold as 'soil conditioners' rather than as fertiliser, because the nutrient ratios are difficult to guarantee. Organic fertilisers may be processed in a factory or at a farm. Organic fertilisers improve the structure of the soil and increase its ability to hold water and nutrients. Over time, organic fertilisers will make your soil and plants healthy and strong. Since they are the ultimate slow-release fertilisers, it’s very difficult to over fertilise and harm your plants. There’s little to no risk of toxic build-ups of chemicals and salts that can be deadly to plants. Organic fertilisers are renewable, biodegradable, sustainable, and environmentally friendly. (Source: Debate over Chemical and Organic Fertilisers).

Chemical fertiliser (also called inorganic, synthetic, artificial, or manufactured) have been refined to extract nutrients and bind them in specific ratios with other chemical fillers. These products may be made from petroleum products, rocks, or even organic sources. Some of the chemicals may be naturally occurring, but the difference is that the nutrients in chemical fertilisers are refined to their pure state and stripped of substances that control their availability and breakdown, which rarely occurs in nature. Repeated applications may result in a toxic build-up of chemicals such as arsenic, cadmium, and uranium in the soil. These toxic chemicals can eventually make their way into your fruits and vegetables and long-term use of chemical fertiliser can change the soil pH, upset beneficial microbial ecosystems, increase pests, and even contribute to the release of greenhouse gases. (Source: Debate over Chemical and Organic Fertilisers).

Fertiliser use and agricultural production: Australia 

The above chart demonstrates the rise in agricultural production over the last three decades and the increasing use of fertiliser inputs (ie. nitrogen, phosphorous and potassium shorthanded as ‘NPK’) to achieve that level of real production. This provides an indication of the enhancements in production due to fertiliser, whilst acknowledging that other factors such as better herbicides and insecticides are also making a contribution. (Source: IAMA). 

If you're interested in reading about fertliser use in Australia, and the history of, see this link.

So now we know our fresh produce is grown in fertilised soil, but whether it is grown in chemical or organic fertiliser, we may not be entirely certain of. What about other toxins like pesticides, antibiotics and hormones? According to Better Health Victoria chemicals such as pesticides, antibiotics and hormones are used in plant and animal farming to boost production and ensure adequate food supply. (Source: Better Health Victoria).

What can I do?

• Buy unsprayed or organic produce
• Grow your own and use organic repellants
• Get to know your local growers
• Identify the fruits and vegetables with the highest pesticide load
• Buy produce from farmer's markets
• Wash your fruit and vegetables before eating and dry well with paper towel - dispose of the paper towel

Next blog post...Pesticides, Antibiotics and Hormones in Farming.