A DESIRE for fresh produce all year round, whether it is in season or not, has prompted Tasmanian soil scientist Dr Bill Cotching to ask consumers if they understand the effect this has on our soils.
Based at Tasmanian Institute of Agriculture’s Burnie campus, Dr Cotching has been farming, researching and advising on soil management for 40 years and said food consumption was putting pressure on our soil resources.
Tasmania’s red soils are known to drain well, but like most soils, are susceptible to compaction, which can affect soil structure for years, even decades.
“Factories like to keep operating all year round, so farmers store some produce in the ground, like carrots and potatoes, for processing when other crops aren’t available,” Dr Cotching said.
Soil is a part of our soul.
Year-round processing might be good for the factory’s bottom line, but can have dire consequences for soil.
“Prevention is the best cure. No amount of tillage will reinstate [soil] structure,” he said.
Healthy soil includes organic compounds left by crops and plant roots, but constant harvesting means this organic matter does not stay in the soil and compaction occurs.
“When you compact soil structure, you squeeze air out and the microbes have a less hospitable space to live,” he said.
A compacted soil environment affects what the microbes feed on and the air available to them, which leads to them producing toxic compounds.
“Every soil and farming system has a different set of soil health benchmarks. Soil health is complex as it involves keeping the soil in place, good water supply and storage, organic matter in equilibrium, biological activity enhanced and nutrient fertility balanced,” Dr Cotching said.
Some farmers rotate crops or leave time between certain crops, like potatoes, and use the paddocks for pasture instead, while others use controlled traffic farming.
“Farmers can make a good alternative income from raising pasture. Some farmers graze in winter when feed stocks are low, but this compromises the paddock for the next crop,” Dr Cotching said.
Another alternative is moving vegetable production to soils that are less vulnerable to degradation, such as sandier soils, but this can increase the risk of erosion and organic matter decline.
“There are always trade-offs. Our farmers need assistance to keep producing the food that we eat three times a day,” Dr Cotching said.
“Consumers could pay more recognition to our soils as they are the conduit to most of human life giving energy. Soil is a part of our soul,” he said.
- This story first appeared in The Examiner.