Some research indicates that industrial farming policies can degrade the soil and add to erosion. Luckily, researchers in Australia have come up with a quick, easy and novel way of measuring soil quality – just bury your underwear. By James Teo.

Armidale, Australia. May 2021. According to researcher Oliver Knox PhD, a senior lecturer at the University of New England (UNE) in New South Wales and head of the School of Environmental and Rural Science at UNE, soiling your underwear is a great way to check the health of soil.

As the health of soil depends not just on its composition, but more importantly on the health of the bacteria and bugs that live in the soil, measuring the way they help rot down buried organic matter (like cotton underpants) is a great way to check if the soil is good or not.

“We decided to start an experiment using cotton as a soil health indicator at an industry conference, after hearing about a similar program in Canada,” he said. He reasoned the number of healthy bugs in the soil should be in direct relation to the way the cotton (underpants in this case) rots away when buried in the soil. He was right.

Dr. Cox’s experiment turned out to be a winner. He discovered that pure cotton briefs, dug into a variety of soils, proved to be the perfect measuring device for cotton-rotting bug population, and hence soil health. So did lots of his fellow researchers, farmers and more. "We suddenly had 50 pairs of underpants delivered to the conference in plastic bags," he said. 

Buoyed by the success of this easily understood yardstick for soil health, he became the go-to man for DIY soil measurement. "Farmers were over the moon about this (approach) now that they had looked at their soil biology and their soil health — all based on the degradation of pairs of underpants," he added. "We had (feedback from) people from as far away as Christmas Island, Perth, Australia’s Red Centre, way up north, down south, all through New South Wales and Victoria and into Queensland – all using underpants measuring.” Cox described the response to his ideas as: “phenomenal – it was amazing to see how people joined in."

Knox, explains that because cotton is made of cellulose, it is ideal as a foodstock for microbes and other bacterial decomposers that live in healthy soil. The greater the number of microbes, the healthier the soil. A healthy soil helps produce better plants and can accelerate growth and bolster resistance to disease. So the quicker the pants break down (or rot away), the better the quality of the soil, he reasoned.

So if, after the pants are buried, they look like they have been eaten by rodents and are full of holes when they are dug up after a few weeks, the soil is good. It they just look dirty – but are in overall good and original condition – the soil lacks nutrition, meaning farmers need to attend to its health. If there is not much left of the pants, then the soil is healthy and teeming with activity, and there would be no need to get the knickers in a knot over soil quality.

The initial trial called on 50 farmers to bury their underwear in their fields, and the resulting publicity spawned a frenzy of underpant soiling. “Not only did they (bury the cotton undies), but they started competing with each other,” said Knox. “They started comparing, saying things like: ‘My soil is better than yours because I have more degraded pants’.”

Soon, hundreds of people – from farmers to schoolchildren – were joining in, burying cotton underwear in their back gardens, schools, local allotments ready to be dug up a couple of months later. It grew into what Knox and a bunch of cotton growers called the Soil Your Undies Challenge. It has spread to New Zealand and even further afield too.

And the spread of the trial meant that a much wider range of results started to come in, allowing Knox and his team to gather some hard data and draw conclusions from the outcomes, holed or not.

Although many of the farmers buried underwear in heavily-used soil, it often turned out to be in very good health. “Many of the pants (buried in heavily used soil) were wonderfully degraded, with nothing much more than just the elastic left,” he said. “They indicated that the soil was better and healthier than a sample taken from  undisturbed soil on a nearby riverbank.” - which many had guessed might be teeming with microbes, and overall healthier. But no, these pants were much less rotted down.

“This was probably due to more plant material being returned to the (farmed) soil at harvest, and also to more watering than the soil got on the riverbanks,” he explained.

And boggy areas, which might be expected to be rotting paradises, turned out to be really quite unhealthy in terms of microbes. “Pants buried in the paddock (field) drain area hardly degraded at all,” noted Cox. “It seems too much water keeps the pants anerobic, and there is also little plant residue there either, to act as a fungus starter. So overall, there was much in the way of soil health in the soil near a field drain.”

This, said Cox, was against conventional thinking. “Sometimes what you think is going to happen doesn’t always happen. We conformed that for healthy soil, you need an array of organisms. Plus the presence of water, temperature and a mix of different organisms.”

And the best way to check? Soiling your underpants, of course.