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How Healthy Is The Soil On Your Farm? 'Soil Your Undies' To Find Out

LULU GARCIA-NAVARRO, HOST:

Question - for the sake of the environment, are you willing to soil your undies? Before you lunge for the radio dial in disgust, I should explain we're talking about burying cotton underwear as a way to test the health of your garden's topsoil. In Australia, dozens of farmers have taken the Soil Your Undies Challenge. Oliver Knox helped organize the effort. He's a senior lecturer at the School of Environmental and Rural Science at the University of New England in New South Wales.

OLIVER KNOX: So these farmers take their pairs of pants out into their field and dig a shallow hole - literally, 5 centimeters deep, so the - you know, the depth of their fingers. And they lay the pants down flat, cover them up. And then they go back eight weeks later. They dig them up, and they're looking for degradation of the cotton, the breakdown of the pant. So in a nice, healthy soil where the soil biology is both diverse and active, all they'll get back will be the elastic waistband and the poly cotton stitching because the bacteria and the fungi in the soil have really gotten to work on that cotton fiber and broken it down into the sugar that it's made of and consumed them.

GARCIA-NAVARRO: The tasty cotton underwear was actually supplied by Knox and CottonInfo, an Australian industry group. Eight weeks after sending 50 pairs of undies to 50 farmers, the results came in.

KNOX: Fifty of these little Ziploc bags came back with soiled underpants, and it became a real competition between the farmers. You know, my soil's better than your soil because my pants are more degraded. And it was just wonderful to see them sort of create that competition between themselves but also just to start that conversation around soil biology and their soil health.

GARCIA-NAVARRO: The Soil Your Undies Challenge began in the United States and Canada a few years ago. But when Knox and his colleague Sally Dickinson brought the project to their own country, they encountered an especially Australian problem.

KNOX: The protocol basically said bury the underpants and leave the waistband above the surface so you can go back and exhume them really easily. So the first pair we tried, we did that. And we went back, oh, within a few weeks, and the pants had gone, but there was lots of kangaroo paw prints around the hole. So somewhere, Skippy's out there running around the outback with a pair of tighty-whities, as they like to call them here. So after that, complete burial and a flag, so we knew where they were.

GARCIA-NAVARRO: Jokes about kangaroos aside, the Soil Your Undies Challenge is a low-tech, accessible way to gauge soil health and draw attention to the shrinking supply of the world's topsoil.

KNOX: Our biggest risk is probably erosion. And then as climate change gives us more severe and more unpredictable rain events, we always run the risk of erosion. Our topsoil is so important. You know, it's where a lot of our nutrition and our mineral turnover occurs, which is what our plants rely to grow on. So, yes, we've got a lot of fragility there - the risk from pollution. And I always throw into that mix as well, particularly in urban areas, you know, that risk from sealing of our soils - concrete, tarmac, the things - the houses, our infrastructure that we build on it. You know, we've sealed it up. We can't grow on that anymore.

GARCIA-NAVARRO: School teachers in Australia are also drawn to Knox's project, though COVID lockdowns have affected his work.

KNOX: Not being able to go out to school groups and do our usual extension, we decided we'd open up this Soil Your Undies as a citizen science and particularly, a school-based challenge. So last year, we basically got 207 pairs of pants out to community groups, 161 of which were schools. And they soiled their undies, and we exhumed them, and they sent them back to the University of New England and put images up on social media. And we just got a really nice feel for, basically, the state of our soils right across Australia. To get, I think, school kids engaged in thinking about what goes on in these soils - I think if we can stimulate an interest in them at that young age and encourage that, then I think, hopefully, we can see changes in the way that maybe we behave towards our soils and our landscapes and make our future more sustainable through them.

GARCIA-NAVARRO: That's Oliver Knox from the University of New England in New South Wales. Transcript provided by NPR, Copyright NPR.

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