A bit of soil fun in the classroom

Remember the old saying, ‘time flies when you’re having fun’? Well I don’t know if with assignments, lectures and intensives the Cotton Production students here at UNE would say they were necessarily having fun, but the eight weeks since we buried two pairs of cotton underpants as part of the #soilyourundies campaign certainly passed quickly for me.  

We started this process to do a few things. Firstly, to get our students engaged in an CottonInfo experiment and strengthen their connection to the cotton industry.  Secondly, to make them consider experimental conditions, ways to reduce environmental influence and set a hypothesis and, finally, to have a bit of fun

#soilyourundies

burying our pants

So what’s the point of the #soilyourundies

The premise for the experiment is relatively straight forward. Cotton underpants are made of cotton! Seems obvious, but the cotton fibres in the pants are made of cellulose, which in turn is made from hundreds of glucose molecules all strung together as a polymer. The way in which cellulose breaks down in the environment has been used in the study of fungicides, the longevity of fabrics and in environmental research, but most of this has relied on specialized cotton strip assays.

What these assays have taught us is that there are a range of cellulolytic enzymes involved in the break down of the cotton and that these enzymes come from a range of soil microbial organisms. So, by burying a pair of cotton underpants (rather than a cotton strip) 5 cm deep in the soil, leaving them for 8 weeks and then digging them up you can gauge by the amount of degradation as to whether your soil is microbially active. If we bury several pairs of pants you can start to consider if system management, soil types or land use areas show differences in their microbial activity in your garden or on your farm. Who knew you could learn so much from your pants?

So what did we find?

Well when we started we had two similar soils from different areas. One was from a cropping enterprise and the other was recently collected from an uncropped area near a river. The students hypothesised that the uncropped soil would likely show a higher level of microbial activity. They also decided to degrade our pants in a glasshouse so that we could reduce environmental influences. The pants were buried and the tubs of soil and underwear watered every week for 8 weeks. What we found was of surprise to us all, but even this was useful. 

Based on the state of our pants we rejected our hypothesis, but even this made us ask questions about whether we should have nutrient tested our soil before we started. After all, even microbes need a balanced diet. It also made us consider whether we should have given some consideration to pH or salt load in the soil before we started and this got us talking about how we might remediate these issues. Finally, some pondered as to whether the soil was just lacking some of the microbes needed for cellulose degradation, which again got us talking about how we might return or encourage recovery of the biology of our soils. 

So we learned a lot, we had some fun and we’d encourage anyone who’s interested to #soilyourundies.