Across northwestern Wisconsin, farmers in four local watershed councils volunteered to participate in a light contest aimed at turning heads and crudely measuring soil biological activity.
The Soil Your Undies challenge is pretty simple: Bury a pair of underwear in the spring in a field, then let soil microbes work on them for 50 to 60 days. Cotton in underwear, being a natural fiber, is able to decompose quickly at that time, but they need a lot of microbial activity to break down. Fortunately, we’ve had a bountiful harvest of some super dirty Hanes.
Between May 25 and June 17, 30 pairs of underwear were planted in 4 counties. Those pairs were excavated between July 22 and August 3. Field planting history and tillage were all noted at planting time.
Unfortunately, a couple were lost; the fields look awfully different after 60 days of growth, and our markers were very hard to find in the 8′ corn. Imagine me, crawling through the corn rows on my hands and knees looking for little pink flags and idly checking “before” photos of the field to try to triangulate the location. To my credit, and more to the credit of the farmers, we found almost all of them.
More than one farmer called out halfway through the challenge to say “it hasn’t rained, the underwear will be as fresh as it was when we buried it.” Those farmers were all surprised at what their land did even during a dry season.
However, humidity was very important. Dry fields without live roots in the soil decomposed less cotton as shown by the test plots at Mann Valley and Horse Creek. While the fields under irrigation, even with a little tillage, the white tights had been torn apart.
Every pair of shorts we’ve released has told a really interesting story. In general, fields that had a longer history of fallow and reduced tillage had better separation than those with more tillage.
For example, the River Falls FFA test plot has been uncultivated for 2 years, while the Tim Jennings field, less than a mile away, has been uncultivated for 8 years. Of course, there were far fewer underwear left in the 8-year-old field. Mike Wold in Dunn County has been mostly idle in his fields for 20 years, and his couples were some of the most degraded. However, one pair in Pierce County took the cake. They were buried in a field that has been in the CRP for most of the past 40 years.
Another lesson: poop spoils the insides faster. Sigh. The jokes keep coming. But in fact even with more tillage and less variety of crops in the rotation, farms with the inclusion of cow manure had much more spoilage. This was not so true for incorporated turkey litter or even pig manure.
A major comparison occurred at Cormican Farm in Glenwood City. Andy and Don planted underwear in two fields very close together. Both were fallow and both had cover crops the previous year, but in one field, their cattle had grazed through the cover and in the other, the covers had been chemically cut in the spring at a height of two meters. The wear in the grazed field was much more degraded than in the field without cattle access.
So some internals were more damaged, why does this matter? In short, healthy soil is more resilient to weathering and can hold more nutrients than inert soil. How does this work? Mainly soil structure and water absorption. Organic matter, such as roots and microbial colonies, create structure by literally gripping the soil and absorbing water instead of allowing it to pass over the surface. This makes healthy soil much less likely to erode during rains or be blown away by the wind.
Of course, retaining that moisture gives crops a larger moisture bank to draw on during drought. Healthy soil microbes also unlock nutrients as they break down organic matter, providing more fertility for crops.
Is it as simple as it sounds? Of course not.
Soil scientists note that biodegradation may be slower in some very healthy soils due to higher fungal activity. Soil fungi are great for soil structure and plant nutrient availability, but are a slow decomposer and take longer than soil bacteria to break down material.
Fortunately, more scientific measurements can provide a ratio of fungal activity versus biological activity in the soil to people who really want to take a closer look under their dirt. For the rest of us, we can use Hanes to get a general idea of how our soil is doing.
A farmer who applied fungicide had a lot of decay and maybe killing the fungus made more room for bacterial colonies. Another that used a lot of biologicals and had fantastic looking crops and extremely high biological measurements through testing, had very little internal breakdown. In short, burying offal is not a perfect test of soil health. And this is not an exact science, but in general, it has shown general trends that more soil health practices are associated with more decomposition.
Does more viscera breakdown translate into better crop yields? We don’t know yet. We will try to do some rough tracking at harvest time. But of course, yield depends on hundreds of different factors, especially rainfall. Does more corn mean less offal? Like a lot of pulled underwear, the well of jokes on this subject is endless.
Tara Daun is the watershed coordinator for four farmer-led watershed councils in northwest Wisconsin. More information on the project can be found at farmerledwatershed.org or by following @farmerledwatershed on Facebook.