Figure 1. “Tighty Whitie” demonstration, 2016 Soil Health School, Aberdeen, SD.
Soil is probably our most important natural resource. It is the foundation or factory for producing food. Without healthy soil, the system eventually fails; many civilizations in history have risen and fallen with the over-exploitation and demise of their soil resources. Soil offers several services for plant and animal production that include providing an anchor for healthy plant roots, offering essential plant nutrient uptake, supplying water storage, and cycling and storing carbon and other nutrients for improved and sustained plant growth in future years.
Improving and maintaining soil health is the ultimate example of sustainability. Without preserved and improved soil health condition, a food production system is not sustainable. Past and current soil management has greatly involved the inorganic side of the soil and plant system. Soil microbiology is minimally understood and many soil microbiologists recognize our limited understanding of the soil food web. For most soil health advocates, the importance of soil microbiology is recognized, although difficult to demonstrate, until now. A very simple demonstration using men’s underwear briefs is very effective in showing the results of crop production management on soil health.
Soil Health Demonstration: Tighty whities & soil activity
Soil microorganisms require carbon to survive. Men’s cotton underwear briefs contain high amounts of carbon. Therefore, briefs can be buried in the soil and retrieved later to see and evaluate soil microbiological activity and ultimately, soil health status. During the South Dakota Soil Health Coalition’s first Soil Health School in the Aberdeen and Ipswich areas, a “Tighty Whities” demonstration was conducted. The briefs were buried to about the waistline in the soil five weeks ahead of the school at 3 sites that included: corn with conventional tillage, soybeans under mulch tillage, and no-till soil currently with growing cover crops. Soil health school participants had the opportunity to extract the briefs and view the results of five replicates in each field. Results were revealing…to say the least.
A new brief was compared to one brief from each field. The first soiled brief in Figure 1 (second from the left) was from the no-till field with cover crops. Hardly anything remained of the brief, indicating extensive soil microbiological activity. The brief from the mulch (reduced) tillage soybean field (third from the left) had more material remaining when compared with the no-till/cover cropped soil, and the conventional tilled corn (for right) had the most material which indicated the least soil microbial activity. All 5 briefs buried at each site were weighed, with the results matching the degradation observed in the photo (Table 1).
Table 1. “Tighty Whitie” demonstration data set, 2016 Soil Health School, Aberdeen, SD
(Figure 1. order, left to right)
|Average Brief Weight
(grams/brief) 5 replications
|Control – non-buried||58.5 a|
|No-till soil with cover crops||28.4 c|
|Mulch (reduced) till soybeans||48.3 b|
|Conventional tilled corn||50.8 b|
|*Brief averages with different lower case letters are significantly different.
The Bottom Line
Soil microbial activity is a key soil health indicator. Crop producers concerned about too much residue when converting to no-till should know a cover crop/livestock integrated system can help utilize and manage plant residue levels. Most seasoned soil health producers recognize the value of the soil microbial kingdom and often refer to it as “the herd”.
For more information about soil health and the importance of soil microbiology, please visit the NRCS Soil Bacteria page.