A look inside the world of soil judging
Slide 1. The 2013 collegiate soils competition took place in Platteville, WI, a farming community nestled in southwestern Wisconsin’s driftless area—a hilly region that was bypassed by the last continental glaciation roughly 10,000 years ago. The competitors’ charge is two-fold. First, they must scientifically classify the soils they examine into different types, similar to how biologists assign plants and animals to different species. Then, they use this information to make management decisions about the soils. How much wastewater can the soil take and at what rate? What are the limitations of the soil for building roads and basements? This year, contestants had to bundle up. Competition begins promptly at 8 am every day, and spring in Wisconsin is chilly.
Slide 2. The contest takes place in large pits, where competitors study the soil under a strict time limit. What are they looking for? First of all, they have to figure out where each layer of soil, or soil "horizon," begins and ends—a critical task. Because every subsequent decision the students make is based on the soil found in each horizon, misjudging the boundaries between horizons means possibly botching the entire competition.
Slide 3. One soil property the contestants judge is color, which indicates what the soil is composed of. Soils high in organic matter are darker, for example, and soils rich in iron are red—unless the iron has gone through a process called depletion, in which case the color is grey. Students identify the colors by comparing soil samples with a series of color chips in a color book similar to the kind artists use.
Slide 4. Soils are also made up of particles that fall into three size ranges—sand, silt, and clay—with sand being the coarsest and clay the finest. The percentage of sand, silt, and clay drive the expected physical and chemical properties of soil. Using only their hands, competitors must determine the percentage of each particle type in the soil within plus or minus five percent of the correct answer.
Slide 5. Using a device called a clinometer, contestants examine the slope of the land adjacent to the soil pit and decide what the “slope profile” is: For example, is the soil pit located at the summit of the slope, on the backslope, or at the bottom, or toeslope? Determining the slope profile helps the students decide whether the soil is susceptible to erosion, sedimentation, or neither. This, in turn, gives them an idea of the soil’s past and future.
Slide 6. Something else contestants watch for are streaks or blotches of color within the soil’s dominant color type. These streaks of contrasting color, called mottles, can develop when a soil is underwater long enough to deprive it of oxygen. One type of mottle, called a depletion, is an especial indicator that the soil probably shouldn't house a basement.
Slide 7. During their undergraduate careers, most soil judgers will experience bitter cold, driving rain, flooded soil pits, and other adverse conditions that can make it difficult to describe the soil properly. Wooden pallets help keep competitors from sinking into the mud. But water can also cover features of the pit that are needed to understand it fully.
Slide 8. Soil judging contests are watched over carefully by “pit monitors”—usually volunteers from the host school, which is barred from competing. The monitors act as timekeepers to ensure everyone gets equal time in the pit, prevent cheating, and pull people out of the mud if they get stuck.
Slide 9. Once each team member has collected data on soil texture, color, and other properties, the individual contestants must come to a consensus on their description of the soil. The collaboration can be difficult, but it’s also satisfying and fun. Many soil judgers enjoy the opportunity to learn from their more experienced teammates, and learning to work on teams is a skill most college students don’t get to develop in other ways.
Slide 10. The team with the highest overall combined score takes home the coveted Soil Judging Trophy, a traveling award that carries all the names of the winning teams from past years.