Subsoil Moisture at Long-Time Low in Parts of Indiana

Soils that usually hold water in profile are bone dry.

John Zupancic, Morgantown, was able to dig through the four soils pits contest organizers wanted for the Area VI soils judging contest near Morgantown in Morgan County. But instead of striking oil, gold or just water, he struck dry dirt. Even four feet deep in soils that traditionally are moist in the subsoil this time of year, he turned up dry dirt. FFA and 4-H soil judgers didn't have to worry about getting their feet dirty as they judged pits last week.

Soils judging is a fall activity. Many schools hold invitational contests. Even after some rain during September, most of the contests have featured pits that were so dry they present challenges to judgers to evaluate them properly. Textures of subsoil are especially hard to determine in super-dry soils. The accepted method for determining soil texture in the field is to pull out some soil, wet it lightly, and rub it between your fingers. In high-clay content subsoils that are very dry, the soil comes out in chunks that take a while to break down to the form that you can determine how well they hold together when pushed between the fingers.

"This is probably the driest soils in this area have been in the subsoil in 20 years," says Chris Parker, Morgan County Extension ag educator who helped locate the site for last week's soil judging contest. He also lined up Zupancic, an area farmer, to dig the holes for the judging event. Soils judging contests are wrapping up in all 10 judging districts. The state contest for 4-H and FFA judgers will be held in Jackson County on Nov. 3. Qualifying teams in the top 20%of all teams in each area are eligible to participate in the state contest. The top five-scoring FFA and top –five scoring 4-H teams at the state contest are eligible to participate in the National Soils Judging Contest, hosted in Oklahoma City early every May.

Morgan County, in south-central Indiana and about 35 miles southwest of Indianapolis, features a variety of soils. That's partly because the most recent glacier that leveled and smoothed out much of Indiana didn't reach into Morgan County. Soils there can have fragipans, dense till and/or bedrock, all of which limit root growth. But there are also thousands of acres of highly-productive farmland in the western part of the county, surrounding the Eminence area.

Three judging pits out of four at last week's contest featured clay texture in the subsoil, a fairly unusual feature to find in most Indiana soils, especially those that are farmed extensively. Most till and loess upland soils in that part of the state are moderately clay in the subsoil. The amount of clay in the soil can determine how both water-holding capacity, and how quickly water moves through the soil.

Often soils with clay in the subsoil are sticky. "There were very hard because it was so dry down there," says Phil Owens, a Purdue University soils specialist who helped evaluate contests to determine official answers for the soils judging competition.

High-clay content soils often take on a shiny appearance. It's usually evident if you moisten a sample of high-clay soil, then split it in two and examine the smooth face in the sun. However, even on a cloudy day, some of these Morgan County subsoils had a slick look to them, due to the high clay content.

The bottom line is clear- if you dig postholes or basements in the next few weeks, don't expect to find moisture, especially in central and southern Indiana where rainfall continues to be hard to come by. If you're building a basement, now can be a time to make a big mistake. Just because the soil is dry now doesn't mean it will be when more natural weather patterns return. Consult a soil scientist adept in evaluating the soil conditions before deciding if a basement is appropriate on your building site.

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