Mud, slop and messy conditions have developed as the ground begins to thaw around Michiana. The US Drought Monitor shows much of Michiana in the abnormally dry category while to the north in the moderate drought zone. To the passerby, one might think that such a designation is crazy driving by standing water and sloppy livestock lots and gravel drives. The reality is that the area has received very little precipitation resulting in very low stream and tile flows and pond levels. Most hours have been below freezing since the start of the year for one of the coldest winters in recent years. As of Wednesday morning February 26, soil thermometers in northern Indiana show the 4” soil depth temperature to be 28-32 degrees F and most areas of northern Illinois or Indiana and Michigan with 12” soil depth thermometers showed freezing temperatures.
Many comments swirl of there being fewer insects due to the cold temperatures. In most cases the colder temperatures of 2024/25 will not have any impact on insect numbers. Corn rootworm eggs for example can survive temperatures down to 20 F and with the dry fall conditions, the cracks in the soil certainly provided opportunities for female beetles to lay eggs deeper than the usual 6 to 8 inches. Lack of significant snow cover for much of the winter and lack of soil moisture all aided in the soil freezing to > 12” depth in many locations. While it was a long cold spell for air temperatures, it was not lengthy with subzero temperatures during winter. Last week, NOAA maps showed likely the climax of icing for the Great Lakes which saw a relatively large bump in ice coverage for a short time and surpassed the averages since 1973.
What about the soil itself in terms of being frozen? Dr. Gary Steinhart, Purdue Agronomy Professor emeritus often referred to the West Lafayette area around the Purdue campus as “the freeze thaw capital of the world” relative to other areas of Indiana. His longtime study of soil compaction supports the fact that freeze thaw cycles do the most to help bust up soil compaction. However, most years, the soil does not freeze deep enough to have an impact on a tillage pan at 8” or deeper compaction from wheel traffic of larger equipment. The more cycles of freezing and thawing do help to break up soil. For Michiana, this winter has been a freeze and hold with no thaw cycles with a refreeze. However, the single freeze cycle that has occurred did reach depths to have value in breaking apart compacted soil.
While freeze thaw cycles do help to break apart soil compaction and loosen soil, the best means to year after year build soil tilth, keep soil compaction at bay and build soil organic matter to have darker soils, is to minimize soil disturbance, add cover crops to diversify crop species and control field traffic. Earthworms will do their job and the end result will be a healthier soil regardless of the outside air temperature.
In the meantime, continue to prepare to swing at flies and all of the other normal insects of spring, summer and fall. Stay off the soil as best as possible during the coming weeks as soil is most compactable when it is almost dry enough to get across but not quite. Hope that no big rain events come before the ground completely thaws with frozen ground limiting infiltration and percolation of water through the soil. The runoff and erosion would be very detrimental to soil health and water quality.