PRST STD U.S. POSTAGE PAID OMAHA, NE PERMIT NO. 36
Section
A
Volume VIII, Issue 3
March 2014
The ground will benefit from warmer weather, but consistent temperatures above freezing are not mandatory to defrost soils. The scene above shows a frosty western Iowa farm.
Photo by Bruce A. Binning
Waiting for the thaw Ground still frozen but state climatologist says planting shouldn’t be delayed by Greg Forbes Living in Iowa may feel like being in an ice cube the last few months, but Harry Hillaker, state climatologist with the Iowa Department of Agriculture, said the persistent cold should not lead to delays in the planting season. Hillaker estimated that based on limited data, the deep frost in the soils may be gone by late March or into the first week of April. While the frozen ground may damper planting efforts, Hillaker said he believes the biggest temperature threat to farmers lies in the soil condition. When soil first starts to thaw, he said, it works from top to bottom, which means the top inch or two may freeze and thaw several times before deeper inches begin to defrost. “That layer that’s thawed is completely muddy and complete muck. It makes for a real mess,” he said.
He continued that because of that barrier, water cannot move into deeper soil depths and either pools or runs off. “The frozen layer down below will be the bigger issue,” he said. “Frost itself isn’t going to be the limiting factor as ground being frozen, just that the frozen ground beneath the surface will be causing issues with drainage.” Due to the depth of the frost, Hillaker said ideally, the frost would be gone before spring rains begin to fall. Most rainfall will run off and could lead to flooding, he explained. Hillaker explained that ground will benefit from warmer weather, but consistent temperatures above freezing are not mandatory to defrost soils. “The temperatures don’t even need to be above freezing if it’s sunny out. The ground can thaw even with temps below 20,” he said. “But the warmer it gets, the more it’s
going to help,” he continued, and added that the daily average temperature is increasing approximately half a degree per day. “The season is on our side right now.” He estimated (on March 5) that as soon as March 7, the top inches of soil will be thawed out. By the following week, a few more inches will be freed from winter’s grip. “It will be sloppy at first but will eventually get us in the right direction,” he said. While western Iowa may see conditions improve with plenty of time before the planting season, Hillaker said the northeast corner of Iowa is less lucky. He estimated that portions in northeast Iowa may have 20 to 30 inches of snow on the ground, or two to three inches of liquid moisture, as of Wednesday, March 5. He said a snow pack that deep will greatly increase the amount of time needed to defrost soil. Hillaker added that with the depth and
the northeast portion of the state entering winter with the highest subsoil moisture in Iowa, flooding and planting delays may be a large possibility. Although spring is rapidly approaching and cold temperatures remain, Hillaker said current conditions are no reason for panic in regards to the planting season. “Typically, farmers are not doing a whole lot of field work before the second week of April and it is rather unlikely ground will be frozen then,” he said. He mentioned that the most complications to planting season during the winter months occur when large amounts of snow falls before the ground is frozen, which was not the case this year. The main things to wait for now, Hillaker said, are consistent temperatures and cooperative weather. “The weather that’s yet to come will have a bigger impact on fieldwork than where it is at the moment,” he said.