The following information was provided during a 2023 Strategic Farming: Field Notes session. Read further to learn more about this free program that takes place each Wednesday morning throughout the growing season.
Soil moisture conditions
Soil moisture conditions throughout the state have tended toward the extremes in 2023. Heavy spring rains in much of southern Minnesota led to soils being too wet early on, and lack of spring rains in central Minnesota have led to very dry soil conditions.
One of the University of Minnesota’s irrigation research locations in Becker, MN (Sherburne County) received 3 inches less rain in May and the first week of June 2023 compared to the same period in what was a very dry 2022. At this location, the first 10 inches of soil is very dry, but there is moisture lower in the profile.
After a crop’s stand is established, not only do the dry soil conditions favor roots growing deeper in the profile to mine water, crops can tolerate some early-season stress. Despite the lack of rainfall, at both the Becker and the Westport, MN (Pope County) UMN irrigation research locations, established crops have not yet been irrigated for these reasons. If hot, dry conditions continue, irrigation will need to take place in the next couple of weeks or producers risk the crop experiencing enough stress to impact yield potential.
In soils that were too wet early on, stand establishment can be reduced and waterlogged roots can reduce yield potential. For these reasons some farmers have replanted or at least gone through to break the surface crust. The moisture that is banked in the soil profile may be welcomed later in the growing season if it turns out to be a dry one again this year.
Deciding when to irrigate
The data generated by monitoring soil moisture sensors placed in irrigated fields helps in timing irrigation frequency and amount to one that is both most cost effective and beneficial for maximizing a crop’s yield potential and resiliency. As with any other input, there is a cost to irrigate, so crop producers are urged to dig a bit deeper into the soil profile than the top 6 inches to determine whether there is moisture in the profile that one could reasonably assume the crop will access.
Crop water demand changes throughout the growing season. In corn, the period of highest water demand is when the crop is getting close to tasseling (when there are more than 10 leaf collars); it is during this time that 0.7-1 inches of irrigation water (also depending on soil type and irrigation system capacity) is recommended when irrigation is warranted.
How are water tables looking after 3 years of very dry or droughty conditions in some areas of the state?
We are unaware of news that water tables are declining in irrigated areas, outside of some of the groundwater management areas designated by the Minnesota Department of Natural Resources. Some of these areas have had declining water tables and stream water levels for some time, declining more in the last couple of years. While water tables in other irrigated regions can get depleted when irrigators start running, which was the case in 2021 and 2022 when well levels during the irrigation season declined substantially and had well interference issues. However, those sitting under sand are quickly replenished due to the quick infiltration of spring snow melt.
Source: umn.edu
Photo Credit: GettyImages-oticki
Categories: Minnesota, Crops, Corn