We have had a couple windows of opportunity for fieldwork this spring. The week of April 10 to 17 saw a lot of fieldwork completed. Also, there was some fieldwork completed on April 23. I am referring to an area around Clay County and parts of Dickinson and Buena Vista counties.
However, the eastern part of my area has had less rain and has made some very good progress on planting. A large part of Kossuth and Palo Alto counties have nearly completed corn planting and have started on soybean planting.
So the wet/dry thing is kind of reversed this year–with the western part of my area getting too much rain and the eastern part getting about the right amount of rain.
A lot of areas around Clay County have had 4.0+ inches of rain since we kind of needed a rain, which was on April 18.
Will this planting delay affect corn yields? Iowa State University conducts some date-of-planting studies where we purposely plant corn at different dates to see the affect of planting date on corn yield and grain dry down.
A study at the ISU Northwest Research near Sutherland in 2014 and 2015 shows two different outcomes from a mid-April planting date compared to a mid-May planting date.
Planting date – 2014
bu/a grain moisture %
April 22 183 21.2
May 9 182 21.1
April–May difference -1 -0.1
Planting date – 2015
bu/a grain moisture %
April 15 223 13.3
May 18 204 14.9
April–May difference -19 +1.6
This data shows that a delay in planting can have a small affect, like in 2014, or a larger affect, like in 2015. A person needs to ask why the difference between the two seasons.
The two growing seasons were actually very similar in terms of total rainfall, temperature, and stress. However, the 2015 season was somewhat dry until some plentiful rainfall in mid-August. Logic would tell you that the late season rainfall would benefit the later planting date–but that was not the case.
However, you will notice that even the 19 bu/a yield penalty for delayed planting from 2015 outperformed both planting dates from 2014. The simple explanation might be that the 2015 season was a slightly better corn growing season than the 2014 season.
The take home message from this study and others like it sound like this. Even though we would like to have our corn planted by May 1, we can still achieve good corn production with good grain dry down with early to mid-May planting dates.