Large difference in rainfall, crop progress in NW/NC Iowa

May 4, 2016 1:58 PM
Blog Post

We have had a couple nice days and farmers are looking forward to some predicted good weather. Farmers are taking this all in stride since many have been through this before.

There has been a fairly abrupt line of heavy rainfall/planting progress in the area. Areas east of roughly highway 4 have mostly completed corn planting and have about 15% of the soybean crop planted. The area west of highway 4 have completed about 35% of corn planting. Areas in western Palo Alto County and parts of Clay County have received about six inches of rain the last week of April alone.

There have been a few questions on the effect of planting date on final yield and the need to change corn hybrid maturity. So far, most farmers have not made any drastic changes in their planting plans, figuring that the predicted good weather will allow most to complete corn planting in a fairly timely basis. 

The following (Table 1) is some good information from a date-of-planting study that was conducted at the ISU Northwest Research Farm near Sutherland in 2010 and 2011. Information from this study and others like it show a gradual loss in corn yield from delayed planting, but it is not too drastic until we get into late May and early June.

This study shows about a 7% reduction in yield when planting date was delayed from late April to late May–or about 0.6 bu/day. Grain moisture at harvest was similar for all planting dates. However, the 2010 and 2011 seasons were relatively long growing seasons where a delayed planting date had less impact.

Table 1.  Date of planting and hybrid relative maturity study, NWRF. 2010 and 2011.

Planting                      DKC 4837      DKC 5509

date                            RM 98             RM 105


4/29                           188                 212

5/13                           176                 215

5/27                           172                 197