Mid-May and 77% of corn acres are in the ground

Encyclopedia Article

By R. Elmore and L. Abendroth

14 May 2007 -

Iowa producers planted nearly 900,000 acres of corn per day last week. According to the National Agricultural Statistics Service (NASS) Progress Report, published 14 May 07, 77% of Iowa’s corn acreage is now planted (refer to NASS link below). This is 5 days behind the 5 year average. Yet there is no need to change hybrids or cropping intentions.

Iowans planted more than 3 million acres of corn during the 3.8 days last week deemed suitable for fieldwork (refer to Iowa Crops & Weather link below). At this pace, the majority of Iowa’s remaining corn acreage could be planted this week. Every day matters as research has consistently shown yield reductions to occur when corn is planted during the second half of May.  

Regions exist across the state which are significantly ahead or behind compared to the statewide average. For example, northern and east central Iowa has 85 to 92% of the corn acreage planted. These areas had more than five days last week suitable for fieldwork. Contrast that to south central (37% planted) and southeast (55% planted) Iowa and it is clear that they are lagging behind the rest of the state. Yet forgoing any major rain events, significant progress can be made in these areas as well as other parts of Iowa to allow for the majority of the corn acres to be planted by this time next week. 

The amount of acreage planted per day was slightly less last week in comparison to the week before, although this is not surprising since the first fields to be planted were likely those that were better drained. Iowa fields that are yet to be planted are most likely wetter and will require more time to dry; some wet pockets within fields may not be planted at all this year.  

We are in the time of year where yield potential decreases with each day that passes. Although the yield reductions can amount to one to two bushels per day past May 15th it is not necessary to switch corn hybrids. Hybrids can still perform well agronomically, although grain may require extra drying following harvest if moisture content is higher than normal.  

Thirty-six percent of Iowa’s corn was emerged as of May 13th according to the NASS report.  Iowa State University Field Crop Specialists have reported that the most advanced corn across the state is in the two-leaf stage. Early emerged corn in general looks good. Although some areas exist that have had variable emergence and low plant populations; these need to be assessed to determine if replanting is necessary. An ISU resource on determining when to replant is the Corn Planting Guide (https://store.extension.iastate.edu/Product/pm1885-pdf).

Crop Reports: 

NASS Crop Progress report

Iowa Crops & Weather (USDA-NASS) report from the Iowa Field Office: http://www.nass.usda.gov/Statistics_by_State/Iowa/

Iowa State University Agronomy Extension Corn Production