By Roger Elmore and Lori Abendroth
23 May 2008 -
Some fields planted to corn across Iowa have been setback recently due to crusted soils. Rainfall beginning yesterday and projected to continue through the weekend will help soften the soil surface yet some fields may not be able to recover fully. According to the most recent USDA-NASS Crop Report, 18% of Iowa’s corn was emerged as of last Sunday (18 May 08); this is approximately 40% behind normal. Since this last USDA-NASS report, we have had much more corn emerge and more is continuing to emerge.
Wet planting conditions coupled with fine soil texture, intensive tillage over the row, and heavy rains after planting result in a pulverizing of the soil surface due to a weakening of the soil structure. Subsequent drying results in soil crust formation. Photographs from field visits this week are posted on the Image Gallery of our website, these show crusted soils and the impact this has on emerging seedlings.
"Corn Emergence Problems Across Iowa" is also online at the Integrated Crop Management NEWS website and discusses the status of the corn crop and options available to producers with crusted soils.
Several scenarios are possible in these problematic fields:
1) Corn seedlings will be significantly delayed or not emerge at all. Seedlings will make an attempt to reach the surface as shown in some of the photos but at times to no avail.
2) Final populations will be reduced.
3) Variable plant emergence.
4) Rootless corn.
5) Reduced yield as a result of any or all of the above factors.
What can producers do?
1) Assess your fields by counting the number of emerged plants. Ascertain whether the seedlings struggling to emerge will reach the soil surface.
2) Use tools developed to determine yield potential and the likelihood of the need for a replant. Many are listed under Planting on our website.
3) Rotary hoeing may be an option for some but not all situations. Be aware that rotary hoeing often reduces plant stands 5 to 10%; this becomes even more given certain field conditions. Be certain to check seedling survival and effectiveness of the hoeing operation before proceeding too far into a field.