Crop Condition
Both corn and soybeans have emerged across
most of central and north central Iowa. Corn ranges from V2 to
V5. Soybeans are from VC to V1 stage. Soils are completely
saturated in many areas. Weekend rain storms triggered very
serious flooding and caused even more soil erosion.
Replant Yield Expectations
Corn planted in mid-June (6/10-16)
provides 65-70% of relative yield potential. Soybeans planted in
early June provide 81% of relative yield in northern Iowa and 91%
of relative yield in central Iowa. Soybeans planted in mid-June
provide approximately 60% of relative yield potential for both
northern and central Iowa. Sources: Corn Planting Guide and
Soybean Replant Decisions.
Nitrogen Losses
N loss is certainly a concern to farmers in light of
the heavy rains we’ve received. Dr. John Sawyer reminds us that
the degree of leaching or denitrification depends on several factors
such as the percent of nitrogen in the nitrate form, the duration of
soil saturation, and the amount of water that effectively moves
nitrate through the soil profile. Dr. Sawyer wrote “Estimating
nitrogen losses – early spring 2007” for the May 14, 2007, ICM
Newsletter. In his article he notes that University of Nebraska
research found that denitrification losses were roughly 10% of
nitrate-N when soils were saturated for 5 days and 25% loss when
soils were saturated for 10 days. His article also discusses
estimating nitrogen losses and provides an example. The bottom
line is that some fields will likely need additional nitrogen.
Pesticide Use Near Rural Acreages
ISU Extension staff write the
Acreage Living newsletter for non-farming rural residents. The
June newsletter includes an article called, “Pesticide Applications
in the Neighborhood.” The article discusses why pesticides are
used, how to improve relations between farmers and acreage
owners when pesticides are being used, and pesticide drift.
Long-Term Weather Averages
Occasionally we all are looking for
the average rainfall, average temperature, first frost date, or any
number of other long-term weather averages. These can be found
on the ISU weather page under Iowa Averages.
To Learn More...
If you would like additional information on the above topics or have other crop-related questions, contact Field Specialist John Holmes.
Additional Sources
Previous 2008 Issues
2007 Issues
2006 Issues
2005 Issues
2004 Issues
Crop news from other Iowa field specialists