Northwest Iowa Crop Conditions

Extreme rainfall variability continues to be the theme this season. Within the counties northwest of Storm Lake (NW Iowa), we found June rainfall totals varying from 5 inches up to 14 inches. Normal June rain fall for NW Iowa is about 4.5 inches, so some areas were over 9 inches above average. The northern 2 tiers of counties have remained wet all season as well as a growing wet area east of Storm Lake. Lower rainfall totals were found in southern O’Brien, eastern Plymouth, Cherokee, Buena Vista, eastern Wood bury, Ida,and Sac Counties. Areas that have escaped the big rains have mostly excellent crop conditions; areas with high rainfall totals have variable crops depending on drainage capacity.

The Big Sioux, Rock, Floyd and Little Sioux rivers all had major flooding as well as many smaller rivers and streams. Thousands of crop acres were flooded along these rivers, and many roads and bridges were closed due to the high water.

The corn crop is generally handling the wet conditions better than the soybeans, but neither crop can be completely saturated or flooded for more than about 5 days. Another concern with corn in areas that hadheavy rain is nitrogen (fertilizer) loss. Excessively wet, warm soils, increase the potential for N losses fromdenitrification or leaching. Corn that’s lacking nitrogen will turn yellow starting at the tip of the leaves. The corn in wet field could also be turning yellow just from lack of air to the roots.

The early planted corn will begin tasseling later this week which is ahead of normal schedule. This corn will start silking (pollination) next week. This is a time of rapid ear development, so stress (extreme heat) overthe next two weeks would reduce yield potential. Most of the corn that has not been drowned out looksvery good to this point.

It’s no secret that soybeans don’t like wet, saturated soil. Plants with “wet feet” for extended periods of timeturn yellow and grow slowly. We are seeing lots of soybean fields where the wet areas are turning yellow.These beans will be smaller and are more susceptible to diseases. If conditions dry out relatively soon they should still have good yield potential. The areas that caught less rain generally have better looking soybeans. Having good drainage is very important this season.

The grain markets are still looking for the bottom. We are hoping for some positive news on trade (trade war) to stop the market decline. Another negative factor, the national crop condition ratings are very good so far this season. There is no major perceived weather threat to U.S. crops currently, despite the flooding
issues locally