Thursday, March 25, 2004
Early planted corn stands: is pretty the best?
We've had a significant portion of Minnesota corn acreage planted prior to May 1 for the past two years (2002 and 2003). In both years, plant stands have not been ideal - spacing between plants has not been uniform and final stands have been lower than expected. Yet both years have been excellent corn production years for Minnesota growers. The state average yield was a record 157 bushels per acre in 2002 and an impressive 146 bushels per acre in 2003.
When corn is planted later, there are fewer days that the seed lays in the ground because soil temperatures in the seed zone are higher. Plants will emerge in 5 to 7 days when planted in mid to late May.
Because soil temperature is so marginal in late April with respect to the temperature necessary to promote germination and emergence, small differences in soil temperature can cause uneven emerging plants with slow growth rates in mid to late May. Soil temperature differences in the seed zone occur because of differing water conditions and residue pieces on the surface, both of which cause the soil to warm more slowly. Uneven emerging fields may not be as pretty to look at as are fields planted later that emerge more uniformly and appear to be growing faster.
Uniform stands (both spacing between plants and time of emergence) are important to give all plants equal competition to water and nutrients. However, non-uniform stands are productive and profitable stands because late emerging plants do contribute to yield. Yields from corn stands with late emerging plants are given in the Corn Planting Newsletter (4/15/03) at http://www.corn.umn.edu.
There will be years again like the past two where stands will not be as good as growers intend. But these early-planted stands (lower than desired populations or uneven emerging plants or both) have a higher yield potential than do the later-planted stands that emerge more uniformly and appear to grow faster. Early planting sets the stage for high yields and the greatest profitability (see the Corn Planting Newsletter cited above for the relationship between planting date and corn yield in Minnesota).
There are two planting windows in Minnesota. The first is between April 15 and May 5. Then there is a higher probability of rainfall that stops field work. The second window for planting begins about May 15. Times and durations of these planting windows vary every year, but the pattern is the same. For maximum profitability, don't miss the first planting window!