If the sun is shining and the calendar date for your part of Iowa lies on the early side of the range listed above, and if soil temperatures are in the high 40s or higher and climbing, checkout the five- to seven-day forecast. Plant corn if the forecast calls for more of the same. If, on the other hand, the five- to seven-day forecast calls for a good chance of cold wet weather settling back in for a while, keep the seed in the bag.
Soil conditions: Beware of soils that are too wet, sidewall compaction results
Mahdi Al-Kaisi addressed soil conditions for planting in ICM News a few weeks ago. Field-capacity soils at planting depth are ideal for corn germination and early seedling growth. Beware of soils that are too wet. Side-wall compaction stymies early seedling growth both below- and aboveground and reduces yield potential. Deeper compaction from planting, spraying and harvesting equipment reduces yields for years. Ensure that soil conditions are optimum at planting.
Seeding rates: Follow recommended plant populations for corn in Iowa
Optimum plant populations for normal Iowa conditions range between 34,500 and 37,000 plants per acre. Make sure to add in your normal attrition rate -- failure to germinate and/or produce a plant -- to compute your seeding rate. Attrition rates in our studies range from 3% to 7%. If your attrition rate is much greater than that, investigate the causes carefully!
One more note on seeding rates: if conditions are dry at planting and you expect them to persist, this is the year to be conservative when adjusting the planter. On your higher-yielding fields, plant on the average or high end of what you've done before or up to the range suggested in the last paragraph. On fields with less yield potential, I'd back off a bit on seeding rates. Remember though, modern hybrids are more able to tolerate stress than older hybrids.
Seeding depth: Pay attention to particular field conditions, adjust within reason
Standard corn seeding depth recommendations for Iowa are 1.5 to 2 inches. As we mentioned in the early March ICM News, this seeding depth allows for quick emergence and maximum emergence rates as well as proper root system development. As discussed above, soils with moisture levels at field capacity provide the moisture level adequate to germinate seeds.
Every decision that you make influences the size and scope for corn yields. From the corn hybrid you select to the seeding rate and row width you choose. Download our FREE report over Maximizing Your Corn Yield.