It’s been a wild spring, there is no doubt.  Cloudy, wet, cold conditions have kept many out of the fields. Growers should resist the notion that because they are planting late, they should cut back on starter fertilizer.  That small amount of fertilizer is just what the corn crop needs to thrive until roots can explore more soil volume to collect water and nutrients.  Phosphorus is largely immobile – it doesn’t move with water like nitrogen or sulfur can. The best way to get P into the plant is through root interception and there is no better way to promote that than planter applied phosphorus.

Often later planted corn will be put into warmer soils. Maybe not this year.  Cloudy, rainy, and cold conditions are keeping some soil temperatures low. Iowa State University professor Antonio Mallorino offers three points (click on the link below for the entire article).

1.Do not underestimate the value of starter for corn planted late, mainly in northern Iowa cold soils and with a shorter season.
2.Starter P will provide the most benefit with low or optimum soil test P levels and low pre-plant broadcast application rates. But do not expect much yield response if the two-year P rate for the corn-soybean rotation was applied last fall or this spring.
3.Starter N may also be beneficial, mainly without high N rates applied pre-plant or near planting in the spring and with corn on corn.

Bob Nielsen of Purdue University offers some insights about late planted corn. He says that early planting favors higher yields, but it’s no guarantee. Planting date and and yield are not strongly correlated because planting date is only one of a variety of factors contributing to final yield. It is widely accepted that relative yield potential decreases after some date like May 1. Maybe as much as 0.3% per day.

His advice is to get the crop planted in as timely a manner as possible by reducing tillage operations or other field operations.  Sidedressing N may be beneficial if you don’t have to wait for pre-plant application. Sidedressing is a lower risk if 20 lbs of N can be applied at planting.  Click on the link below to read the entire article.

 

References/links

https://crops.extension.iastate.edu/cropnews/2013/05/dont-underestimate-value-starter-fertilizer-corn-planted-late

https://www.agry.purdue.edu/ext/corn/news/timeless/PltDateCornYld.html