About Your Fields, August 27, 2018
In this issue:
1. Are Your Soils O"K" for Next Year?
2. What's Next?
Are Your Soils O"K" for Next Year?
This week we will take a look at potassium often called by it's chemical symbol K. Potassium is one of the three macro nutrients necessary for crop production. In the past I feel we have not paid as much attention to this nutrient in corn production and focused more on soybean needs for potassium. In corn we paid much more attention to phosphorus needs which we looked at last week. However, in the last few years we have found that phosphorus is more important in beans than previously thought and that potassium is critical for the corn plant later in the season. As you can see in the diagram below potassium is needed later in the growing year.
Potassium helps open stomates in the plant, which regulates the exchange of CO2, water vapor and oxygen. Potassium helps with root growth, building cellulose and aids in photosynthesis and food production. One thing that I find interesting, is that due to its ability to control the stomates potassium improves drought resistance, but if you are in a drought and you have clay soils potassium can be tied up. Another factor to look at is if you are short in potassium you could antagonize other vital nutrients like phosphorus, nitrogen, boron and magnesium as shown in the diagram of Mulder's Globe below highlighting potassium.
A good soil test level of potassium is 350 to 400 lbs. per acre. If you have 220-bushel corn, you will remove 66 pounds of K2O which is what potash is. If you have 250-bushel corn you will remove 75lbs of K2O. 70-bushel soybeans will remove 98 lbs. of K2O and 85-bushel soybeans will use 119 lbs. It takes 4 lbs. of K2O to raise your soil test 1 point, so if you have 220-bushel corn and 70-bushel soybeans you could in theory take 41 lbs. off of your soil test if you do not put adequate potash on your fields. If you have any questions talk with any of the agronomists here at Akron, and we can help you make a wise decision on how to spend your fertilizer dollars.
As we come to the end of August harvest time comes closer, but before you go out and fire up the combine you have to go eat Sam's fried fish at the Akron Services Fall Agronomy Day. Join us on September 4th at Ben's at 4:30. Come a little early and visit with some of the company representatives who manufacture the products that we are testing this year. At 4:30 we will start our program featuring Dr. Greg Willoughby of Helena Agri-Enterprises, company reps from DeKalb/Asgrow and Credenz, as well as a presentation about what we have seen in our plots. We hope to see everyone there.