Darren and Brian Hefty talk about potassium and the role it plays in soil fertility. They explain solutions being short on potassium, as well as discuss how to calculate how much potassium should be added to reach maximum soil fertility.
Some observations from my farm. With K at 1.2%, CEC ~35 in 2016, I calculated I need to add 400ppm to reach the 4% target. Couldn't afford that so since 2016 when I tissue tested 10 weeks on corn and saw shortage of K during growing season, I've reached 2.5%. Doing that I've seen my R1 ear leaf tissue test N levels improve 20% on my ph 8.0 ground and 10% on ph 6.0 ground (over 3.5% in 2019, assuming this will go right to the ear at this point with good moisture during fill). This comparison was done from wet year 2016 to wet year 2019. The exciting thing is in 2019 I used 25% less N because I was tired of paying for N and not getting even close to 1#/bushel utilization. With my K levels at 2.0% or more at R1, I"m moving to a grain removal strategy on low income years, and working to build on high income years, while at the same time keeping N lower than 2016. On a dry year (2018) K was still short most of the season, so getting to 4% would be nice. Overall by improving K I think my N utilization is much better, I can afford to work on improving micros and P as well. Great work from the Blacklands of Central Texas. I would have never gotten this information otherwise.
Neal Kinsey talks about correlation between soil ph and potassium. His statement is that if soil ph is 6.5 or above, soil coloids are saturated and can't retain applied potassium. Is that true for all soil types? What does your experience tell you?
Thanks for the information! My dad and I visited one of your winter workshops this January and decided that we should start banding our fertilizer. My question is that if we wanted to reach at least 4% base saturation K, should we consider broadcasting if we were to apply large amounts of K? I'm assuming that we wouldn't want to put out hundreds of pounds in a small band that might be difficult for plants to utilize in the future. Thanks!
You talk about having at least a 4 for a base saturation % of K. We have seen over the past few years that our soil tests come back with a 1 or 2% base saturation K in our 200+ bu/ac corn fields. We are not seeing any benefit. Also, the U of M guidelines state that no more potassium is needed at a soil test level of 200+ ppm at any yield goal.