Hi, Jamie Patton with the Nutrient and Pest Management program! Let's talk a little bit about
prioritizing phosphorus and potassium applications in this upcoming year of high fertilizer prices.
So when we look at prioritizing nutrient applications, good decisions start with good soil
tests. So for a compliant nutrient management plan you're going to need soil tests that have been
collected within the last four years. However, this year, of any year, might be a good idea to
go back and think about testing even a little earlier. The potential return on investment
on our soil test this year is potentially very high. You'll see in that slide it's saying
that at 70 cents per pound of nutrient, which is the price give or take right now as I'm
making this recording, at 70 cents per pound of nutrient that soil test only has to save me
potentially around 20 pounds of nutrient application in order to justify itself. So
that potential return on investment of updating those soil tests this year is quite high and we
still have plenty of time after soils unthaw to get those soil samples collected, to the lab, and
get those results back so that we can make sound nutrient management decisions this growing season.
Once we have those soil tests back we can think about utilizing the test categories and their
probability response to prioritize fields for nutrient applications. So if I have a limited
amount of nutrients that I'm willing to purchase or a limited amount of manure that I have on hand
I might prioritize applications to soils that are testing in the very low and low category.
The reason for that is when we look at this table on the left-hand side, soils that test
very low have a probability of response to a nutrient application of greater than 90 percent.
What that means is more than 90 percent of the time if I apply that given nutrient to that soil,
I'm going to see a yield response. If I have a low testing soil, you'll see that
probability of response is 60 to 90 percent of the time, and that's still really good. Optimum
it's 30 to 60 percent of the time I will see a probability of a yield increase, so still quite
high but not as high as that very low and low testing soils. So if I'm prioritizing applications
of nutrients, particularly if they're limited, I might strategize and put those nutrients
on soils that are very low and low in the testing categories because I am almost, Almost,
ALMOST not necessarily, but ALMOST, guaranteed a yield response for applications to those fields.
In addition to looking at those soil test levels, I also want to consider soil pH. So I'm going to
apply nutrients to those fields that have a pH that are already optimum for my crop rotation. So
we know that soil pH can have a dramatic impact on nutrient availability. If I'm applying nutrients
I want to get my best bang for my buck, so I'm going to apply to those fields that have an
optimal soil pH I might also think about the land tenancy. So do I own or do I short-term
rent this ground? Since phosphorus and potassium applications are a long-term investment, not all
of it is going to be utilized here in this first year. We're going to maybe want to think about
applying these very costly nutrients to lands that I own so that I can continue to reap the benefit,
or get the higher return on investment over time, to those nutrient applications
versus those to the lands that I actually rent. I also want to look at fields and strategize and
prioritize those fields that have historically higher as well as consistent crop yields. Again
looking at that probability of yield response. If I know I have good soil, less compaction,
higher soil organic matter, and it isn't as droughty as some of my other soils I may want to
prioritize nutrient applications to those fields so that I get that return on investment. Also,
think about ongoing pest pressures. When we think about fields that have high waterhemp
populations, when we think about fields that have white mold, or ongoing pest problems,
or consistently have corn rootworm. I may want to move my nutrient applications to fields that
do not have those high pest pressures so that I can again get the most bang on for my buck
out of those nutrient applications. So a lot to think about, a lot to consider,
if I am limited in the amount of nutrients that I can apply. A lot to consider of where I want
to strategize, where I want to prioritize, those nutrient applications. But soil testing is the key
to helping me to start to make those decisions. So up-to-date properly collected soil tests,
and then looking at those fields that have very low and low testing soils, so are falling into
those categories, are going to be a good start at prioritizing applications this growing season