By Emerson Nafziger
There is some evidence that the “book values” that we have used for many years to calculate the amount of P and K removed by grain during harvest may no longer be accurate for the crops we produce today. The economic and environmental advantages of matching crop removal to replacement with fertilizer nutrients makes it important to have good removal numbers.
With funding from the Nutrient Research & Education Council (NREC) we are starting a new project in 2014 to try to get a better idea for how much nitrogen (N), phosphorus (P), and potassium (K) are contained in harvested grain of corn, soybean, and wheat. This seems like a simple thing to measure, but we expect that things like yield level, soil, crop variety, and growing season weather affect may nutrient levels. Thus we will need to sample widely in order to get a handle on removal.
We hope to get most of the grain samples we need to do this from individual producers across Illinois, with samples sent right out of the field or when grain is stored or delivered to the elevator. We’re starting now in hopes of kicking this off with wheat samples.
We will make it as painless as possible to send in samples, following the procedure below:
- Before harvest or at the time grain is stored or moved, the cooperating producer will send an email to NPKremoval@gmail.com to request a mailer. The email only needs the cooperator’s name, mailing address, and what grain (wheat, corn, or soybean) is being sent in. If the mailing address is in a different county than the field the sample comes from, please indicate what county the sample will be from.
- Prepaid mailers will be sent to the cooperator. The mailer will include a plastic sample bag with a label that has the cooperator’s name and crop, and will have only a blank to fill in with the yield level (estimated or measured) of the field from which the sample came (or will come.)
- The sample bag is sized to hold about 6-8 oz. of grain, which is all we need. The grain should be dry (at or below standard moisture) so it keeps well during shipping. Simply put the bag with grain into the mailer and drop it into the US mail. It will be addressed to go to a lab for analysis.
While we are hoping for a lot of cooperators, sample numbers will be limited by the funds available. That may mean limiting samples from an area where a lot of people volunteer to send samples. If a local elevator would like to send samples from trucks coming to unload, that would work, but would mean recording names, addresses, and yield levels at the point of collection. We would appreciate having seed company or other ag retail personnel encourage individual producers to take part.
Results will be summarized by region, with no identification of individual cooperators. We hope to collect samples over 2014 and 2015, and hope by getting a large number of samples to be able to see how much variability there is in removal numbers and to generate better removal numbers for Illinois producers.
Source: University of Illinois Department of Crop Sciences