THERE is some evidence that the "book values" that have been used for many years to calculate the amount of phosphorus and potassium removed by grain during harvest may no longer be accurate for the crops produced today, according to University of Illinois crop scientist Emerson Nafziger.
"The economic and environmental advantages of matching crop removal to replacement with fertilizer nutrients make it important to have good removal numbers," he said.
With funding from the Nutrient Research & Education Council, Nafziger said a new project starting in 2014 may provide a better idea of how much nitrogen, phosphorus and potassium are contained in harvested corn, soybeans 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 many nutrient levels. Thus, we will need to sample widely in order to get a handle on removal," he said.
Nafziger said he hopes to get most of the grain samples needed for the study from individual producers across Illinois, with samples sent in right out of the field, when grain is stored or after it is delivered to the elevator. He added that the project will start looking at wheat samples first and said samples are currently being accepted.
"While we are hoping for many 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," Nafziger explained. "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 seed companies or other ag retail personnel encouraging individual producers to take part."
Results will be summarized by region, with no identification of individual cooperators. Samples will be collected throughout 2014 and 2015.
"With a large number of samples, we will be able to see how much variability there is in removal numbers and to generate better removal numbers for Illinois producers," Nafziger said.