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ILSOYADVISOR POST
Calculate Crop Removal Nutrient Rates
September 19, 2020
With harvest almost upon us, its time to start evaluating crop nutrient removal rates in preparation for the 2021 crop. There are a lot of variables that can influence a crop nutrient recommendation and application such as market value price, application cost, soils supply, crop removal, etc.
As yields improve on both corn and soybeans so does crop removal of key nutrients. It’s time to evaluate if nutrient applications are at least matching or greater than what’s being removed by the crop year. If crop removal is greater than application over time, it will eventually catch up and result in lower yields and reduced soil test values.
The University of Illinois Agronomy handbook is a great resource for producers and agronomist to use as they evaluate crop nutrient needs. Remember that this information is based off years of research and is a baseline of where to start. I would recommend downloading the crop removal pages and reviewing the values for crop removal based off the crops planted over time. http://extension.cropsciences.illinois.edu/handbook/pdfs/chapter08.pdf
In recent years, NREC has funded nutrient removal projects that have fine-tuned the removal recommendation. You can find those recommendations in an article from Farmdoc here.
Key Questions to Ask:
- Has nutrient application over the last 3-5 years matched crop removal?
- Is your pH balanced to allow soils to offer the best supply?
- How are crop nutrient recommendations being made?
Recommendation:
1. Make a list of fields and fill in a column for the yield removed by corn and soybeans for the given year.
2. Calculate the total P205 removed (note these values reflect NREC)
a. Corn: Total Yield X 0.37 = Total Removal
b. Soybeans: Total Yield X 0.85 = Total Removal
c. Convert to the fertilizer source used
3. Calculate total K20 removed (note these values reflect NREC)
a. Corn: Total Yield X 0.24 = Total Removal
b. Soybeans: Total Yield X 1.17 = Total Removal
c. Convert to the fertilizer source used
4. Calculate total nutrient application during the desired span of years
5. Evaluating the difference
a. Total P205 Applied vs Removed = +/-
b. Total K20 Applied vs Removed = +/-
Crop Nutrient Balance Sheet:
Below is an example of a sheet that every producer should develop for every field that they manage. Over time account for P205 (DAP) or K20 (Potash) removed by grain and applied by replacement sources (manure or fertilizers). Consider a nutrient asset as supplying the field and a nutrient liability as the crop removal.
Edit 10/07/20: Previous version of article used values from the Illinois Agronomy handbook, which was updated by NREC research.
Todd Steinacher
Steinacher is an ISA CCA Soy Envoy alum and currently supports ISA on agronomic content as well as serving as an Illinois CCA board member. He was recently awarded the 2020 IL CCA of the Year & the 2021 International CCA of the Year. He has over 15 years agronomic experience, currently working with AgriGold and GROWMARK previously. Steinacher has an associate degree from Lincoln Land Community College, a B.S. in agronomy and business from Western Illinois University and a master’s degree in crop science from the University of Illinois at Urbana-Champaign. If you have any questions for him about this article, he can be reached at steinacher@ilsoy.org.
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