Illinois Worksheet for Expanded Crop Rotation
v. 9-7-04
Instructions
Ted Funk, Extension Specialist, Agricultural Engineering
General information. This is a worksheet written in Microsoft Excel. It was developed
as a “quick and dirty” tool to allow producers to perform a check of manure application
rates for a multi-year crop rotation, and to help keep track of nutrient credits that need to
be carried over from one year to the next. The spreadsheet was written by an engineer,
not by a programmer. Enhance it all you want; the author will not be offended. Just
protect the formulas and static data so the results are correct.
What the worksheet will do

Calculations of crop N, P, and K nutrient balances

Plan one field nutrient balance at a time. You can, of course, split a field
into subfields and plan one subfield at a time.

One manure analysis at a time. If you have a very large field and more
than one source of manure will be spread on it, you’ll have to run the
spreadsheet for two subfields.

Planning. You can track the N, P, and K balances for the field as a whole,
based on the fertilizer and manure program and the expected crop yield.

Reconciliation of plans with actual performance. The plan and the actual
implementation are never the same. The end-of-year reconciliation
worksheet allows you to show a comparison of what you planned for the
last crop season with what really happened: manure and fertilizer
applications, crop yields, etc.

Allow recordkeeping. Save a file for each field, and print out hard copy
for your plan records.
What the worksheet won’t do

Tell you directly what manure application rate to use. You must enter trial
application rates and see the results; in many cases you will want to go
back and make changes. However, some producers are comfortable with
their manure application rates already, and only want a tool to allow them
to document those practices.

Fertilizer and lime recommendations. Use the IL Agronomy Handbook
on-line, “Soil Plan” feature, for that.

Multiple fields at a time. For a more complicated software tool that will
do this, try the “Manure Management Planner” from Purdue or other
software.

Print summary reports for all your fields.

Multiple manure tests at a time.

Tell you when your data are no good, or your plan is out of compliance.
What cells to fill in
Yellow cells on the “Nutrient Needs” and “Nitrogen Credits” sheets.
Blue cells on the “End of Yr Reconciliation Sheet”. BE SURE TO CHECK THE DATA
IN THE BLUE CELLS each time you update the plan. Otherwise your end of year
reconciliation report will be wrong; it may be data from a run calculated for a different
field or a different year.
Worksheet protection. The cells that you do not have to fill in are protected so you will
not inadvertently overwrite the formulas and static data. If you unprotect the worksheet,
do so advisedly. Be sure you have an archive copy of the program.
Data and formulas.
 The average nutrient needs for crops are on the “nutrient needs” worksheet.
Instructions for adding a crop are posted above the list. If you make changes
and results appear strange in your worksheets, it may be due to improper
editing or sorting of the crops list.

Phosphorus (P) and potassium (K) are assumed to be conserved within the
system. Although some sources presume P and K in manure are not 100%
available the first year after application, this spreadsheet simplifies things by
using 100% availability. Most livestock producers won’t need to worry about
the first-year P and K availability anyway, and the 100% figure is
conservative in terms of environmental protection.

Keep in mind that “available N” doesn’t stick around from year to year, at
least in theory; regulations do not allow over-application of “available” N for
any one year. The program credits nitrogen mineralization if manure is spring
applied; and no nitrogen mineralization if manure is fall applied. Therefore, if
you apply manure anytime when soil temperatures are warm, you may as well
check “spring” application. That way the manure nitrogen mineralization will
be credited toward the proper crop year. Manure nitrogen credit for “organic
N” will be tracked from year to year.
Modifications possible. There’s no reason why you could not link all your fields into a
database and have the existing worksheets just do the calculations. It would take some
programming effort, and this project was meant to just do the “quick and dirty” version.
FAQ’s.
Q1. How will the producer or user of the Illinois Worksheet for 4-Year Crop Rotation
determine when the phosphorus applied in a multi-year application will have been used
in the crop rotation by the crops therefore allowing application to the site again?
A1. You can see on the “Reconciliation Summary” page the phosphorus carryover goes
way positive for years when over application occurs, and then drops back in the years
when less or no manure/fertilizer is added. Both the graph and the P2O5 carryover
number show the trend. The producer should see from the graph the expected carryover
following a multi-year application.
Q2. How will the user determine what application rate to use, (i.e. P based, N based or
no application of manure)?
A2. This worksheet does not prescribe directly an application rate. I’ve found that
calibration of equipment to “odd” rates is too problematic; it is more reasonable to input a
“nice even number” rate as a guess, then see what happens to the N, P, and K carryover
numbers and iterate the rates until rates are found that don’t result in carryover.
Q3. This relates to the above question, but is a separate issue. The P2O5 carryover can
show negative values when low amounts or no phosphorus is applied in previous years,
however the soil Bray P1 can be above that agronomically needed (i.e. Bray P1=300) due
to phosphorus applications or other causes that predate the years included in the
spreadsheet calculation. This worksheet could show what appears to be no carryover of
phosphorus when in fact a multiyear phosphorus application has occurred on a field with
a high Bray P1,the phosphorus has not been used by the crop, and there is carryover.
A3. That’s a good point, and the only way around that is for the producer to enter the
“carryover” of P2O5 in the Nutrients Carryover cell in “Year –3.” In that manner the
carryover will be figured in the same as with the other “visible” years. So to check
compliance, it’s the same task as with anybody else’s method: look at the records
previous to the permit. The spreadsheet goes back 5 years (current Year 2 back to Year
minus-3), the eventual term of the permit.
Q4. The nutrient balance worksheet shows the results of the calculation for the planned
N and P. The calculations should be included in the plan for the actually applied N and P
as well.
A4. The “End of Yr Reconciliation” and “Reconciliation Summary” pages do just that.
The blue cells are to be filled in by the producer (current Year 2 and following years)
with the same sorts of data entered in the “Nutrient Needs” and “Nitrogen Credits” pages.
The “End of Yr Reconciliation” page re-calculates from current Year 2 on, retaining the
values from Years minus-3 to Year 1. Then the “Reconciliation Summary” page brings
forward the resulting values for easier viewing, in table and graph form.