27 Jan 2009

Rate Reduction Calculator

Estimating Yield Loss from Nutrient Rate Reductions

A common question asked in unfavorable economic times is, “How much yield loss can I expect if I cut my nutrient rates?”

The resources provided here offer one approach to coming up with such an estimate.

RateReductionCalculationMethods.pdfThis paper outlines the scope of the problem, the assumptions made in the calculation, a description of the calculation with step-by-step examples, and references in tables that can be used to estimate the yield without nutrient applied.
RateReductionCalculator.xlsThis spreadsheet automates the calculations described in the document. It calculates yield loss based on the following user-inputs:

1) recommended rate of nutrient

2) amount to reduce the recommended rate

3) cost of a unit of nutrient

4) price of a unit of harvested crop

5) expected yield

6) yield with no nutrient applied (optional – but will improve estimates if used correctly)

When using the spreadsheet, please take note of the assumptions being made. Using improper assumptions can adversely affect the quality of the yield loss estimate.