By Steve Culman
NutrientStar, an independent evaluator of nutrient management tools, has just released results testing the performance of two web-based tools that provide customized corn nitrogen fertilizer rates: Adapt-N and Climate FieldView. Both tools are available for farmers in Ohio to use for a fee.
NutrientStar conducted 61 trials over 3 years evaluating Adapt-N and 21 trials over 2 years evaluating FieldView in Ohio. A summary of findings is presented below.
Summary of Performance of Adapt-N and FieldView Compared to Farmer Normal Practices.
Tool | Year | Trials | Change in Yield (bu/A) | Range of Change in Yield (bu/A) | Average return to N ($/A) |
Adapt-N | 2017 | 11 | -41 | -91 - -2 | -131 |
| 2016 | 17 | -9 | -31 - 3 | -6 |
| 2015 | 33 | -8 | -42 - 33 | -17 |
FieldView | 2017 | 11 | -8 | -19 - 3 | -24 |
| 2016 | 10 | -9 | -25 - 0 | -11 |
Compared to ‘farmer normal practice’ using the tools produced a range of yield differences across trials and years in Ohio. Some trials yielded more grain using the tools (positive values) and some yielded less grain (negative values). When all trials within a year were averaged, both tools resulted in lower yields compared to farmer normal practices (8 – 41 bushels/acre less). Depending on the year, farmers lost on average between $6 – $131/ acre on their return to N fertilizer.
The results varied by state, with some states benefiting from the tools and other states not benefiting from the use of the tools. Unfortunately, these tools have not performed well in Ohio to date.
An alternative approach to deciding corn N fertilizer rates is to use the economic model that Ohio State University Extension endorses. This simple calculator is based on maximizing farmer profitability. It uses 3 inputs to determine at what point will additional N fertilizer not pay for itself with more yield. This free, publicly-available tool was recently updated with extensive on-farm trials in Ohio and can be found here:
http://go.osu.edu/corn-n-rate