Nitrogen Management in Poorly Drained Soils
When working with soils identified as ‘Very Poorly Drained’, pay special attention to the modeled recommendation. To simulate actual conditions, The Nitrogen model stresses the crop when there is a high amount of soil water and low concentration of nitrogen. If there is not enough nitrogen for the crop to get started, our crop model will simulate some growth, but usually will not complete the growth cycle, and the nitrogen recommendation will be 0 for the given zone(s). This is not the model failing but rather a symptom of edge cases around the model use.
For the 2019 season, you have a few options for insuring the crop is not dying on your impacted zones; both insure that the zones are not starting the season at 0 to low pounds of N:
- Increasing the initial N
- Setting the field to be Tile Drained. In the model, this adjustment increases the internal drainage and therefore can improve successful initial simulation.
- Adding a ‘crutch recommendation’ of Nitrogen close to variable rate application date (within 10 days). This application will give the crop enough nitrogen to create a recommendation. Once the recommendation is successful, you can adjust the recommendation and delete the ‘crutch’ application.
To check drainage status for a given crop zone or soil type, navigate to Field Planner for a given field and select Layers, Decisions Zones, and the label dropdown to Enclass Soils. From Field 360 Studio, select on the Encirca Decision Zone. From the menu bar, select “Layers” and then Layer Editor. From here the EnClass attribute column can be viewed. Note: Not all soils labeled as “Poorly Drained” may experience this issue, but those soils that have issues will be labeled “Poorly Drained”.
Here are reported soils experiencing this issue:
- Bellcreek silty clay loam
- Westland clay loam
The Nitrogen Product and Science teams have investigated an alternative approach when doing modeling, and would like to change the model optimization structure to limit the effects of low N on the field timing out the model. However, this would be a fundamental change, and the team is not comfortable risking the stability of Nitrogen for this update. Also, we will be looking into the classification of ‘Very Poorly Drained’ soils to insure this categorization is correct. This validation of categorization be an ongoing as it involves the Granular and Corteva Data Science team. Both of these updates will be tackled in future iterations of the model.