How are ERUs used in the Nitrogen model?
Overview:
Defining what an ERU stands for and explaining the impacts it has on the Nitrogen model.
Requirements:
- Field boundaries created.
- Crop Zones assigned.
- A management-zone region layer with a labeled group attribute on the field.
- (only required if check blocks are needed)
- An existing Encirca Decision Zones layer under the crop zone.
Answer:
Environmental Response Units (ERU) are a digital soil map and are intended to mitigate some of the spatial resolution issues with SSURGO. ERUs form the base soil layer used to create Decision Zones within Corteva and Granular Nitrogen. ERU 1.0 was introduced in Encirca for the 2013/2014 growing season. An updated version, ERU 1.1, was introduced in the fall of 2015 for the 2016 growing season. ERU 1.2.1 replaced ERU 1.1 in late 2016. It reclassified soil landscapes originally mapped with low resolution elevation data using higher-quality digital terrain data. The ERU soil map still uses the underlying SSURGO tabular datasets to provide soil attribute data for Corteva and Granular services. As with the SSURGO soil map, the ERU digital soil-mapping process can have variable results.
- Variability in the quality of the digital elevation data and differences in resolution compared to the scale of landscape variation in some areas reduces the effectiveness of the reclassification.
- The ERU process relies on the quality of the original survey to faithfully capture the relationship of soil types to the landscape position.
- The underlying soil parameters are derived from the SSURGO data. We have attempted to mitigate some of the missing data issues and issues around state and county boundaries, but some idiosyncrasies still exist.
- The local knowledge of the Granular certified services agent is extremely helpful in improving the quality of soil data input into the Granular Nitrogen service.
- Review by the University of Missouri and USDA - ARS showed that the use of ERUs produces a better result than SSURGO in the majority of situations.
Related articles:
What is SSURGO?
How does the quality of ERU compare to SSURGO?
