What impact does a single rainfall have on the Granular Crop Model?
Requirements:
- Corteva Connection Establish (If wanting to push/pull zones)
- Roles and Permissions set
- Invoice Granular Agronomy through Connex
- Fields are in Insights
- Crops Assigned in Activities
- Decision Zones Created or Synced from Corteva
- Field Details Set
- Add New Nitrogen or Planting Events
Answer:
There are many factors that impact the Granular Crop Model. Precipitation is critical to monitor over the course of a growing season, not just an individual rain event. Individual rain events reported by a station or a grid can over- or under-report a single event, but generally average out over the course of a season.
A recent study measured the effect of precipitation on nitrogen in the model. In the study, 37,800 simulations were performed to add extra rain events in each of the critical months (April - July) where water has an impact on crop development and nitrogen loss before silking. A range of soil types from sands to loams to mucks were included as well as a wide range of weather years (20) and three typical nitrogen plans.
The table below shows the effect of an additional 0.5” or 1” precipitation added to any existing rainfall on the first day of each of these months. The result (Potential Soil N difference) is the approximate difference in total soil N available at VT/R1 between the original rainfall and the adjusted event. Potential Soil N loss varies within the range below based on soil type, current moisture levels, and depth at which N is measured. Losses are generally larger with fall applications on highly permeable, light-textured soils, wetter years, and rain events that occur closer to silking. In dry years, additional rainfall results in an increase in nitrogen available at silking because of improved conditions for mineralization.
|
Potential change in soil N at silking based on past 20 years of weather (varies by soil type, soil moisture level, nitrogen application timing and source, previous weather)* |
||
| Amount |
0.5 inch precipitation |
1.0 inch precipitation |
|
Date of precipitation event |
Change in N (lbs./acre) Min / Average / Max |
Change in N (lbs./acre) Min / Average / Max |
|
April 1 |
0 / -1 / -1 |
-1 / -1 / -3 |
|
May 1 |
0 / -2 / -11 |
0 / -3 / -15 |
|
June 1 |
+1 / -3 / -17 |
+1 / -4 / -34 |
|
July 1 |
+6 / -3 / -21 |
+6 / -6 / -44 |
*Nitrogen plans - Fall NH3 with inhibitor + spring UAN weed and feed; All Preplant; Preplant weed and feed followed by early June sidedress.
Soil textures include loamy sand, loam, silt loam, clay loam, silty clay, and muck. Loamy sand modeled at 4 feet, all others at 2 feet.
Weather years 1998-2017.
Related Articles:
How does Corteva Weather Pillar source weather data?
How does the Granular Crop Model track soil moisture?
What is the estimated runoff from rainfall events?
How does irrigation affect the Granular Crop Model?
