Variable Rate Field Configuration
Adapt-N's full-field variable rate prescription feature provides powerful nitrogen recommendations that are weather-adjusted, site-specific, and account for substantial sub-field variation. Just like with any other Adapt-N recommendation, users can control various inputs and can analyze the makeup of the recommendation before deciding exactly what to apply in the field. Service Provider, Enterprise, and Precision Trust licenses may request access to the Variable Rate features by contacting email@example.com.
Creating a Field for Variable Rate Purposes
Variable rate prescriptions may be generated by importing a Shapefile or by syncing the field boundaries to a data source, such as the agX Platform (see instructions here). Fields drawn by hand within Adapt-N are not eligible for variable rate prescriptions due to the precision needed to appropriately utilize the recommendation. Shapefile imports should be conducted for a single field, although multiple polygons within that field are supported. Full instructions on importing field boundaries using Shapefiles are located here.
Once a field boundary has been imported into Adapt-N, select the "VRT Grid" zone creation method:
When looking at the Fields & Zones view, VRT Fields have a graph icon next to their name, whereas point-based fields have an arrow next to their name (to expose manually created zones):
Configuring a Variable Rate Field
Click "Configure Field" on the Fields & Zones view, or click the "Configure Field" item in the Field menu, to enter the VRT field configuration interface:
The Variable Rate Field Configuration Interface is then displayed. Similar to point-based fields, users provide information specific to the field and farm management practice. The configuration for each layer of data is accessed by clicking on the layer name. The following layers may be configured in variable rate fashion by importing a Shapefile or by Syncing to a Data Source:
- Soil Type
- Soil Organic Matter
- Expected Harvest Population
- Expected Yield
- Nitrogen Applications
Other layers of data, including crop rotation, tillage method, and manure and irrigation applications, are configured in a flat-rate fashion for the entire field. These layers may become variable in the future. If you are syncing a field to the agX Platform, please reference this article instead, as the remainder of this article assumes the field was imported using a Shapefile.
Click a layer's name to expose its data import options. For example, the Soil Organic Matter layer accepts a Shapefile or a Constant Value. Click the data import type (e.g. Shapefile) to expose additional controls, including a way to locate the Shapefile on your computer, input fields for additional required data, and in some cases optional input fields for Default values.
- Shapefiles must be submitted in the form of a Zipfile, containing the individual Shapefile components (.shp, .shx, .dbf, .prj).
- For soil type, slope, expected harvest population, and nitrogen applications, the data within the Shapefile should be polygon-based. For soil organic matter, either polygon or point-based data is accepted.
- You may submit multiple columns within a single Shapefile, which you would select within each layer, or you may submit separate Shapefiles each with one column of data. If multiple columns of data exist, you will be prompted to identify the proper column of data for the layer being configured.
Here is a view of an example Shapefile, containing columns as follows:
- AREASYMBOL: represents the FIPS code required by the Soil Type Import (FIPS is a 2-digit state and 3-digit county code).
- MUSYM: represents the MapUnit Symbol required by the Soil Type Import. This corresponds to the SSURGO soil database provided by NRCS.
- Yield: the expected yield value for each polygon within the field, represented in bu/ac.
- SOM: represents the soil organic matter % for each polygon within the field.
- Population: represents the expected harvest population for each polygon within the field.
- PreplantN: represents pounds per acre of nitrogen already applied to the field.
This sample Shapefile is available for download at the bottom of this page.
When submitting the Shapefile to Adapt-N, a dialog box will prompt you to select the appropriate column in your shapefile for the data layer you are submitting:
Any column name is acceptable, as long as it does not start with a number. When the Shapefile has been processed, a confirmation will indicate the area of the field covered; in cases when the Shapefile does not cover the entire field, the optional Default Value will be used.
All layers are required except for Nitrogen Applications, Manure Applications, and Irrigation Applications. You can partially complete a field configuration and return to it later, as each layer is saved individually once submitted.
Running a Variable Rate Recommendation
Once the required layers have been configured, Activate the field (either from the top of the VRT configuration interface or from the Fields & Zones view). To initiate the variable rate recommendation, click Run Active Zones from the Field menu. This launches a background process to run the necessary simulations for that field.
You may continue working elsewhere within Adapt-N, or you may visit the Field Recommendation page to monitor its progress. A notification badge will be displayed in the navigation bar, above your name, when the recommendation is complete (it may take several minutes). Alternatively, you may click on the icon above your name to check on the status of processing and completed recommendations. Click on the field name to access the recommendation:
Or, visit Fields & Zones and click "Field Rec" on the Field menu to access the recommendation page:
When loading a recommendation that is still processing, partial results will be displayed, with the option to reload the page.
Viewing a Variable Rate Field Recommendation
Once configured and activated, the Adapt-N Variable Rate Recommendation runs automatically on a daily basis, taking advantage of updated weather and any changes entered by the user. Additional features of the recommendation include:
- Summary of Field Rec: includes the minimum, average, maximum, and total pounds of N recommended
- Date selector: select from any date back through 2010, in order to re-run the prescription using the actual weather from the start of the selected season to the date specified (all management dates are automatically adjusted for the simulation)
- Interactive map: click on any of the grid cells to see the specific recommendation for that 60' x 60' cell; click view details for full scientific simulation results, including PDF reports and interactive graphs for that cell
- Interactive graph: hover your mouse over bars in histogram or the values in the legend to highlight the grid cells on the map applicable to those recommendation ranges
- Summary of VRT inputs: shows the minimum, average, and maximum values for the variable rate inputs; if applicable, a summary of nitrogen, manure, and irrigation applications is also displayed
- Export Recommendation: choose export format, products, and make rate modifications. View this article for details.
Between growing seasons, Adapt-N field configurations need to be migrated to the next season. This information can be migrated manually starting on September 1st. If the user does not migrate fields manually, all fields will be migrated automatically on January 1st.
What this means:
- Planting date will be set to the same date in the coming season as was set last season, which should be updated when the real planting date is known
- Harvest population values will be carried forward
- Yield target values will be carried forward
- Crop rotation will be carried forward
- Soil information will be carried forward, including organic matter and pH values
- Manure applications which are valid for the current growing season will be carried forward. For the 2023 growing season, this includes manure applications from 2021-01-01 forward (see here for details)
The following information will not be carried forward:
- Nitrogen applications
- Irrigation applications
- Observation values for crop emergence and soil nitrate levels
- Cover crop information
Any information that was migrated to the next season can then be updated to reflect management practices for the next season.
To migrate a field to the next growing season, simply click the Migrate to ____ Season button under the desired field in the Fields and Zones page.
Once this action is complete, users will be able to begin configuring that field for the following season. The previous season's configurations can be viewed by returning to the field configuration screen and selecting the previous season from the dropdown.
Using Soil Survey Data for Zone-Based and Grid-Based Fields
When the Sync with a Source option is selected for Soil Type or Slope layers on a Grid-Based field, Adapt-N's internal Soil Survey database is used to configure the field. Specifically, each grid cell in the field will be automatically set with the appropriate values:
- Soil Texture will be specified based on Adapt-N soil regions and databases
- Drainage classification will be set
- Adapt-N's default rooting depth will be set
- The slope % will be set
In cases when the Soil Survey database lacks sufficient information for a part of a field, only then will the user-provided Default Values be used.
In all cases, the system will inform the user the percent of the field which was set automatically vs. by user-provided defaults.
Users always have the option to upload a Shapefile to set these values, instead of using Adapt-N's databases.
Soil Organic Matter
Soil Organic Matter
Adapt-N recommends using a soil organic matter test that was conducted in the last 3 years. Values can be entered as a flat rate for the whole field, individually by zone, or can be submitted spatially using grid- or zone-sampled shapefiles and integrations. In all cases, the % organic matter and sample depth are required.
The purpose of providing a previous crop is to provide the model with information about remaining crop residues and their influence on N availability (immobilization in high carbon residue, or additional N in legume residue). We are working on incorporating cover crops and other crops into the Adapt-N rotation options. In the meantime, if the crop planted in the previous year is not listed as an option under Previous Crop, a crop with a similar growth pattern (planting density, crop residue) should be selected. Here are a few suggestions about how to generate the most accurate results:
- Small grains, straw harvested: Substitute silage corn for small grains. The reason for this is that, like silage, small grains after straw harvest leave a minimal amount of surface residue, so that little immobilization of nitrogen occurs. The amount of root residue left by densely planted grains is likely similar to more broadly spaced, but larger, corn root residue.
- Small grains, straw left on surface: When following small grains where straw was not harvested (if residue is still fairly thick by corn planting time) use “grain corn” as the previous crop, so that some immobilization of N in residue will be accounted for, although imperfectly.
- Vegetable crops/potatoes: Substitute soybean for vegetable crops/potatoes, but be sure to add the soybean N credit listed on your results page to your Adapt-N recommendation (15 lbs or 25 lbs, depending on location and soil type) for non-legume vegetable crops. Like soybeans, most vegetable crops leave minimal residue, but most do not fix nitrogen.
- Cover Crops: Currently your best option is to use a cover crop credit (if applicable) as suggested by your local extension system. We plan to have a beta-module for cover crops available for testing for the 2016 season.
Expected Harvest Population
Adapt-N asks for an approximate harvest population to create your nitrogen recommendation. Plant harvest population options are in increments of 1,000 ranging from 15,000 - 40,000 plants/acre.
When Sync with a Source is selected, Adapt-N will display all available datasets containing planting rate information, including some basic statistics about those planting records. The default value is optional, and will only be used in cases when the selected agX data does not cover the entire field. This includes:
- Crop Establishment and Input (CEI) Applications
- Crop Establishment and Input (CEI) Recommendations
Adapt-N automatically calculates 90% of the planting rate for use as Expected Harvest Population when importing from SST only. When using the shapefile import and entering a constant value, Adapt-N will not calculate 90% of the planting rate and users must do that manually within the file.
Adapt-N is used as a predictive tool in the early growing season, and the expected yield should therefore be based on an achievable yield, not an average yield, based on the real-world field-specific situation. If seasonal growing conditions are good, we recommend to use the highest yield of the past five years. When the growing season around sidedress time already shows suboptimal conditions (late planting, water stress, pest damage, etc.) adjust the yields downward as appropriate.
A post-season evaluation of Adapt-N should not be based on the achieved final yield of that growing season, as this may have been impacted by late-season processes like drought, weed competition, hail, or pest pressure that are unrelated to crop N uptake and cannot be predicted at sidedress time. This would not be representative of the use of Adapt-N in a real-world scenario, where an N rate recommendation must be made in spring or early summer.
Adapt-N models the impact of different tillage methods on nitrogen availability. It simulates decomposition of incorporated vs. surface residues, and adjusts temperature and moisture conditions.
There are nine Tillage methods available for use in Adapt-N:
- Conservation tillage: select the approximate % of the previous crop’s residue remaining on the surface after all tillage passes. Conservation tillage leaves at least 25% of the previous crop’s residue on the surface.
- No-Till: no additional input values are needed. This is modeled equivalently to Conservation Tillage with 100% residue.
- Spring Tillage (only): enter the approximate date of tillage and the approximate depth of tillage.
- Fall Tillage (only): no additional input values are needed.
- Fall and Spring Tillage: No additional input values are needed.
- Strip-Till/Zone-Till (Spring): no additional input values are needed. Adapt-N assumes a residue percentage of 75%.
- Strip-Till/Zone-Till (Fall): no additional input values are needed. Adapt-N assumes a residue percentage of 75%.
- Ridge-Till (Spring): No additional input values are needed. Adapt-N assumes a residue percentage of 50%.
- Vertical Tillage: No additional input vales are needed. Adapt-N assumes a residue percentage of 50%.
Important note: If multiple methods of tillage are used, select the option that most closely reflects the effects on crop residue incorporation.
When specifying Tillage % Residue, only a general estimate of the % residue remaining from the previous year’s crop is needed (the options in Adapt-N are 25, 50, 75, or 100%). For guidance on estimating this value, you can use the percent surface residue values detailed in the following Purdue University fact sheet: https://www.extension.purdue.
So that Adapt-N can account for Nitrogen already added to a field (and how much of that N was taken up by the crop vs. lost), it's important to accurately enter each N application into the system.
In addition to entering the information while configuring individual fields, nitrogen applications can be entered across multiple fields by clicking the "Applications" icon from the left navigation bar, or selecting "Nitrogen" using a zone's view menu option.
Enter each Nitrogen application, specifying:
- The type of application (Pre-plant, Starter, Pre-Emergence, or Sidedress)
- The date of the application (if Starter, date is not required as the planting date is automatically used)
- The type of fertilizer
- The amount applied and the units for that application (users have the ability to select lbs-N/ac OR gal product/ac if it's a liquid product and lb product/ac if it's a dry product; Adapt-N will convert units of product to units of N, and vice versa, automatically)
- The placement of the application (surface through 10" depth)
- Enhanced Efficiency Products (EEP) used, if any
Adapt-N accepts 1 Nitrogen Application of the type "Starter", to represent N applied at planting. If you have applied more than one type of Nitrogen at planting, you can represent the additional starter applications by adding them as Pre-Emergence applications, specifying the planting date as the Application Date. Adapt-N will treat this in the same way as Starter.
Enhanced Efficiency Products (Stabilizers)
Enhanced Efficiency Products (EEP) options include urease inhibitors, nitrification inhibitors, combined inhibitors, and poly-coated urea. Impacts on N recommendations depend on the effectiveness of the materials, seasonal conditions, management practices, and soil characteristics (esp. organic matter content).
Adapt-N currently incorporates the specifics of the following active ingredients/trade names into its nitrogen recommendations:
Active Ingredient Trade Name NBPT Agrotain-Ultra/Dry NBPT+DCD Agrotain-Plus Nitrapyrin N-Serve / Instinct MIC NutriSphere-N Ammonium/calcium thiosulfates Thio-Sul / CAT Poly-coated urea ESN NBPT+DCD impregnated Urea SuperU
Adapt-N's inclusion of, exclusion of, or reference to any trade name is not an endorsement of that product or its manufacturer. Our modeling of these products is based on research associated with the active ingredients in these products.
Additional notes on utilizing EEPs within Adapt-N:
- The use of an EEP must be associated with an appropriate Fertilizer Type in the course of entering a fertilizer application into Adapt-N.
- When using ESN or SuperU, also select Urea as the Fertilizer Type, as it includes both the fertilizer and control mechanism.
- Adapt-N is not calibrated for the use of EEPs in conjunction with high rates of manure application at this time. Users are advised against modeling manure applications with EEPs, the effectiveness of this practice is not well understood.
Nitrogen applications can also be submitted by uploading a shapefile. With a shapefile upload, users will have to also select which shapefile field correctly corresponds to the units that was selected previously (lbs or gal of product or lbs of N).
Adapt N will then convert lbs or gallons of product to lbs of N (and vice versa) automatically as shown below.
To modify existing Nitrogen applications or view them on the map, click View Past Applications
You can then click Remove, Edit, or View on Map
Applying an Adapt-N Rec Export to a Field
Once an Adapt-N recommendation has been exported as a Shapefile* via the Field Recommendation Export page, a new option becomes available on the Field Configuration screen's Nitrogen Applications layer: "Apply Adapt-N export"
"Apply an Adapt-N export" enables the selection of any past Shapefile* export from this field to be used as a new Nitrogen Application on the field. Fill out the form for application date, type, placement, and Enhanced Efficiency Product, then click to select the desired Adapt-N export file.
If multiple exports exist for the field, preview the information about each selected recommendation to choose the desired export.
The system will automatically perform the necessary product rate conversions and apply the exported recommendation back to the field at the appropriate applications rates across the field. If a custom fertilizer was used during the export, you may be prompted to select the most similar standard fertilizer type during the import. This selection is only necessary for loss and uptake modeling purposes, not for product rate conversion purposes (even with custom fertilizers, the actual N-P-K makeup of the product is appropriately converted to pounds of nitrogen).
A common use for this feature is as follows:
- configure a field in Adapt-N and use it to generate an early sidedress recommendation
- apply that sidedress recommendation in the field
- use this feature to apply that recommendation to the field in Adapt-N on the date it was actually applied in the field
- Adapt-N continues monitoring the field on a daily basis; use N-Alerts or the Dashboards to see if additional N applications may be needed later in the season
* = any export that results in a shapefile being produced is available for use via this feature. This includes Adapt-N's standard shapefile export as well as exports to John Deere Operations Center.
So that Adapt-N can account for additional sources of N (and how much of that N was taken up by the crop vs. lost), it's important to accurately enter each manure application into the system. Historical manure applications can be entered for up to two calendar years in the past. For example, valid manure applications for the 2023 growing season would be any applications made on or after January 1, 2021.
In addition to entering the information while configuring individual fields, manure applications can be entered across multiple fields by clicking the "Applications" icon from the left navigation bar, or selecting "Manure" using a zone's view menu option.
Enter each Manure application, specifying:
- Ammonium N and Organic N
- The date of the application
- Incorporation Method (Incorporated/Injected immediately, within 2 days, within 5 days, or left on surface)
- The rate of application (tons/acre or gallons/acre)
- Percent solids
- Manure Type
Manure applications can also be submitted by uploading a shapefile.
To delete existing manure applications or view them on the map, click View Past Applications
You can then click view on map, remove, or edit.
So that Adapt-N can accurately model the movement of nitrogen in the soil profile, it's important to enter all irrigation events.
In addition to entering the information while configuring individual fields, irrigation applications can be entered across multiple fields by clicking the "Applications" icon from the left navigation bar, or selecting "Irrigation" using a zone's view menu option.
Enter each irrigation application, specifying:
- Date of application
- Inches applied
Irrigation applications can also be submitted by uploading a shapefile.
To delete or edit existing irrigation applications or view them on the map, click View Past Applications
You can then click view on map, remove, or edit.
For more information on more accurately modeling different types of irrigation practices consult our Additional Irrigation Information article.
Additional Irrigation Information
For furrow, sprinkler, or drip irrigation, it's important to remember that water can be lost on the way to the pump, or after it has been pumped onto the field. The water can be lost to evaporation, surface runoff, or percolation below the rootzone of your crop.
Determining how much effective irrigation your crop will receive requires making an estimate of the efficiency factor for your irrigation system. The following suggestions are for estimating efficiency between your pump and the field. Start with the range of factors in the table that correspond to your irrigation method. Then consider your local conditions and choose a value in that range. If the weather is especially warm or windy, your efficiency will be lower. If your soil has a loamy texture water infiltrates more slowly and evenly, so your efficiency will be higher than on a sandier soil.
Field application efficiency
Furrow with tailwater reuse
65 - 85%
The application efficiency along with Rate (gal/min), Area (acre), and Time (hours) can be entered into our Irrigation Calculator (click here to download it in Excel). The calculator will assist you in determining the correct precipitation equivalent to input into Adapt-N as an irrigation event.
Adapt-N models the contribution of terminated cover crops to available nitrogen. This contribution depends on the following inputs:
Cover Crop Type: select grass, legume, or a mix of the two. Mixes are approximated to mostly grass, mostly legume, or an even mix.
Cover Crop Stand: select the best description for cover crop stand at the time of termination. Stand refers to the density of plants, which results from original planting density, crop establishment, and/or winter kill. Sparse stand implies lower plant density with large or numerous thin or bare spots. Medium stand implies medium density, moderate winter kill or thin patches or bare spots. Dense stand implies good establishment with little winter kill.
Cover Crop Stage: the approximate growth stage at which the cover crop was terminated. For mixes, including mixes that are mostly legume, use the growth stage of the grass component.
Cover Crop Incorporation (after termination): select whether the cover crop was left on the surface, partially incorporated, or fully incorporated.
Termination Date: enter the date the cover crop was terminated (surface killed or incorporated). This date must be before any spring tillage event.
The Rooting Depth parameter for a zone is used to determine whether nitrogen that has moved within the soil profile during the season is still within reach of the crop's roots, or whether it is effectively lost. Adapt-N has developed a database of realistic rooting depth defaults for each combination of soil texture and drainage classification in each county. However, since management practices and field/weather conditions can have a significant impact on rooting depths over time, we recommend users evaluate actual rooting depth in their fields and make adjustments accordingly. Consider taking penetrometer measurements to account for compaction and rootzone limitations. Consider weather influences that may impact rooting depth (e.g., very high rainfall tends to reduce rooting depth).
Evaluating Rooting Depth in a Field
The easiest time to evaluate rooting depth of a fully grown crop is after the season ends. In a few representative locations, dig deep enough so you can easily pull out the root mass without breaking off a lot of roots, or dig a small trench and view them from the side. The rooting depth should be assessed based on the vertical proliferation of a majority of roots, not an incidental root that may have gone deeper than most. We do not recommend relying on rooting depth values from soil survey databases, which tend to be overestimated. The actual rooting depth discovered should then be applied to Adapt-N for the following seasons. In the case of a very wet early growing season, it may be worthwhile to assess whether rooting depths are reduced, especially in fine-textured soils and when drainage is imperfect, and update Adapt-n accordingly.
If you have not had an opportunity to evaluation rooting depth in advance of the season, it can still be evaluated during the season. We recommend digging up roots no earlier than V7.
Modifying Rooting Depth Values in Adapt-N
To adjust rooting depth of an individual zone, access the zone's land information and use the Rooting Depth drop-down to view both the default value and to modify the selected value:
Zone- and grid-based fields can have their Rooting Depth values modified either as a flat value, or spatially, via the Configure Field interface. If a Shapefile is provided, values should be specified in inches. Else, the "Enter a Constant Value" option enables the entire field to be made more shallow, deeper, or set to a specific value.
When the Rooting Depth panel is open, the top of the Configure Field interface displays the current values across the field.
Applications of nitrogen, manure, and irrigation may be applied to parts or all of a VRT Grid field, and either at a constant or a variable rate. To remove an existing VRT Grid field's applications:
- Return to (or reload) the Field Configuration interface
- Open the layer of application type you wish to modify (e.g. Nitrogen Applications)
- Then click the "View Past Applications" link
- You will then be presented with a list of existing applications, with an option to Remove them