Every VRA map has a lifecycle - generated → reviewed → approved → exported → applied → verified. Each step emits an event into Activity & Alerts and, once applied, becomes an eligible source event for Verification.
Understanding Variable-Rate Application
Variable-Rate Application (VRA) divides a field into management zones - groups of pixels with similar index values that represent areas of comparable agronomic status. Each zone receives a different application rate tailored to its needs. A high-biomass zone might receive a maintenance nitrogen rate, while a consistently low-performing zone gets a corrective higher rate to close the yield gap. Semai automates zone delineation using the vegetation index of your choice, then lets you assign and fine-tune rates per zone before exporting a file your equipment can execute directly.What actually validates today
Read this before the walkthrough below. Zoning works for every crop. Rates are the constrained part, and most of them do not validate against a published band, because for most crop-product pairs no published band exists.
Eleven other crop-product rows are
decision_required and will stay that way until an agronomist fills them from primary documents. See the Risk Model for the table and the open sourcing questions.
Management zones derived from multi-date imagery composites are more reliable than zones from a single image. Semai automatically uses a seasonal composite when more than three imagery dates are available for the selected season.
Creating a VRA Map
1
Open the VRA tab
Navigate to Fields, select your field, and click the VRA tab. Any previously created VRA maps for this field are listed here.
2
Start a new VRA map
Click New VRA Map. A setup panel opens on the right side of the screen. If you arrived here from a scout completion or risk card, the base index and target hazard are pre-filled.
3
Choose your base index
Select the vegetation index that best matches your application goal:
- NDVI — use for variable seeding rates and general biomass-based zoning
- NDRE — use for variable nitrogen application; more sensitive to chlorophyll at high biomass
- NDWI — use for variable irrigation scheduling or fungicide timing by canopy water status
4
Set the number of management zones
Choose between 2 and 5 management zones. For most fields, 3 zones (low, medium, high) provide the right balance of spatial detail and practical manageability. The platform auto-clusters pixels using k-means and displays the resulting zone map immediately.
5
Review and adjust rates per zone
The system assigns default relative rates scaled to your base application rate. Edit the rate for each zone to match your agronomic targets. The shape of the table looks like this:
6
Submit for review or export
A VRA map moves through a review lifecycle before it is applied. Click Submit for Review to hand it to an approver, or Export directly if you have export permission. See VRA lifecycle below.
7
Export in your equipment's format
Once approved, click Export, choose your equipment format (see table below), and download the file. Load the file onto your display or precision ag platform before heading to the field.
VRA lifecycle
Every VRA map moves through a defined lifecycle. Each step emits an event into Activity & Alerts so operators, agronomists, and (later) verifiers can trace the full history.Roles
Amended 11 August 2026. An earlier version of this table named Operator and Read-only, neither of which is one of the eight functional roles in the role model. This page predates that model and was never reconciled with it. The permissions were kept; only the role names changed.
Defaults above; role permissions are configurable at the org level.
Where the old names went, and why.
Operator → distributed, not renamed. Its three permissions do not belong to one actor. Uploading as-applied data is scout work — the role’s documented function is ground-truth work: visits, photos, observations, and a record of what actually went on the ground is exactly that. Generating belongs to agronomist and above. Exporting is gated on approval and available to anyone in scope who may generate.
Read-only → viewer, and its Review tick is removed. Review is defined in the lifecycle as “Map opened, zones and rates confirmed. Comments attached.” Attaching a comment is a write. A role that cannot write cannot review, and the old row was internally contradictory. A viewer reads every map on this screen and records nothing against it.
No ninth functional role was added. The eight are closed by design, and this page inventing a role is the case that rule exists to prevent. A role governs permission, not identity — the audit already records actor on every write, so the person who exported or applied a map is named regardless of what their role is called.
Approval is a second person
The approver may not be the author. A prescription that one person writes and the same person approves has had a single reader, and it puts fertiliser on the ground. This mirrors the acknowledgement rule on findings, and it binds harder here: a finding is a claim, a prescription is an act. It also matters more since attribution became a route to a permitted rate — a rate resting on one person’s judgement, approved by that same person, is a single unchecked point of decision on a physical operation. The fallback, so a small estate is not deadlocked: where no other entitled person has been active on the estate for 24 hours, approval falls toestate_manager, and the record shows it took the fallback route. Where the author is the estate_manager, approval falls to an in-scope approver. If neither exists, the prescription waits — it is not self-approved.
map.approved records both names: who wrote it and who approved it.
Export Formats
Variable-rate application may be subject to local regulations around maximum nutrient application rates, buffer zones near waterways, and record-keeping requirements. Check with your local agricultural authority or agronomist before executing a prescription map, particularly for nitrogen and pesticide applications.
Reviewing Results After Application
Close the loop by uploading your as-applied data after the application pass is complete. Most precision ag displays export an as-applied shapefile or CSV that records actual rates applied at each GPS point. To upload as-applied data:- Go to the field’s VRA tab and open the completed map.
- Click Upload As-Applied Data and select your file.
- Semai overlays the target prescription and the as-applied data side by side, highlighting areas where applied rates deviated from the prescription by more than 10%.
map.applied into Activity & Alerts with the deviation summary, and starts the cross-check against the next satellite pass. Once the cross-check passes, the entry becomes eligible for Verification.
Use the deviation comparison to identify equipment calibration issues, coverage gaps, or overlaps, and carry the findings into your next application planning session.
Guardrails
This module follows the shared guardrails template. The agent and every non-agent write path must respect these rules.Related
- Field Scouting - a scout completion often triggers a new VRA map, especially for confirmed disease or nutrient hazards.
- Activity & Alerts - every lifecycle event lands in the feed with severity and countdown.
- Activity Log - VRA lifecycle rendered as Gantt bars across the season.
- Risk Model -
map.appliedevents reset severity on the targeted rule card. - Verification - turn applied VRA maps into satellite-stamped proof for subsidy, takaful, and NADMA claims.
- Fields Workspace - the workspace where a VRA map is typically initiated from an anomaly or rule-card finding.