Are there any crop nutrition tools that handle variable-rate compatibility for fertilizer recommendations?

Yes. A number of crop nutrition tools support variable-rate fertilizer recommendations or at least output recommendations in a format that can be used for VRT application maps.

Common capabilities to look for:

• Zone-based recommendations from soil tests, yield maps, imagery, or EC layers
• Prescription map export for monitors/controllers
• Compatibility with variable-rate spreaders, sprayers, or planters
• Support for grid sampling or management zones
• Integration with GIS / precision ag platforms

Examples of tools/platforms that often support this kind of workflow:

• Climate FieldView
• John Deere Operations Center / agronomic partners
• Granular Insights
• AgStudio / SST Summit
• Raven Slingshot / VRA tools
• Trimble Ag Software / precision ag modules
• Ag Leader SMS
• Pioneer Field360 / Encirca-style services depending on region and version
• CropX, Topcon, Sentera, and other decision-support platforms that can generate zone-specific recommendations

A few notes:

• Some tools are mainly recommendation engines and rely on another system to turn those into a machine-readable application map.
• Others are fully VRT-compatible, meaning they can export shapefiles, ISOXML, prescription files, or controller-specific formats.
• Compatibility depends on your equipment brand and file format support.

If you want, I can help you narrow this down by:

1. Crop type
2. Country/region
3. Equipment brand/controller
4. Whether you want recommendations only or recommendations + prescription map export