A yield monitor measures how much grain your combine is harvesting — field zone by field zone — so you can see exactly where your crop performed and where it didn't.
See Green Growth KitsEvery combine moves through a field at varying speeds, cutting a swath of crop. Without a yield monitor, all you know at the end of the day is the total tonnage on the trailer tickets. You don't know whether the corner near the ditch yielded 8 t/ha or 4 t/ha — and you have no record of whether that pattern repeated last year.
A yield monitor changes that. It sits on the clean grain elevator — the conveyor that carries harvested grain up toward the grain tank — and measures how much grain is flowing past it every second. Combined with a GPS receiver, this creates a continuous record of how much, from exactly where.
After harvest, that data is processed into a yield map: a colour-coded spatial picture of field performance, with high-yielding zones in one colour and low-yielding zones in another. Over multiple seasons, patterns emerge — patterns that point to drainage issues, soil type boundaries, compaction zones, or variable fertility.
Not all yield monitors work the same way. The two dominant sensor technologies have meaningfully different characteristics:
Grain hits a metal plate and the force is measured. The harder the impact, the higher the flow rate. Common in OEM (factory-fitted) systems on John Deere, CLAAS, and others.
A light beam counts or measures grain passing through. Flow is calculated from interruption patterns. Used in the Green Growth retrofit system.
Modern high-spec combines from John Deere, CLAAS, and others can come with yield monitoring built in from the factory. But the majority of working machines globally — especially outside of the largest farms — were never fitted with yield monitoring.
A retrofit yield monitor is an aftermarket kit installed on an existing combine. It adds yield mapping capability to machines that were never factory-equipped with it, and — in many cases — replaces or supplements existing factory systems with a manufacturer-independent platform.
| Feature | Factory-Installed | Green Growth Retrofit |
|---|---|---|
| Compatible machines | That brand only | Any combine, any brand |
| Works on older machines | No (tied to new purchases) | Yes |
| Mixed fleet aggregation | Rarely — brand-siloed | Yes — all machines in one map |
| Data ownership | Manufacturer platform, often locked | Farmer owns data, full export |
| Calibration requirement | Frequent (impact plate) | Minimal (optical sensor) |
| Installation | Factory only | ~2 hours, DIY |
Knowing your total tonnage is useful. Knowing where it came from is transformational.
Yield maps are the foundation of precision agriculture. They reveal spatial patterns that are invisible to the naked eye — a low-yield band tracking the path of old tile drainage, a high-yield patch correlating with a deeper topsoil, a consistent underperformer in the same field corner every single year. Once you see these patterns, you can act on them.
Practical uses for yield map data include:
A yield monitor is a sensor system installed on a combine harvester that measures grain flow continuously during harvest. It records how much crop is harvested from each part of the field, combined with GPS coordinates, to produce a yield map — a spatial picture of field performance.
A sensor on the clean grain elevator measures grain passing through. A GPS receiver records position simultaneously. Machine speed and header width are also tracked. Together these produce a geo-referenced yield reading every second, which is assembled into a yield map after the harvest run.
An impact plate measures the force of grain hitting a metal plate — effective but sensitive to moisture and mechanical wear, requiring regular recalibration. An optical sensor measures grain flow using light — unaffected by moisture and with no moving parts, so it needs little to no recalibration between or during harvests.
Yes. Retrofit yield monitors are designed for exactly this. Green Growth's universal kit works on any combine with a clean grain elevator and 12V power — regardless of brand, age, or model. Installation takes approximately 2 hours.
Yield monitors collect grain flow rate, GPS position, machine speed, and cutting width — and many systems also log grain moisture. These inputs combine to calculate yield per hectare at each GPS coordinate, producing a complete field yield map.
Total tonnage tells you what a field produced overall — not where it came from. A yield monitor reveals the spatial variability inside that total: which zones consistently underperform, where drainage problems reduce yield, where soil changes matter. That spatial information is what makes precision management decisions possible.
Green Growth's retrofit kit installs in ~2 hours and works on any combine — any brand, any age. Optical sensor technology, no calibration.
See the Yield Monitor Kit