Yield monitoring and harvest sensors

A yield map needs a trustworthy measurement chain

A combine yield map links the crop passing through the machine to where that crop was harvested. Its quality depends on grain-flow sensing, moisture measurement, travel speed, harvested width, position and timing. A colourful map can look persuasive even when one of those inputs is wrong. Begin with calibration and field records before using the map to change fertiliser or seed rates.

Dry yield requires a reference moisture basis. Grain weighed at harvest moisture is not directly comparable with grain adjusted to another moisture content. Record the crop, moisture adjustment, calibration loads and unit convention. Tonnes per hectare and bushels per acre also require the appropriate crop-specific mass convention.

How harvest sensors estimate yield

Impact-based systems relate force at a sensing surface to crop flow. Optical systems observe the material carried by elevator paddles. Neither mechanism makes every crop condition identical: grain properties, elevator mechanics and changing flow affect the relationship between signal and harvested mass. A separate moisture sensor helps express yield on a consistent basis.

The grain reaches a sensor after travelling through the machine. That transport delay means the receiver’s current position may differ from where the grain was cut. The map needs suitable delay settings and a record of effective cutting width. Header-height sensing can help exclude travel with the header raised; an incorrectly recorded partial swath can still distort calculated yield.

Five harvest measurement systems

The systems below span retrofit monitoring, installed OEM measurement and automatic calibration. ActiveYield assists calibration on compatible Deere combines; it is not an interchangeable standalone retrofit for every harvester. Compare sensor installation, supported combine models, displays and export workflow before comparing software features.

Yield kit with matched InCommand display

Ag Leader Yield Monitoring

A combine monitoring system that links grain-flow and moisture measurements with field records. The current product page identifies support through InCommand Go displays.

A retrofit or compatible installed Ag Leader harvest system

Confirm the combine kit and calibration procedure; existing sensors may be reused only where supported.

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Pro retrofit ECU; optional associated sensors

FarmTRX Yield Monitor Pro

A retrofit yield-monitoring ECU with satellite positioning and cellular/Bluetooth connectivity. Its associated moisture and header-height sensors add information needed for a complete harvest record.

Adding yield mapping to a suitable existing combine

Specify the moisture/header sensors and confirm display integrations and service access.

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Clean grain elevator kit; compatible 20|20 required

Precision Planting YieldSense

A clean-grain-elevator monitoring system with matched paddles and flow sensing. Harvest operation does not require an internet connection; later transfer depends on the chosen workflow.

A supported combine using Precision Planting harvest records

Check the exact combine list and display generation; Panorama support differs.

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Automatic calibration on compatible Deere combines

John Deere ActiveYield

A calibration system that uses grain-tank observations to update a compatible combine’s mass-flow measurement. It is an OEM upgrade path rather than a universal standalone monitor.

Reducing manual calibration work in a supported Deere installation

Load acceptance depends on movement, slope and flow conditions; verify crop/model support.

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Grain and commodity yield controller

Topcon YieldTrakk YM-3

A yield-monitor controller for grain and commodity harvest systems. Keep YM-3 grain monitoring separate from YM-2 specialty-crop applications.

An optical yield architecture in a Topcon or compatible terminal installation

The controller alone is incomplete; include optical/moisture sensors and a supported console.

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Calibrate across the flows you harvest

Use the manufacturer’s calibration procedure with a reliable independent weighing method. Check moisture against a suitable reference and inspect elevator chains, paddles, sensor surfaces and wiring. Calibration loads should represent the range of grain flow expected in the crop, rather than only one steady high-yield pass. Recheck after material changes in crop moisture or machine condition.

Purdue’s September 2014 discussion explains that calibration teaches the monitor how its electrical signal relates to grain flow and highlights the difficulty of strongly variable fields. That principle remains useful: a monitor fitted with good hardware can still produce a biased map if the calibration does not represent the harvesting conditions. Follow current model instructions for the actual load count and acceptance criteria.

Inspect the spatial record

Look for abrupt changes at starts, stops and headlands. Confirm that low-yield strips do not coincide with partial swaths, raised-header travel or an incorrect delay. Check the recorded width against actual overlap. Compare field totals with independently weighed deliveries, but also inspect the distribution: agreement in a field total can coexist with misleading local patterns.

For example, 3 tonnes harvested over 0.5 hectares is 6 tonnes per hectare before any moisture adjustment. If the system wrongly records 0.6 hectares for the same mass, it reports 5 tonnes per hectare. That discrepancy comes from area, not grain-flow calibration. Keep the original observations when cleaning a map so that exclusions and corrections can be traced.

Choose a workflow that preserves usable data

Ask whether the quote includes yield and moisture sensors, header sensing, receiver, harnesses, installation, display access and cloud services. Verify how maps and raw records can be exported, what happens without cellular coverage, and whether your agronomist’s software accepts the files. A live dashboard is useful only if it retains the records required for later analysis.

Use several seasons and field observations before attributing a low-yield area to one cause. Drainage, pests, crop establishment and harvest conditions can create similar patterns. Yield identifies where to investigate; it does not identify nutrient deficiency on its own.

From combine instruments to mapped records

Ag Leader dates its yield-monitoring history to 1992. Contemporary systems connect that established sensing job with GNSS and digital field maps, while optical retrofit options and automatic calibration provide different installation paths. Product generations change, so a current kit should be specified by combine model and controller generation rather than by the brand’s history alone.

Terms in a harvest record

Mass flow

Crop mass passing a measurement point per unit time.

Transport delay

Time between crop cutting and its arrival at the sensor.

Calibration load

A harvested quantity with an independently established weight used to adjust the monitor.

Effective swath

The width actually harvested, excluding overlap and uncut gaps.

Does automatic calibration remove weighing checks?

No. Automatic calibration can reduce operator work, but its accepted loads and operating conditions have requirements. Independent weights and a moisture reference remain useful checks. Diagnose differences before changing a prescription, especially when a new crop or machine adjustment changes the sensing conditions.