Agriculture Reference
In-Depth Information
Agri-Plan Corp. released its first cotton yield monitor in 1997 and upgraded the
system in 1998 and 2000. The Agri-Plan monitor used an Agri-Plan 600 console as
a user interface. The FarmScan cotton yield monitor with the Can-link 3000 console
was released by Computronics in 1999. Micro-Track Systems marketed its first cot-
ton yield monitor in 1997. The Micro-Track system used the Grain-Track console and
Data-Track module for yield data collection and storage. Similar to the Ag Leader
system, these three cotton yield monitors had multiple cotton flow sensors mounted
on the pneumatic ducts of a cotton harvester and a console installed in the cab. The
consoles were able to display information such as current yield, total load, ground
speed, a field identifier, and acres harvested. Each system had its own software to
process the yield data (Vellidis et al., 2003). Thomasson and Sui (2000) and Sui and
Thomasson (2002) reported on an optical reflectance-based mass flow sensor (U.S.
Patent No. 6,809,821). This sensor included the light source and detectors in one hous-
ing unit. In operation, the sensor could be mounted on one wall of a pneumatic duct,
requiring only one port to be cut in the duct, and there is no requirement for align-
ment. The Mississippi Cotton Yield Monitor was based on this sensor (Thomasson
and Sui, 2003; Sui et al., 2004). MSTX Agricultural Sensor Technologies (Hearne,
TX) licensed this technology from Mississippi State University and made the optical
reflectance-based mass flow sensor for cotton yield monitor commercially available.
Instead of using optical technology in the cotton yield monitor systems mentioned
above, John Deere used microwave sensing technology to measure cotton flow at
each duct of a cotton picker. The John Deere system requires no holes on the ducts
for the sensor installation.
Each of these commercially available cotton yield monitors has been evaluated
under field conditions (Durrence et al., 1998; Sassenrath-Cole et al., 1999; Wolak et
al., 1999). Results of the evaluations varied from poor to excellent under the given
conditions. In general, they were able to provide a realistic estimate of the yield
variability within a field. A frequently calibrated and well-maintained system may
estimate the weight of a basket load with an error about 5% (Vellidis et al., 2003).
Cotton yield monitors must be calibrated according to manufacturer recommen-
dations for accurate measurements. Typically, three loads are harvested, with the
yield monitor operating and collecting data, then weighed with a certified scale.
Load weights are entered into the yield monitor system to calculate a calibration
index. The yield monitor then uses the index to determine the yield estimate. For
best performance, cotton yield monitors should be recalibrated when field condi-
tions such as cotton variety and yield present major changes. Because the cotton
flow sensors used in all the aforementioned cotton yield monitor systems (except
John Deere's system) are optical devices, and the seed cotton contains trash when it
is harvested, the optical window of the sensor can be contaminated as seed cotton
passes by the sensor. Thus, the cotton flow sensors should be carefully maintained
and cleaned on a daily basis.
Sui et al. (2004) developed a data post-correction method for cotton yield data
processing. This method uses the total field lint weight as measured at the gin and the
integrated sensor output from the field to calculate a ratio of cotton weight to sensor
output, known as the calibration coefficient. Yield at each field location is adjusted
with the calibration coefficient before generating final yield maps for the field. This
