Agriculture Reference
In-Depth Information
services that can be used in cotton including soil sampling, yield monitoring, VRA,
satellite imagery, and soil electrical conductivity (EC) mapping.
6.2.1 C
OTTON
Y
IELD
M
ONITORS
Crop yield is a key factor in determining farm profit. Localized crop yield measure-
ment is the principal requirement in determining profit on a spatially variable basis.
Yield monitors that incorporate a GPS receiver tie crop yield to specific field loca-
tions so that yield maps can be made. A yield map is able to visually indicate the
variability of crop yield over a field and can be used to determine the feasibility for
PA practice in the field. In applications of PA technology, a set of spatial yield data
is one of the most essential elements used to optimize inputs and maximize farming
profits.
A cotton yield monitor is an electronic device that measures and collects cotton
yield data as cotton is harvested with a cotton harvester. A cotton mass flow sensor
is the core technology in a cotton yield monitor system. Several optical sensors for
cotton flow measurement have been developed and used for cotton yield monitoring.
Wilkerson et al. (1994) developed an optical attenuation-based sensor to measure
cotton flow. This sensor was significantly modified and improved (Moody et al.,
2000; Wilkerson et al., 2002) and marketed as the Ag Leader (Ames, IA) cotton
yield monitor sensor. Agri-Plan (Stow, MA), FarmScan (Perth, Western Australia),
and Micro-Track (Eagle Lake, MN) also manufactured commercial optical cotton
yield monitors using attenuation-based optical cotton-flow sensors. All of these sen-
sors were based on the same principle and are similar in configuration and opera-
tion. Each sensor unit has two parts: a light emitter array and a light detector array
mounted opposite each other on a pneumatic duct. The light-emitter array functions
as the light source, and it consists of light-emitting diodes (LEDs) in some configura-
tion. The light-detector array functions as a light receiver, and it consists of photodi-
odes in some configuration. The sensors measure light attenuation caused by cotton
particles passing through the duct. Thus, their installation requires two ports to be
cut in the duct and proper alignment of the light-emitter array and a light-detector
array (Sui et al., 2004).
The first Ag Leader cotton yield monitor system was released in 2000 and con-
sisted of multiple optical mass flow sensors and a PF3000 data acquisition unit.
The PF3000 was installed in the cab of a harvester and communicated through an
RS-485 serial bus to collect and process signals from the sensors and calculate the
yield. Used with a GPS receiver, the data unit was able to record the yield data and
GPS data on a memory card for subsequent creation of yield maps. The PF3000
displayed yield, load weight, ground speed, harvested area, etc., and allowed users
to enter setup values for the monitor system and perform system troubleshooting
(Myers, 2000). Software was provided by Ag Leader Technology for processing the
yield data and creating the yield map. In 2007, Ag Leader Technology upgraded the
system by replacing the PF3000 with an InSight display that includes a 10.4-in color
touch screen and maps cotton yield on the go. A CAN (Controller Area Network) bus
was implemented for data communication between the sensors and the data unit in
the upgraded model (Moody et al., 2007).
