“John Deere’s cotton yield monitor uses microwave energy to measure the cotton’s flow into the ducts. The emitter and receiver are mounted behind the duct, and the reflectance of this microwave energy is used to count how much cotton is coming through the ducts. This requires plastic ducts to operate properly.”

Depending on the model of the yield monitor, sensors may be installed on two, four or six ducts. Cables from the sensors on the ducts lead to the cable of the picker where a user interface console is installed.

“The console receives and processes data from the sensors, displays yield information and yield maps in real time, and stores the data for later use.

Yield data is typically stored in pounds of seed cotton harvested per acre, although the user can choose to diplay yield data in many forms, including bales per acre.

One of the case studies used to illustrate the benefits of yield maps was from Paul Clark Farms in Courtland, Ala., in the Tennessee Valley region of the state. Clark reports as follows:

“We identified a low-yielding area approximately five acres in size in a 58-acre field from cotton yield maps created during 2003 and 2005.

“After the 2005 growing season, we decided to take this area out of production and apply chicken litter and gin trash to it for four years. The area also was planted to grass.

“In addition, we used the yield maps to develop a variable-rate corn seeding map for the field. For variable-rate seeding, we use three rates — 25,000, 27,000 and 29,000 seeds per acre — and planted fewer seeds in areas with lower yields and more seeds in areas with higher yields.

“Our normal seeding rate is 26,000 seeds per acre. We brought the five-acre area back into production during 2010.

“The 2010 corn yield map showed that most of the five-acre area produced about the same yield as the rest of the field. The field was in cotton during 2011, but we were not able to collect yield data.”

The cost of the yield monitor and associated mapping software for Clark was approximately $10,000. About $2,000 was invested for variable-rate seeding equipment.

“Yield maps and yield monitors are very valuable tools,” says Vellidis.

“You can’t document the effects of your management without yield maps. The best way to take advantage of the information provided by yield maps is to convert them to profit maps. This way, you can see the dollars and cents of your management practices.”



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