Feed mill sensor technology is now headed for combines.

An electronic sensor used in feed mills to measure density and moisture of feed is being adapted to combines to give a farmer the same measurements on crops as he drives down the field.

The sensor, developed by AgriChem, works in conjunction with a combine's existing yield monitor. "With different varieties, hybrids and genetically modified grains, the more we know about what we are harvesting the better we can put a tag on that material when it goes into the bin," says Dr. Jonathon Chaplin, agricultural engineer at the University of Minnesota, who tested the product.

Quality indicators. So why is knowing density and moisture of grain, in particular, so important? Moisture is an indication of how well the grain will store. If it is too high in moisture, it needs to be dried before being stored or it will spoil. Existing yield monitors can measure moisture, but not as well as the new sensor can, according to Dave Greer, president of AgriChem.

Density, or "test weight," is an index of the percentage of starches and sugars present in the grain that give the grain value as feed, alcohol or other end uses. "For instance, 60-lb. corn is good stuff, 50 lbs. is not so good," Greer explains.

Elevators rely on these measurements to determine whether to accept or reject your grain. But knowing them yourself gives you several advantages, Greer says.

One advantage is that it can help you negotiate a fair price for the grain when it comes time to sell. "If you know what you have when you go to sell it you are in a firmer position than if you are relying on trying to sell it to the person who is appraising it for you," Greer says.

Another advantage is that it can help you sort grain during harvest. For example, if you come to a patch of grain that is high in moisture, you can skip over that area to give it more of a chance to dry in the field, thereby saving on drying costs.

Or if you are growing grain on specification and an area is below the density required by the buyer, you can put that grain in a separate truck and reroute it to a different point of sale where it will be accepted. That saves on transport costs.

How it works. The sensor, which works off of a combine's 12v power system, is mounted on the clean grain auger of the grain tank. The grain passes through a test cell where both its moisture content and test weight are determined electronically. The location of each reading is picked up by a yield monitor's Global Position-ing System.

All of the information is sent to a touch-screen display module in the cab for processing and storage. The data can be downloaded to an office computer. Using GIS mapping software, the density and moisture levels throughout a field can be mapped toshow what management actions need to be taken.

Field tested. Last year a prototype was mounted on a John Deere 9510 and tested by the University of Minnesota on 1,500 acres of corn, soybeans and wheat. Researchers included Dr. Jonathan Chaplin and assistant scientists Todd Hustrulid and Brian Hetchler. The sensor is capable of density readings of +_1/2 lb./bu. and +0.2% for the moisture readings, according to the researchers.

AgriChem is now working on packaging the sensor to be sold as a retrofit kit for combines as early as crop year 2001. Cost is expected to be about $3,000 to $4,000 compared with $40,000 to $50,000 for the equipment used in labs. The company also is talking with OEMs about the possibility of factory installing the sensor on new combines.

The University of Minnesota also is working on developing a new yield monitor that can provide readings of grain mass that are more accurate than those possible with existing monitors and that will work in conjunction with AgriChem's sensor.

For more information, contact AgriChem Inc., Dept. FIN, 15760 Lincoln St. N.E., Ham Lake, MN 55304, 800/533-4385.