Extension Ag Update
November/December 2003
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Improving Safety for Transport of Hay Bales, RIRDC Pub. 03/120 http://www.rirdc.gov.au/reports/FCR/03-120.pdf

Robert Di Cristoforo and Dr. Peter F. Sweatman, 03-9334-7888, peter@woaduser.com.au, Victoria, Australia

In recent years, there has been a significant increase in the volume of hay moved and an increase in the number of accidents involving vehicle rollovers or hay falling from trucks. This study, conducted in Australia, aimed to provide a sound technical basis to aid in the loading and moving of bales. Tests revealed enormous variations in lateral rigidity between the different types of bales, with round bales offering the least rigidity. The 4ft x 4ft x 8ft rectangular bales were by far the best performers, with more than twice the rigidity of round bales at 4.6m high. Oct. 2003.


Tractor Tire Needs May Vary in No-Till and Conventional Farming Systems

David Elstein, ARS News Service Agricultural Research Service, USDA, (301) 504-1654, delstein@ars.usda.gov

Farmers who do not till their land may need different types of tractor tires in the future to minimize soil compaction, according to a study by the Agricultural Research Service. Compaction is caused by the weight of the tractor tires pressing down on the soil. When operating tractors, farmers try to minimize compaction because it can hinder infiltration of water to crop roots and increase soil erosion and water runoff.

Thomas R. Way, an agricultural engineer with ARS's National Soil Dynamics Laboratory in Auburn, Ala., led the study in cooperation with Tadashi Kishimoto at the Obihiro University of Agriculture and Veterinary Medicine in Japan. In the study, the researchers used a tractor tire equipped with six sensors on its tread to study tire pressure on tilled and no-till soils. Surprisingly, they found that the pressure was least uniform on untilled clay soils, and was actually more uniform on tilled soils. This research is expected to help manufacturers adjust the tire contact pressure and the size of tire lugs. The lugs have considerable contact with the soil and they also can affect compaction. Changing tire pressure and size could help minimize compaction on no-till fields.

Researchers were also surprised by the similarity of another factor called "tractive efficiency" on tilled and no-till soils. This is a measure of the efficiency with which the tire converts the power that's applied to the wheel to useful work. A tractor's fuel efficiency increases with its tractive efficiency. The study showed that tractive efficiency was the same on tilled and no-till soils, meaning there was actually little difference in fuel efficiency.


"Sewing" the Soil: A Quicker Way To Measure Soil Compaction

David Elstein, ARS News Service Agricultural Research Service, USDA, (301) 504-1654, delstein@ars.usda.gov

A new device developed by an Agricultural Research Service scientist may be the best yet for measuring soil compaction, which causes problems for farmers by preventing moisture from seeping down to plant roots. Compacted soil also increases water runoff and wind erosion.

Agricultural engineer Randy L. Raper of the ARS National Soil Dynamics Laboratory in Auburn, Ala., has led the development of technology, in cooperation with Auburn University, that uses one sensor to measure soil strength at all depths in the top 18 inches of soil. Raper's invention is known as OMIS (for On-the-fly Mechanical Impedance Sensor).

OMIS isn't the first device developed to measure soil compaction. Scientists have developed and tested several others, but those only measured soil at a few depths. Often this isn't sufficient where compaction varies throughout each field and may be caused by a thin hardpan. Hardpan is a dense layer of soil that restricts root growth and the movement of moisture, air and beneficial organisms through the soil. So farmers need to check compaction at various soil depths, not just the few that other devices measure. Raper’s invention consists of a sensor attached to the front of a shank. As the shank is pulled by a tractor through the field, it is moved up and down like a needle on a sewing machine. As the tractor moves forward, the sensor is cycled up and down to measure the soil strength.

Farmers can use Global Positioning System technology to create soil compaction maps and adjust their tillage depths. OMIS could also be customized to measure other properties, such as electrical conductivity and the amount of moisture in the soil. Raper is continuing to improve the technology for field use and hopes the new invention will be on the market in a few years. A patent application has been filed, and ARS is looking for a licensee to commercialize the device.