3   Tracks and Tires

3 Tracks and Tires


Hi, my name is Jodi DeJong-Hughes I work for the University Minnesota
Extension. In this series of videos, we’re going to learn about what is
compaction, how to build a healthy soil to resist compaction, and what equipment and tire choices are
out there to help minimize the effects the compaction in your fields. In September of 2011, the University of
Minnesota Extension partnered with NDSU, commodity groups, and equipment
manufactures to hold a unique field day near Fergus
Falls, Minnesota. Four soil pits were created to demonstrate different management
techniques to help ‘Take Control’ of soil compaction. This
video is the third in a series of four to help identify compaction and manage
it in your fields. Randy Taylor, an ag engineer with
Oklahoma State University, spoke to us about tracks and tires and
managing field traffic to reduce soil compaction.
Soil compaction is generally categorized as shallow or
deep. Shallow compaction is confined to the top six to eight inches of the soil and it’s directly related to the
pressure that is applied to the soil. For tires, your ground pressure is really
close to the inflation pressure. Proper tire inflation pressure is based
on your axle load, number tires, and your tire size. Proper
inflation of your tires is discussed in more depth in video number four of this series. To
calculate the ground pressure for a track, you take the length and the width of that
track and the weight that is supported by that track. It becomes a little more complex when
computing ground pressure for a tracked vehicle because of the bogie wheels. While a track may have an average ground
pressure of 5 PSI, there are pressure spikes under the bogie
wheels, bringing up the average pressure overall. For both tracks and tires, a higher
ground pressure will relate to more compaction than a lower ground pressure. That’s why it’s important to know
whether you have tracks or tires, what kind of pressure is being put on the
soil. Proper tire inflation for road speed maybe two to three times higher than for
proper inflation in the field. Using the road inflation rate in the
field will create more compaction and could
reduce yield. While it can be inconvenient to adjust your tire pressure, it’s worth the hassle to minimize the
compaction potential. One of the advantages to tracks is that there’s no tire inflation
adjustment to make. Deep compaction occurs below 8 inches and is related to the force
applied to the soil or the axle load. More weight on the
axle means deeper compaction. The weight of larger
tractors, combines and grain carts can force compaction down to a depth of
three to four feet. Since depth of the compaction is based on
your axle load, both tracked and tired vehicles can create deep compaction. While they both can
create compaction, there are advantages to each system.
Tires have greater stability, less vibration, lower initial cost, easier
handling on your contours and turning at the edges of the field, and
they have a minimal weight transfer effect. Tracks on the other hand have
better flotation and better ride quality in rough fields.
They have less slippage and no power hop and they have better
fuel efficiency in soft fields. Managing your vehicle traffic is one way
to reduce your compaction. About eighty percent the compaction
happens on the first pass. I’ll repeat that: about eighty percent of
the compaction occurs on the first pass. Use this to your advantage! In a normal
year as much as 90 percent of the field may
be tracked by equipment. If you use the planter, the sprayer, the
combine the grain carts and do tillage passes across the field, these are all
making separate tracks. The philosophy behind controlled traffic is
to restrict the amount of soil driven on by reusing the same wheel tracks or tram
lines. By controlling traffic, the tract areas
meant to be compressed, similar to a road, while the soil between
the tracks is not compacted. The benefits to controlled
traffic are improved tractor efficiency and
flotation, less horsepower needed, improved timeliness of your operations,
reduced skips and overlaps and improved soil quality. The philosophy is different than with
minimizing compaction. Tall narrow tires are important to
minimize the area driven on in the field. Over time you’ll need to line up your
equipment to follow in the combine tracks, such as your planter and sprayer. Also track maintenance and
RTK will become critical. If you want to try controlling traffic
without committing to the entire program, start with the most compacting piece of
equipment in your field, the grain cart. Since most of the compaction
happens on the first pass, try driving your grain cart in the old
combine tracks and head back out to the headlands to
get to the field entrance. Don’t take a diagonal across a field
where you can create eighty-percent more compaction across the field. When harvesting a small field where the
fields are wet or when growing a lower yielding crop
like your soybeans, try unloading at the ends of the field,
instead of on-the-go. Your soil is a valuable resource when
growing a healthy and profitable crop. Understanding the weight and pressure of your equipment and by minimizing your footprint, you are taking control of your soil
compaction.

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