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Soil compaction can cut forage yields

By Jim Smith
SUN Columnist

Have you ever driven by a golf course and saw the lawn crew aerating (removing plugs) in the fairways?

Hopefully, you aerate your own lawn.

Soil compaction is the most common problem in lawn quality. CSU Extension Master Gardeners know that soil compaction is the primary factor limiting plant growth in landscape soils.

Many farmers are aware of compaction and hard pans in the soil. Research has shown compacted soils can cut crop yields as much as 50 percent due to reduced oxygen, changed soil structure that inhibits water infiltration, and increased resistance to root penetration. Soil tilth refers to the soil’s general suitability to support plant growth due to a balance of air, mineral, water, and organic matter. An ideal Western soil has 25 percent air, 25 percent water, 2-5 percent organic matter and 45-49 percent mineral solids.

Many of our pastures may have soil compaction, caused by many years of grazing and haying operations. This can be influenced by the soil texture class, organic matter, grazing when the pastures are muddy, excessive hoof traffic, and climate conditions in a particular year. Compacted soil layers interfere with the development of grass roots by reducing the soil pore volume which results in less space for air and water in the soil. Roots that are unable to penetrate the hard pan can develop into a condition call “pancake” effect. The roots spread horizontally and are unable to use moisture and nutrients below this layer. This interferes with the development of grass fibrous roots. Also, compacted soils can affect nutrient uptake and induce nutrient deficiencies. Compaction can make drought conditions more severe as well as inhibit drainage in wet conditions.

How do I know if my pastures have compaction issues? Several methods can be used to determine the severity of compaction.

The first thing that I would suggest doing is taking a soil test to see how much clay and organic matter you have in your soils. If the soil is high in clay and low in organic matter, this makes the soil more susceptible to soil compaction. To test for compaction, drive a steel or wood stake at least 18 inches in the ground next to a fence in soil that has not been tilled or has had traffic on it for several years.

Then, drive the stake in several areas into the pasture where you might suspect soil compaction. Count the number of hammer blows needed to drive the stake to the 18-inch depth and compare the resistance of each place tested. Many agriculture supply companies sell a tool called a cone penetrometer to test for soil compaction. The tool measures the force required to push the steel cone into soil when the soil is near its field capacity water content. The occurrence of bluegrass or foxtail is a very good visual indicator that soil is compacted.

The question is, “What can I do to correct the problem of compaction in my hay fields?”

The answer is aeration with mechanical equipment.

One piece of equipment that I know that works well is the AerWay Shattertine. Also, Landpride makes a shattertine aerator. The machine can be leased for $175 per day and it takes a minimum of a 60 hp tractor to pull it. The machine has tines that crack and shatter compacted soils 8 inches or deeper. The angle of the tines can be adjusted as well as the rollers that hold the tines. The tines lift and shatter the compacted soil sideways and downward. Shattertine aerators work most effectively when soil is on the drier side; the compacted soil won’t “shatter” if it is too moist. However, if the soil is bone-dry and highly compacted, it can be difficult to get the shattertine to penetrate very deeply. So, the soil moisture level has to be “just right” — on the drier side, but not excessively dry.

The Southern Ute Tribe’s Agriculture Division has used this machine for the past two years. They are reporting decreased compaction, improved irrigation water movement through the soil profile, a reduction of undesirable grasses and improved desirable grass density. When water and oxygen penetrate the soil profile, grass roots become more robust and healthy. This results in healthy plants that produce more pounds per acre. Also, they are reporting that irrigation sets are taking longer because the water is penetrating the soil better.

With rising input costs, reductions in available water to irrigate pastures and uncertain weather conditions, producers need to use all available production resources they can in order to make a profit. I’ve outlined one important production tool to use. Two other important production management practices that I would suggest are to soil test to see how much fertilizer to use and have a good weed control program. All of these practices will extend the life of pastures and increase forage production.

Property management workshop

The Archuleta County Weed and Pest Department, along with the CSU Extension Office, are excited to offer the community a property management workshop on March 27.

The workshop will be held at the CSU Extension office at 344 U.S. 84.

Please preregister by calling the CSU Extension office at 264-5931 before March 18.

Presentations will include Chemical Modes of Action, Forest Health/Insects and Disease, Poisonous Plant ID and Animal Symptoms, Applicator and Public Safety, and Property Improvement Methods.

Lunch will be served for a fee of $5.

 Calendar

Feb. 21 — Colorado Master Gardener Program, 9 a.m.

Feb. 21 — 4-H Poultry project meeting, 4 p.m.

Feb. 22 — 4-H Cake Decorating project meeting, 2 p.m.

Feb. 22 — 4-H Cloverbud project meeting, 2 p.m.

Feb. 23 — 4-H Dog project meeting, 10 a.m.

Feb. 25 — Back To Basic Food Preservation, 1 p.m.

Feb. 25 — Back To Basic Food Preservation, 6 p.m.

Feb. 25 — Livestock Committee, 6 p.m.

Feb. 27 — 4-H Sports Fishing, 4 p.m.

Feb. 27 — Archuleta County Fair Board meeting, 6 p.m.

Feb. 28 — Colorado Master Gardener Program, 9 a.m.

Feb. 28 — 4-H Lamb Project meeting, 4:30 p.m.

Feb. 28 — 4-H Goat Project meeting, 5:30 p.m.

Feb. 28 — 4-H Swine Project meeting, 6:30 p.m.

March 1 — 4-H Winterfest Party, 6 p.m.

March 2 — 4-H Dog Obedience Project meeting, 10 a.m.

Check out our webpage at www.archuleta.colostate.edu for calendar events and information.

Colorado State University, U.S. Department of Agriculture, and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

This story was posted on February 21, 2013.