After a wet spring you don’t need to tour very many corn fields to find evidence of compaction problems. Drowned – out, yellowed and uneven corn in the headlands and in areas across the field that obviously received more wheel traffic than the soil conditions could handle. Some pretty interesting patterns can show up after a few week of above average rainfall. Was that the manure tanker that went on that funny angle across the field or the tracks from field cultivating when it was a bit on the wet side?
How can we best solve the compaction problems created in wet springs? One solution may be to use deep tillage to break up the soil at depth. However, U.S. and Ontario studies have had a difficult time showing and conclusive advantage to deep tillage. In some cases deep tillage breaks up macropores which corn roots can use to explore the soil profile for water and nutrients. Planting deep – rooted legumes such as alfalfa encourages macropore development and helps mitigate compaction problems.
The best solutions for compaction however, are probably those which help to prevent it. Besides agronomic measures, such as using crop rotations that encourage good soil structure and simply staying off wet fields, other mechanical measures can be taken. Reducing axle loads and tire inflation pressures, and increasing the tire footprint by using larger tires, duals or tracks are all good methods to reduce (but not eliminate) compaction. One more solution, which
combines both careful agronomic and mechanical management is to use tramlines. As much as 90 % of a conventionally tilled field may be covered by tire tracks in one year. Since 70 – 90 % of compaction in the plow layer occurs on the first pass, it is best to limit the field area exposed to wheel traffic. Tramlines effectively reduce the potential area for compaction to a small percentage of the field.
Chris Boersma, of Ridge Valley Farms near Ridgetown, Ontario has been using tramlines since the late 1980’s. Chris, his brothers Mark & Dave, and father George, started the system in their soybean crop to aid in post – emergent spraying and then kept the tramlines when they switched to narrow-row corn in the early 1990’s. They converted their 8 x 38 inch row corn planter to a 13 x 19 inch row unit, leaving two 38 inch row spaces in the centre, to line up behind the tractor wheels. Seed openers in the 7.5 inch row soybean air seeder are blocked behind the tractor wheels, so that the same sprayer, which Chris built, can follow the tramlines in both crops. A GPS guidance system is used during planting, which ensures that the tramlines are in the same place for corn and soybeans. Including custom work, 2 500 ac were planted with this system in 2004.
Chris Boersma, Ridgetown Ontario, looks to controlled traffic |
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to reduce compaction and improve field efficiencies |
A unique corn planting pattern of course necessitates a unique corn harvester. No 19 inch row corn heads were available for their John Deere combine in the early 1990’s, so the Boersmas visited with a J.D. engineer in the Quad Cities, Iowa. They came home and built the header themselves with the parts sent from John Deere. The corn header also works in their custom harvesting business for their customers who plant in 38 inch rows. They were very pleased with the amount of downed corn they could pick up in the ugly harvest of 2003 with this header!
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While a new corn header was a significant, one-time cost, switching to narrow-row corn with tramlines brought other significant and recurring cost-savings. Now adding all the corn’s nitrogen with the planter as anhydrous ammonia allows planting and fertilizing in one pass. All of Boersma’s fields are scouted regularly, by driving a pick-up truck along the tramlines. This careful scouting has allowed them to cut back and shave rates on herbicides. The tramlines also ensure that misses or oversprays are rare. Chris doesn’t mind spraying late at night or when he’s tired, since with the tramlines, “You don’t have to think, you’re always right on!”
Corn planting populations for one row on either side of the missed row are increased by 15 % to take advantage of the added sunlight and to encourage the canopy to fill in quickly. Chris figures that with this system, his corn yields have increased by 4 – 6 % on their best ground and by as much as 20 % on their poorer (clay) soils.
Chris knows compaction can be a problem on the clay ground in wet years, but is glad that it is confined to the tramlines. So far, their wheat crop is planted without tramlines (that may change if spraying for diseases proves to be necessary). Chris has noticed the previous year’s tramlines in the wheat if the previous year was wet. Tillage is performed after a wheat crop, then the tramlines are started again in corn and kept for the no-till soybeans. The Boersmas are diligent about checking tire pressures with a digital gauge to ensure that the recommended pressures are set for each piece of equipment. They also look for the biggest tires available for equipment and run a 20.8/38 or larger rear tire on all their tractors. Each of these measures work well with the tramlines on Ridge Valley Farms to minimize compaction.
While tramlines give easy visual cues, controlled traffic farming can also be achieved with GPS guidance systems. In his presentation at the Southwest Ag Conference in Ridgetown in January, Clay Mitchell of Iowa described how he uses a Trimble Ag GPS AutoPilot on his 1000 ac of corn and soybeans in Iowa. All of his equipment is set up on 120 inch wheel spacings and his crops are planted in 30 foot strips. This way, only 16 % of the ground is trafficked. Thus, the # 1 benefit to controlled traffic farming is increased yields due to less compaction. Clay Mitchell reports on his website that his yields average 8 % higher than the rest of the county. The number 2 benefit is more efficient machinery operation, since traction is better on soil that has already been traveled upon. His autosteering system gives 1 inch accuracy, thus the exact same paths are traveled all season. With overlaps eliminated, his anhydrous use alone has dropped 20 % and driving in traffic lanes reduced fuel use by 30 %.
Such savings are not uncommon in Australia, where controlled traffic is a popular system to reduce compaction. There, fuel use is reported to decrease as much as 40 % with controlled traffic. Simply reducing overlap can save 5 % for each input and using guidance systems to improve accuracy can increase this savings by another few per cent.
Soybean production in traditional narrow row areas may also see increased benefits from tramlines if one considers the future possibility of in-crop applications of herbicide, fungicide, and insecticide.
Whether you want to set up controlled traffic using tramlines or GPS guidance systems, Randall Reeder of Ohio State University recommends starting with a basic equipment width to set up a swath. Then, match the tire size and spacing for all machinery to minimize the number of passes in that swath.
Narrow row corn with tramlines; yields up, |
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spraying headaches down. |
