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Managing Compaction with Auto Guidance

Most producers look at an automated steering system as a way to reduce overlap and fatigue while conserving fuel, crop inputs, and labor. Fortunately, Tim McGreal, who farms a little over 3,000 acres near Chatsworth, Illinois, has seen all of those benefits since he started using an RTK guidance system approximately nine years ago. In fact, he is so hooked on automatic guidance that he now insists, “If I have to drive it, I won’t do it.”

Bonus benefit from auto steer
However, McGreal has more recently realized an additional benefit of automated steering – managing field compaction.

“I’m about 80% strip-till, so I’ve been using a satellite-assisted steering system on virtually all of my equipment to develop a controlled-traffic situation,” he explains. “That is particularly the case in the fall when I make the strips and the following spring when I plant and apply chemicals and fertilizer. My strip-till unit, planter, and sidedress bar are all 60 feet wide, so I’m on 60-foot tramlines,” he relates.

The guidance system includes a tramline feature, which lets McGreal store and reuse the same A-B lines or wheel tracks year after year, whether he plants soybeans or corn in the 30-inch rows.

“Because my self-propelled sprayer is 120 feet, I can use the same wheel track for weed control, since everything is on 60-foot centers,” he adds. “The only time I don’t follow the tramlines is during harvest. That’s because I can’t run on 60-foot centers with a 12-row machine.”

In an attempt to further reduce compaction, McGreal has begun installing drainage tile directly below the tramlines using the waypoints from his guidance system in combination with a tile plow.

“The idea is to try and suck some of the moisture out from under those tracks as quickly as I can to further reduce the chance of compaction,” he says. “I’ve only done portions of four different fields, but I still want to put down more tile where topography permits it. I don’t require much drainage with my soils. In most cases, a tile every 60 feet is enough to handle the whole field. I may split it with an extra line in the bottoms, but that’s plenty.

“When I drive a 40,000- pound machine across the field, I’m going to have compaction, even if the ground isn’t wet,” he continues. “The tramlines and tiling don’t necessarily eliminate it, but it does give me a way to manage compaction. I know where it is and I’m able to work around it.”   

The other part of the compaction-management equation is his 24-row planter, which has been equipped with the Hydraulic Down Force system.

Other added features include individual clutches on the planter row units and automatic sectional control of the fertilizer units, since he applies both starter fertilizer and insecticide with the planter. Those products are carried in a liquid cart on tracks that is pulled behind the planter, thereby taking the weight off the planter itself.

“Seed placement was really good, but I’d say the biggest benefit of the Hydraulic Down Force system was its ability to change so quickly to match the conditions,” he says.

In the past, he had used a pneumatic downforce system.

“Last year, which was the first year I used it, I had a lot of clods and tough soil, so soil conditions changed rather often as I went through the field. Yet, when I’d look back at the row units, they moved up and down very smoothly. The amount of downforce recorded through the field ranged from 2 pounds to 235 pounds on my best field, while other fields saw pressures range from 50 pounds to 400 or more. Even with my controlled-traffic program, it’s surprising to see how much difference there is from one area to another.”

In the meantime, the individual row clutches, which are controlled by the GPS monitor, have been equally valuable, even though he just started using them last year.

“Most of my fields are pretty square, so I’m not really using the automatic row shutoffs for point rows,” he explains. “I do have a lot of corn-on-corn, and any time I have two rows doubled up, I end up with twice the amount of residue. It may not be an issue under conventional tillage, but when I’m strip-tilling, even two-row section control can lead to extra residue on the ends,” he says, noting that some fields have been in continuous corn for six to seven years. “That’s why I’m using individual row clutch control.”

On the other hand, McGreal is still experimenting with variable-rate seeding. “I was skeptical when I gave it a try this past year,” he admits.

That’s part of the reason he started with a trial, which involved planting part of the fields with a variable-seed rate, while other portions of the fields were planted with a straight rate that ranged as high as 38,000 seeds per acre within a block that saw the highest yields in the past.

“I’ve seen enough of a benefit, though, that I plan to continue. Most of the variation was within 6,000 to 8,000 seeds per acre from top to bottom,” he says, noting how that put populations between 28,000 and 36,000. “I’ve toyed with straight rates up to 36,000 seeds per acre in the past, but I’ve never been really satisfied with the results. I think part of the problem is I put those high rates on areas where they really shouldn’t have been.”

Backed by data
McGreal isn’t lacking on data to back him up, either. With help from his brother-in-law, J.D. Skaggs, who recently joined the operation full time, McGreal has developed a side business that involves gathering and charting data for area farmers and writing input prescriptions for variables such as lime, seeding rate, and fertilizer rate. Extensive records on his own farm include seeding rates, applied downforce on the planter row units, fertilizer rates, soil types, plant varieties, herbicide and fungicide applications, and crop yields.

“I take several things into account on the variable-rate seeding rates,” he says, “but the prescription is primarily based on yields over the past five years.

“One of the slogans when I made the move to RTK was, ‘I want RTK to pay, not cost.’ My goal is to find the best ways to utilize GPS technology for improving my profits and not just use it as a convenience,” he says.

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Tim McGreal

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