What Is Compaction Costing You?

The need for speed to hit an optimum planting window between rains is part of a trend toward larger planters with central fill systems, and larger tractors to pull them.  However, the time savings can come at a cost to plant health and yield if the planting pass adds to soil compaction.

“Soil compacted at planting can inhibit moisture and nutrient movement and stunt plant root growth, making it difficult for the plant to make its way out of the furrow. That’s why it’s important to minimize compaction at planting. It may not be as evident in good years, but it’s an extremely wet or an extremely dry growing season that those stresses really take their toll on the growing crop. Plant scientists at Purdue University, the University of Nebraska and elsewhere report that areas of soybean fields with moderate to severe soil compaction are associated with increased levels of sudden death syndrome.

Whatever the conditions present at planting, experts recommend paying attention to two important factors that growers can have control over: using the right tire pressure for the job, and the choice of tire type used on tractors, planters and other field equipment. With new developments in tire technology and innovations like VarioGrip, the tire pressure system on Fendt tractors, along with new weight-management systems on planters, using tire pressure to manage equipment weight and soil compaction can be easier and more effective than before.

Tires are the contact point between the machine and the ground. So as machines get bigger, they get more efficient and effective, but also heavier, so they also can create more damage through soil compaction. The rule of thumb is that whatever pressure is in the tire, the resulting pressure exerted on the ground is 10% to 20% more than that, Harris says. Excess ground-contact pressure from the tires is what causes compaction.

When possible, use the minimal allowed tire-inflation pressure to carry the known axle load. That gives the biggest footprint, spreads that weight over a larger area, and minimizes the compaction in the soil.

So, it’s important to weigh the axle loads of tractors and equipment such as planters to know the total load configuration. That load, combined with the tire size and the predicted speed of the operation, determine the recommended pressure based on tire inflation tables and/or online calculators from the manufacturer.

Different Jobs Need Different Tire Pressures

Now comes the sticking point for many farmers, as that recommend pressure changes with road speed and application. Ideally a farmer would have a given speed for the road that would allow the tire to be fully inflated; that would allow a completely hard surface across the road, and it would drive and handle well and the sidewalls would be still stiff enough to steer well and stop well.

Then when a farmer gets to the field, they would get out and lower their air pressure to something that would provide a lot longer footprint, a lot more traction in the field, better performance in terms of fuel consumption, and less soil compaction to be much kinder to the fields. But that rarely happens; changing inflation with a normal-size valve takes time that few growers have at planting time, and it means needing an air supply at hand to re-inflate the tires for transport.

In AGCO field clinics, specialists show customers how a 16-row folding corn planter can add anywhere from 10,000 to 15,000 pounds of load to the rear tractor axle. So setting inflation pressures up for road transport, you need 30 to 35 PSI in those tires to carry the load. But when you get to the field open the planter up and we carry the weight on all the planter tires, that load comes off, and you only need 20 PSI.

So without changing the tractor-tire pressure before planting in wet years, a farmer could be running at 35 PSI, but really could be down at 20 PSI, putting 15 PSI more contact pressure into the soil, which could cause pinch-row conditions.

Tire Technology Is One Answer

One solution to soil compaction is technology and tires that allow farmers to reduce the air pressure in tires and the carry the same amount of weight.

Many of those tires are IF (increased flex or flexation) and VF (very-high flexation) tires. IF tires are a radial construction that carries 20% more load than a standard radial tire at the same pressure­. It allows that tire to flex more than a standard radial. A VF tire carries 40% more load than that standard ag radial tire. The tires will look flatter than a standard radial because they’re designed to operate with more squat in them.

So, while a standard radial tractor tire may need 35 PSI to pull a heavy planter on the road by putting an IF tire on that tractor, you can reduce that inflation pressure down into the 20s. It helps us use a lower inflation pressure to do the least amount of compaction into the soil.

AGCO Equipment: Solving the Central-Fill Planter Dilemma

So besides investing in higher-flexation tires and using proper inflation rates, what else can growers do to protect their field and yield at planting time when using central fill planters? The concentrated weight on conventional dual wheels under commodity tanks is known to cause pinch-row compaction and limit yield in center-of-planter corn rows.

As an industry, “we really started affecting planter weight with the introduction of central fill about 20 years ago,” AGCO’s Kuster says. “But do we want to go back to 2-bushel or 3-bushel boxes on each the row, and the time it takes to fill that type of planter? No, we don’t. So how do we handle the weight of the central fill so we can maximize the crop’s potential?”

In developing the Fendt® Momentum™ planter, AGCO’s global engineering team was tasked with designing a new, high-capacity central fill planter from a “clean sheet.” One of the jobs was to figure out how to solve the compaction issue with a new type of weight-transfer system.

The result is the Load-Logic® weight management system on the planter, which lets the operator choose to use a load-balance mode to distribute the weight of the seed and fertilizer evenly across the planter bar, or the controlled-traffic mode to focus the weight on the in-line tandem center wheels that follow the path of the tractor wheels. You can put the weight in the right places, and then the tires adjust automatically using a smart central tire inflation system (CTIS) as part of Load-Logic.

That first comes into play when the operator pushes a button in the cab to unfold the planter, and the CTIS deflates the tires from the pressure needed for 20 mph road transport to the right pressure to plant at 5-10 mph with a full load of seed and fertilizer, up to 20,000 pounds on the Momentum. Momentum will be equipped with VF tires that can carry the weight at lower pressures and elongate to get a huge increase in the tire footprint.

As the seed and fertilizer is dispersed, the tire pressure adjusts even lower (never below 15 PSI) to match the load and avoid unnecessary compaction, then increases as needed after tanks are refilled. AGCO has found in field tests that even on a big planter like Momentum, with all of its capacity and attachments, farmers are running at less than 20 PSI 80% of the time.

On a 2,000- or 3,000-acre farm, it’s something that would probably pay for itself within a season or two, depending on the size of the system, and have immense benefits. And it will pair perfectly with Fendt row-crop tractors with the factory-installed VarioGrip™ tire pressure regulation system. VarioGrip allows the operator to set and control tire pressure on-the-go from 8.7 to 36 PSI to reduce compaction and tire wear while optimizing traction and performance in the field or on the road.