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College of Food, Agricultural, and Environmental Sciences


Wet Spring Ideal to Practice Controlled Traffic

May 29, 2002

COLUMBUS, Ohio - Practicing controlled traffic may afford growers a planting advantage at a time when wet conditions are keeping most farmers out of their fields.

Randall Reeder, an Ohio State University agricultural engineer, said growers who practice controlled traffic might be able to get their crop in the ground quicker despite wet conditions that would delay normal planting.

"Growers who have established controlled traffic techniques could possibly plant several days ahead of those growers who do not have controlled traffic," said Reeder. "If a grower is not using controlled traffic, he has to wait until the ground is dry enough to drive on it, even though the inch and a half seeding depth might be dry enough to plant."

Controlled traffic is a method to manage soil compaction, whereby all farm equipment is the same width so that traffic is confined to specific paths year after year, and the remainder of the soil is untouched. Controlled traffic is usually matched with conservation tillage systems, although the technique can be practiced in conventionally tilled fields, as well, with the aid of guidance systems and GPS technology.

Reeder said controlled traffic offers growers some planting advantages during a wet spring.

"A year like this the soil is going to get compacted very easily," said Reeder. "But if a grower has been practicing controlled traffic for, say three years, the driving lanes will be firm, but the untouched soil will be loose and dry out faster, giving growers the opportunity to plant earlier."

He said that the method works well during times of scattered rainfall, where a day or two of showers is followed by a few sunny days, then more rain. " If a grower is not in a controlled traffic situation, he could be waiting to plant for two weeks," he said. "But with controlled traffic, a grower could be able to plant two days after a rainfall before the next rains come in."

That quicker planting could add up to better yields, especially in a situation, such as this spring, where growers are three weeks behind the planting schedule and the window for corn planting is coming to a close.

"Farmers, as a whole, spend a lot of effort and money to get corn planted early. For example, switching from a six-row planter to a 12-row planter, or trading a tractor with tires for a rubber tracked vehicle," said Reeder. "Think of controlled traffic as just another management option to consider, and this is a year the advantage of controlled traffic in timely planting really shows up."

Not only does controlled traffic give growers a jumpstart on planting, the practice also affords growers spraying and harvesting advantages, as well as long-term ideal soil conditions for plant growth.

Research has suggested that compaction affects crop yields, because compacted soils shut out necessary water and nutrients, leading to poor root development and subsequent poor growth performance. Ten years of Ohio State research on Hoytville silty clay loam showed that through compaction, 10 percent to 15 percent of the crop was being left in the field, adding up to thousands of dollars in lost profits for large growers.

"The aim of controlled traffic is to minimize the amount of soil that gets driven on, eliminating compaction where plant roots are growing," said Reeder. "The average farmer will drive on three-fourths of the field in a two-year period. With controlled traffic, anywhere from 50 percent to 80 percent of the field never gets driven on and that includes 100 percent of the soil under a corn crop."

Despite the advantages of controlled traffic, transitioning to such a system can take time or money, or both. Getting all equipment the same width is the top priority, and minimizing the number of traffic lanes is next, said Reeder.

"A typical farmer is going to have equipment with mismatched widths - for example, a 30-foot planter, a 24-foot drill, a 15-foot combine head for corn, a 20-foot grain platform and a 50-foot sprayer," he said. "If that farmer wants to switch to controlled traffic, he could do it gradually as equipment wears out and is traded in. It might take five years, but the cost would be minimal. Switching everything overnight could be expensive."

He added that the perceived benefit of controlled traffic does not always equal the perceived cost. "Farmers might say, 'Well, that's a lot of trouble and I'm doing alright'," said Reeder. "What they really need to consider, though, is how much compaction is costing them in yield, and then realize that controlled traffic over the long-term will be beneficial."

The following are some general tips farmers should follow when making the transition to a controlled traffic system. Reeder said some adjustments may be harder to make than others.

* Decide on the basic width. For example, 30 feet is the widest width for a combine.

* For equipment that does not fit the basic width, trade for new equipment that does match, over the next few years.

* A sprayer will likely be two to three times the basic width. So if the combine width is 30 feet, the sprayer width should be 60 or 90 feet.

* Select a grain platform the same width as the corn head on combines. Grain platforms are typically wider than the corn head in order to use the combine to its full capacity when harvesting different crops. There will be some loss of efficiency harvesting soybeans and small grains.

* Buy a drill the same width as the planter. Reeder said many drills are not as wide as the planter because farmers generally perceive timeliness of planting more important for corn than for soybeans.

* Choose a combine with tires that match the row spacing so that one is driving on the least amount of soil. Use split duals or possibly, tall single tires. For no-till or mulch-till systems, tire width can be four inches less than row width. In ridge-till, the maximum recommended tire width is eight inches less than the row width.

* Fertilizer applicators must also match the width, or a multiple of it.

* Match grain cart tire spacings with the combine and run the cart in the same tracks as the previous pass of the combine.

* Use a systems approach. Controlled traffic may show ideal results in combination with improved drainage, a GPS guidance system, and continuous no-till.

Candace Pollock
Randall Reeder