One advantage proponents of no-till have championed for years is getting on their no-till fields without making ruts long before their neighbors in conventional tillage can run. Sometimes there's a day's difference after a heavy rain. As it turns out, that's a mixed blessing.
"It's a fact that you can run on no-till quicker after a rain without making ruts, no question about it," says Gary Steinhardt, a Purdue University Extension soil scientist. "The reason it works is because no-till fields have excellent load-bearing capacity. You would cut ruts or get stuck in a conventionally tilled field when you could go right on in no-till. You're not going to get stuck."
Steinhardt was one of the first Extension researchers to study soil compaction. His work dates back to the early 1980's. Unfortunately, soil compaction is not black and white. There are tendencies, however. Steinhardt can provide input that may help you make better decisions.
For example, just because you're not making ruts when you drive the combine across no-till ground doesn't mean you're not doing damage, the soils specialist emphasizes. "That's the other side of the mixed blessing," he relates.
"You may not think you're doing damage, but you could be compacting the surface layers in that no-till situation," he explains. The reason is that while no-till will hold up machinery due to excellent load bearing capacity, it will still compact.
"In no-till your advantage is in those top few inches," he continues. "So you need to be very careful about driving over them when you know it's wet. If you create soil compaction, you lose the advantages of better infiltration and other pluses."
Staying out of the field until the soil is totally dry may not be an option. It certainly wasn't in 2009. However, Steinhardt suggests being very careful and thinking through your options before you run on no-till soils 'just because you can.'
One suggestion is to rethink how you position carts. Even if they stay on top and don't cause ruts, they may still damage the upper part of the profile. Running the cart through the field to catch the combine just to gain time may not be worth it if soils are wet."The other thing you can do is to control traffic patterns during the entire season," Steinhardt says. "In long-term tillage plots at Purdue, if you don't run over the soil in no-till situations, the soil that never sees a wheel track is an excellent place to grow crops.
"Where the tires run, it will be compacted. But the theory is that if you can run as much as possible in the same tracks, then you've got a great area for growing things."
The late Sam Parsons, a Purdue Extension ag engineer, experimented with designs for controlled traffic as far back as the early 1980's. While it fit ridge-till systems well and fits fall strip-till today, it takes more planning in no-till. However, it can be accomplished if you think through wheel spacing, and if you're dedicated to keeping traffic in the same place each time, Steinhardt concludes.