Dean Sponheim calls himself the "accidental conservationist."
"We’ve implemented a lot of different things that ended up being conservation practices, but they didn’t start out that way," Sponheim explained on his farm near Nora Springs.
Sponheim really began implementing conservation practices on his farm in 1999. But then, the practices weren’t really considered conservation practices; they were simply different methods of farming.
Now, the Pioneer seed dealer is considered to be a leader in conservation.
"We got started strip tilling because it was a niche; it wasn’t a conservation effort at that time," he said. "Even though they (experts) had been telling us it was going to be a conservation practice, that’s not why we started."
Sponheim started using strip tilling practices on his farm because he had fields with very little drainage tile but very high clay content.
He started investigating ways he could make his fields more productive and discovered strip tilling.
Strip tilling on the Sponheim farm means he and his son, Josh, (pictured together above) lay an 8-inch-wide strip in the field. The strip is 7 to 9 inches deep. "We actually place fertilizer at the bottom of the trench so all we’re doing is tilling that small area," Dean said.
They started a custom strip tilling business in 2004. Strip tilling replaces the fall tillage pass, Dean said. And they don’t cultivate in the spring.
"And we leave the residue on top so it acts as a cover," says Josh, Sponheim’s son. He’s a precision ag data analyst for Premier Crop Systems.
They said strip tilling helps preserve the soil, and they see less erosion. "We have very little dirt exposed for a winter erosion. And it keeps the dirt in place during the spring when we would have water erosion as long as we keep these strips going perpendicular to how the water runs," Dean said.
Strip tilling also increases the efficiency of the nutrients applied on the field, Dean said.
"If we’re no-tilling we’re putting the nutrients on top and letting Mother Nature work the nutrients into the soil, which it will do, eventually. It’s just not quite as efficient as how we do it strip tilling," he said.
And by utilizing GPS and variable rate technology, the Sponheims are able to apply the nutrients that are necessary in certain areas of the field. GPS also helps keep the strips evenly spaced.
Trying new practices
The Sponheims started completing custom work for their customers. And with that, came more experiments on the farm.
In 2008, the Sponheims started experimenting with strip cropping after a customer had asked them about the practice. "I always ask customers if they want me to try something; we do a lot of trial work here," Dean said. "What we found out was it was benefitting us on our bottom line."
By planting eight rows of soybeans and then eight rows of corn right next to each other, Dean found that they were increasing corn yield by 15 to 17 percent. The results are likely due to the fact that there are more "outside" rows of corn.
"Every outside row gets more sunlight, so we’re getting more energy into that corn and producing more bushels," Dean said.
Soybeans, however, lost a little less than 2 percent yield due to shading from the corn plants.
By utilizing the strip cropping pattern, they gained about $100 per acre over the simple cropping system, Dean said. However, he noted, it requires more management and coordination.
Planting isn’t the difficult part because of auto steer, but harvest becomes a little trickier, he said. Also, herbicide and insecticide treatments require a whole field approach, or specialized equipment for corn and soybeans.
The Sponheims found that using larger equipment and planting in 12 or 16 row strips actually decreases the advantages of strip cropping.
"So if you’re trying to scale this up for somebody farming a lot of ground, it gets a little tougher," Josh said. "We don’t have as many outside rows as we do when we narrow that strip."
Likewise, they’ve found that while a 4-row pattern gained another 15 percent in corn yield, they saw a larger yield reduction in their soybean crop.
Cover crop focus
While strip tilling or strip cropping may not be for everyone, Josh said cover crops can help transition from full tillage to strip-till or even no-till.
The Sponheims started using cover crops in the fall of 2012. Now, they grow cereal rye, then clean the seeds and resell them to their customers. "If the crop wasn’t using all the N out there, we wanted something to try to reclaim it, not only from an environmental sake, but because we spent money on that," Dean said.
They’ve planted a variety of cover crops—annual rye grass, tillage radishes, crimson clover—and discovered that cereal rye was best for their farm.
Not only does the cereal rye provide a good cover for their fields, it’s proven to really build soil health.
"The longer we have a living plant growing in the soil, the better we feed the microbes. So when we get a crop that over-winters like cereal rye and starts growing a month before we ever think about putting our cash crop in, it’s another month of something growing we didn’t have before to help that soil continue working the way it should," Josh said.
The Sponheims are constantly looking at the ways they can improve the fields on their century farm. They also know that what works for them might not work for other farmers. But they suggest that farmers get started in conservation by trying one conservation practice.
"Start with something and find what works on your farm," Josh said.
"And ask for advice from others," Dean added. "It would have been quicker for me to fine-tune some practices had I asked for advice or help initially."