One thing long-time no-tiller Roy Pfaltzgraff likes to do at his research farm and education center is challenge other farmers to question their practices when it’s necessary.

Row spacing is a prime example: Oftentimes major manufacturers “tell us what we’re going to do,” he says, but growers are responsible for determining what works best on their own farm. While variables like location and soil condition play a part in determining row spacing, a shift toward narrower rows has occurred in recent years — from 36-inch rows down to 15-inch rows in some cases. 

To better understand the reasoning behind the narrow spacing and its possible effects, the fourth-generation Colorado grower closely examined the key elements of this strategy. 

A Question of Numbers

One of the first crops Pfaltzgraff recalls experimenting with on row spacings was drilling sunflowers, a crop his family has been raising since the 1970s. 

“If you don’t know anything about sunflowers, they have tremendous root systems. There’s research that shows sunflowers can go down 20 feet and they’ll cycle micronutrients up into the root zone,” Pfaltzgraff says. “We’ve always found our best crops follow sunflowers as long as we control evaporation.”

In early row-spacing experiments, Pfaltzgraff drilled the same population of sunflowers that he would have planted, about 14,000 plants. Although the seeds germinated, the resultant stand was fragmented and Pfaltzgraff recalls being able to walk across the field without touching a plant. 

The following year, he increased to 18,000 plants per acre with improved results. But the third year, thanks to a mistake made while setting up his seeder, he had a good stand. The stand consisted of a staggering 40,000 plants and produced 100 bushels per acre.

With an average annual rainfall of just 14 inches, moisture is a limiting factor for PFZ Farms. But Pfaltzgraff believes the best way to conserve water is to run it through a plant. 

“If I have a canopy, the canopy will hold that moisture, it’ll create that microclimate.” However, the benefits of a full canopy extend beyond moisture retention. In Colorado, sustained wind speeds of 40 mph aren’t uncommon. “That’s hard on plants,” Pfaltzgraff says. 

A closed canopy also allows plants to support each other against wind in addition to retaining moisture. The canopy will also retain CO2, making the plants more efficient with their photosynthesis.

Row Spacing and Seeding Rates

In Colorado, however, canopies rarely cover the soil. Pfaltzgraff says he can drive along a conventionally planted cornfield and get a clear sightline down each row. This prompted him to experiment with 12-inch row spacing, which created 8 miles of furrows per acre compared to only 3 miles with 30-inch planter spacing. 

“I’m still planting an acre, but I’m interacting with a lot more of that acre,” he says. 

As with the sunflowers, Pfaltzgraff quickly realized that running the same seed rate per acre resulted in gaps. Some rows wouldn’t have any seed at all. In this case, Pfaltzgraff realized, an even stand depended on multiplying the seed population by 2.67, in keeping with the 8:3 furrow ratio. “If you change the width of the row, you have to change your population to fill that row,” Pfaltzgraff says. 

SEEING THE DIFFERENCE. These images depict ground cover differences between traditional 30-inch row spacing and narrower 12-inch spacing. The seeding rate remains constant in both scenarios, even with an increased total furrow length. The result is uneven ground cover that would predispose the soil to drying and erosion. Courtesy of Roy Pfaltzgraff

Adjusting the rate, however, doesn’t guarantee a uniform stand. Pfaltzgraff’s seeder is equipped with GPS to ensure rows are straight. It requires temperature-based fan adjustments. And, even with a custom distribution system to ease the way, Pfaltzgraff admits his rows will never be perfect. But they’ll be close. 

Although he was still putting a plant every 13.5 inches, with 12-inch row spacing, Pfaltzgraff was closing the canopy and retaining water. Moreover, individual root systems were now engaging with each other. “I’m now interacting with 100% of my soil in every acre,” Pfaltzgraff explains. In Colorado, 30-inch rows starve microbes of root exudates. “They have no reason to work.” 

In addition to offering stability, a closed canopy means the plants are maximizing their light absorption, making full use of nutrients, holding as much moisture as possible, and reducing erosion. “I’m optimizing what I have,” Pfaltzgraff says. 

Identifying Goals is Key

Farming isn’t a one-size-fits-all industry, but Pfaltzgraff highlights a key consideration. “Sometimes we get hung up on a practice and we don’t look into why the practice is so important. Producers will say, ‘We’re too dry to do this.’ Are you too dry or too wet to do the practice? Or are you too dry or too wet to do the idea? What’s the principle behind it?”

Pfaltzgraff uses his farm to illustrate. By conducting his research, Pfaltzgraff has found his operation too dry to support cover crops. Scientific studies validate his findings. “I’m too dry to do cover crops like they do in Iowa,” Pfaltzgraff says. “But I’m not too dry to have diversity in my operation to give the same soil benefits that the cover crops are intended to provide.”

BETTER COVERAGE. The image on the left shows 30-inch row spacing with standard seeding rate. The picture on the right shows narrower 12-inch row spacing with adjusted seeding rate for longer furrow length. Note the extensive ground coverage. Courtesy of Roy Pfaltzgraff

What if he were farming in Iowa? In Iowa, he says, some producers use 60-inch rows to mitigate crop disease concerns. They’re planting 60-inch corn with cover in between. Different practices, true, but the effect is almost identical to Pfaltzgraff’s narrow-row corn in Colorado, with both systems operating at maximum efficiency.

Pfaltzgraff encourages producers to customize their strategy to suit their farm’s specific needs and objectives. “We’re achieving the same goal, but we’re taking a different route to get there. We must ask, ‘What is our goal?’”