April 7, 2000

There has been a lot more talk than experience in Texas when it comes to ultra-narrow row corn, but trials over the last three years in the Blacklands and High Plains should shed some light on the feasibility of the practice for those growers anxious to reduce the per-unit cost of production.

"You can reduce the per-unit cost of production two ways: reduce the crop or increase yield. The latter is the emphasis of ultra-narrow row," said Dr. Thomas Gerik, agronomist at the Blacklands Research Center in Temple.

"It’s being adopted on the High Plains. It’s being adopted in the Midwest, and yield advantages there are not that great—5 to 10 percent. Central, Southwest and South Texas—that’s where I think it really fits well. Anywhere in the South, where temperatures are warmer and evaporation rates are higher, could benefit. Where our yield potentials are lower—100-125 bushels top yield—that’s where we see the greatest benefit."

Evaporation rates are high in Texas—.25 to .50 daily, said Gerik. Of the 2.5 million acres of corn in the Lone Star state, half is irrigated. According to Gerik, irrigated corn typically yields 150 to 200 plus bushels per acre compared to 80 to 100 plus dryland. Mathematically speaking, for every inch of water an acre of corn receives, it produces 9 bushels.

"For every tenth of an inch of water, that’s an extra bushel of corn we’re producing. That’s why we’re interested in ultra-narrow row," the agronomist explained.

One advantage of ultra-narrow row is that the crop forms a more rapid ground cover. Along with lowered soil evaporations, other advantages are cooler soil and plant temperatures; less weed pressure; more water available for the crop; and higher yields.

Beyond having to change cultural practices, a big hurdle for many growers is the cost of equipment conversion.

"The grower has to be in a position to be able to do that, to add row units to the planter, put narrower tires on the tractor that he will use to plant the crops, and a harvester," said Gerik.

The conversion from 40-inch down to 20 requires a new 12-row corn header; new 12-row planter; and narrow-dual tires at an estimated cost of $77,300.

"We based the economics of it on $2.25/bu. corn; a 10-year payout at 10 percent interest; and 15 percent salvage value on equipment," he said. "You need to farm over 300 acres to make it feasible. You would need to farm 600 acres to make it pay to convert from 40-inch to 30."

Studies at the Blackland Center looked at crop/water balance, taking into account factors such as precipitation, irrigation, transpiration, evaporation from soil, drainage, and runoff. Researchers looked at ultra-narrow rows having input on water evaporation.

Objectives of the experiment focused on how much water could be conserved and how much yield increase could be achieved. Another goal was to determine the optimum plant population for the system.

"We have studied this for the last three years here in the Blacklands, in Bell and Williamson counties. Basically 1997, ’98 and ’99. 1997 was a wet year, ’98 was a very dry year, and ’99 was somewhat intermediate at the locations we studied. We got a yield increase under all situations," Gerik reported, suggesting that the ultra-narrow row technique for corn improves the stability of yields in drier years. "You get a bigger boost in yields in a normal year or dry year than a very wet one. Of course, there are not too many wet years in Central Texas, but we do have them. When we have really high rainfall and good conditions, we see an 8 percent yield increase going from 40-inch rows down to 20 inches. Under more normal circumstances, you would see a 15 to 30 percent increase."

Gerik planted an early corn variety, which develops under more favorable conditions in Central Texas, and a medium-late variety for the trials.

"What we were interested in doing was to see if by going to an early variety, and increasing the plant population, we could increase yields. In our studies, we observed the same response in terms of row spacing. In a dry year, the early variety did much better. We didn’t see any advantage to going to the early variety and increasing populations when we had more water, which was a bit of a surprise," he commented.

Most Central Texas growers plant 20,000-22,000 plants per acre. Gerik said if you average the three years of the study—wet and dry—maximum yields were attained at 25,000 plants per acre.

"In a wet year, going up to 30,000 gave us the highest yields. That’s when we had 19 to 20 inches of rain, which is similar to irrigated. We got up to 175 bushels of corn here at Temple on ultra-narrow row plots in 1997. The same year, on dryland we saw a 7 percent yield increase," he said. "But given the fact that ’97 was probably one of those rare years, I’d have to say, year in and year out, we’re not helping ourselves by going above 25,000 plants per acre."

Gerik noted that in 1998, the highest yield was at 25,000 plants per acre (P 3394, a medium-late variety). "We saw a substantial yield increase—31 percent—in Bell County with P 3752 (early variety) and a 25 percent increase in Williamson County, which only received three inches of rain," he said, again emphasizing the benefit of ultra-narrow row in a dry year.

In 1999, increased yields were achieved by increasing plant density in the Blacklands. Gerik’s research team realized a 20 percent yield increase between 40-inch and 20-inch rows in Williamson County.

Sorghum narrow-row studies were conducted at the Blacklands Research Center over an eight-year period in the 1960s and early 1970s.

"They essentially found some of the same results we found with corn—a 20 percent increase in yield when they went from 40 inches down to 20," Gerik reported. "We’ve known that the ultra-narrow row can mean more production. It’s just that up until the last five or six years, we did not have the chemicals in our arsenal, in terms of weed control, to make it work. That was the biggest impediment until recently."

For the last three years, Brent Bean, Extension agronomist in Amarillo, has conducted similar studies in Moore and Deaf Smith counties. Trials there indicate that ultra-narrow row does not provide a notable advantage on irrigated corn.

"We’re pretty much taking the potential water savings out of the equation out here by irrigating," said Bean. "Growers turn the wells on, and they leave them on. They don’t turn them off. They’re also producing very, very high yields—200 bushels plus some years. Under these situations, there is really no advantage to ultra-narrow row. But that’s not to say that there may not be some advantage in terms of water conservation, if growers had to drop off from what they’re putting on now, if they were like the growers around Lubbock who couldn’t fully irrigate," said Bean.

According to Bean, six tests in three years of studies reflected only a 5 to 7 percent increase in yield going from 30-inch to 20-inch to 15-inch rows.

"It was inconsistent. Only one of those years showed a yield advantage. The last year, the 30-inch row corn actually did better than the 20-inch. So if you’re doing it strictly because you think you’ll get a yield advantage, you can’t count on that every year," Bean stated.

Gerik at the Blacklands Center offered this explanation: "One year that I know that he (Bean) didn’t see any differences in yields was probably because the crops under both treatments ran out of fertilizer. If you have other things that are limiting, such as nitrogen, it could mask any response you would see to row spacing."

Bean pointed out some additional pros and cons to ultra-narrow row.

"You probably get better weed control. Another advantage is if you had a late-season hail, the ultra-narrow row allows the corn to canopy back over a bit. There might be a little bit of early season water savings, particularly if we have a hot, dry May. But then there’s some other disadvantages," he said. "The ultra-narrow row is more difficult to scout and more difficult to cultivate. It can be done, but on 15 inches, it becomes almost impossible. There is also more risk to develop some leaf disease problems. So there are trade-offs."

Gerik said grower interest at this stage is hard to ascertain.

"We’ve only been doing this three years. The information is just sort of getting out. We anticipate some interest in looking at these systems’ given crop prices. But I do think—like with all management systems—growers should carefully look at these systems before they change and adopt them because of the investment that’s required.