Southeast Missouri farmer John Engram didn't consider himself a twin-row corn producer when he first started experimenting with it in 1993. Instead, he was trying to find the optimum row spacing for ultra-narrow-row corn on beds.
Engram, speaking at the National Conservation Systems Cotton and Rice Conference in Tunica, Miss., was encouraged by yield increases seen by Midwest producers moving from 30-inch rows to 20-inch rows and even narrower. “I was excited about that, but since I was a ridge-tiller, I didn't want to give up my beds. I liked not having to do a lot of tillage in the spring. So I wanted to see if there was a way to make UNR corn work and still keep my beds. So in 1993, I wasn't doing twin-row corn, I was experimenting with UNR on beds.”
The experiment paid off with higher yields, and Engram expanded the twin-row concept to more corn acres as well as to cotton, soybeans and milo.
After cotton, going into twin-row corn, Engram cuts stalks from the preceding fall, then plants twin-row corn 7.5 inches apart on top of the old twin-row cotton stalks. Rows are on 38-inch spacing and are plenty wide for the two rows.
“We give the corn a double shot of nitrogen using a rolling coulter run between the two 7.5-inch rows. We put out 25-30 pounds of actual nitrogen in a 28-0-0-4 solution, so we have our sulfur right there available, too. The thing I like about having a starter shot of nitrogen between the rows is that we have a lot of rain in southeast Missouri, which does tend to leach out the nitrogen. On beds, water tends to run off into the middles minimizing any leaching. We have seen some really good growth responses and yield responses from having the starter fertilizer out there.
“Later we'll come back with another shot of nitrogen, urea with Agrotain, using a variable-rate spinner buggy. That gives us a good 10-14 days without volatilization until we can get some rain. We'll also put out nitrogen probes in the spring to see how much might still be available from the crop before.”
Engram's Monosem planter plants the twin-rows in a diamond-shaped pattern to maximize spacing between plants. “The nice thing about getting your root systems away from each other is that they have a little more room to grow. It also gives you a better root mass, which makes your ears more uniform in size.”
Engram says the trick to twin-row planting is to increase plant population without sacrificing stalk strength. “With a single row of corn plants, we need a high population to push yields over 200 bushels. But we don't want to lose our standability. That's one reason why I tried the twin-row system. I wanted to increase my plant populations while increasing the space between plants at the same time.
The reason for increased yield with twin-row corn is simple mathematics, according to Engram. “If you can plant 38,000 plants and get ears that are the same size as if you planted 32,000 plants, you harvest 6,000 more ears. If you have more kernels out there at harvest, you'll make more yield.”
Twin-row producers may make fewer weed control applications and water less during dry periods, according to Engram. “The canopy is so thick with twin-row that it not only keeps the crop from developing weeds later, but it also helps you conserve water. I grew single-row corn and twin-row corn at the same time, and you'd be surprised at how much water there is in the twin-row corn versus the single-row corn. The sun is a very powerful force. It will eliminate a lot of your water.”
Engram says twin row is about 2 days earlier than single-row corn.
Twin-row corn is harvested the same way as single-row corn. While there is a noticeable shake as two rows of corn enter the combine header, Engram hasn't noticed any other adverse effects. “We had the University of Missouri come out to evaluate the system, and we actually had less harvest loss in twin-row than we did in single-row. We think a lot of that is because the corn plants have to follow each other so quickly into the header they don't have time to bang into each other.”
Harvest of twin-row cotton with in-line heads, “can be a problem,” Engram added. “Our research has shown us that at 7.5 inches, you're still fine, but if you get much wider than 8 inches, you're going to get a lot of tagging.”
Engram has planted corn at 46,000 plants per acre with no standability issues. “I wouldn't recommend you do that. We've done a lot of yield and population studies and the sweet spot is 36,000 to 38,000 final population on irrigated soils, dropping down to 32,000 plants on dryland soils.”