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Consider Narrow Rows for Higher Corn Yields in West-Central and Northwest Minnesota

By Jeff Coulter, Extension Corn Agronomist; and Lizabeth Stahl, Extension Educator - Crops

Now is a great time to consider modifications to your corn production system for 2010. A key step to higher corn yields may be narrow rows (narrower than 30 inches). Planting corn in narrow rows increases the within-row distance between plants, which in theory helps minimize competition among plants for water, nutrients, and light. This is particularly true in the northern Corn Belt, where the shorter growing season and cooler air temperatures can limit crop yield potential. For corn growers contemplating narrow rows, consider the following.

Increased Grain Yield

Figure 1. Yield x row width
Figure 1. Average yield for southern Minnesota growers planting corn in 19- to 25-inch rows or 26- to 32-inch rows, as reported in the FINBIN Farm Financial Database. An average of 145 and 1,457 fields were represented in the 19- to 25-inch and 26- to 32-inch row categories, respectively.
Figure 2.jpg
Figure 2. Average yield for west-central Minnesota growers planting corn in 19- to 25-inch rows or 26- to 32-inch rows, as reported in the FINBIN Farm Financial Database. An average of 46 and 180 fields were represented in the 19- to 25-inch and 26- to 32-inch row categories, respectively.
Figure 3.jpg
Figure 3. Average yield for northwest Minnesota growers planting corn in 19- to 25-inch rows or 26- to 32-inch rows, as reported in the FINBIN Farm Financial Database. An average of 33 and 19 fields were represented in the 19- to 25-inch and the 26- to 32-inch row categories, respectively.
The impact of row width on corn grain yield has been variable, but most agree that yield increases due to row widths narrower than 30 inches are greater and more consistent as one moves farther north. Reported yield improvements with narrow rows in the northern, but not in the central or southern regions of the Corn Belt have been attributed to the shorter growing season in the north, which facilitates the need for earlier-maturing hybrids. Earlier maturing hybrids produce fewer leaves and require slightly less time from emergence to silking, resulting in less leaf area available to intercept sunlight when compared to the longer-season hybrids grown in the south.

An analysis of farm financial data generated from growers throughout Minnesota provides an indication of corn performance for narrow rows when compared to 30-inch rows. This information was self reported by growers utilizing farm business management associations with the University of Minnesota and the Minnesota State Colleges and Universities System, and is stored in the FINBIN financial database. When reporting information, growers were asked to select a row width category for each field. Average corn yields for these row width categories are listed below for southern (includes the southwest, south-central, and southeast regions), west-central, and northwest Minnesota (Figures 1-3).

In southern Minnesota, corn grain yield was greater in 19- to 25-inch rows than in 26- to 32-inch rows in two of five years from 2003 to 2007, but was equal for the five-year average (Figure 1). In west-central Minnesota, corn yield was consistently 1 to 8% greater in 19- to 25-inch rows than in 26- to 32-inch rows from 2003 to 2007, resulting in an average advantage of 7 bu/A (Figure 2). From 2003 to 2007, yield in northwest Minnesota was greater in 19- to 25- inch rows than in 26- to 32-inch rows by an average of 18 bu/A. Although these results should be interpreted with caution because they do not represent direct comparisons between row widths, they do indicate that there is a greater potential for yield increase with narrow rows as one moves north.

With generous support from the Minnesota Corn Growers Association, Pioneer, and Monsanto, we will be comparing grain yield and agronomic responses of various hybrids in 20- or 22-inch rows versus 30-inch rows at multiple plant populations at Lamberton, Morris, and Waseca, MN over the next two years, and at Moorhead and Crookston, MN over the next three years.

No Changes in Optimum Plant Population or Hybrid Selection

Many studies have evaluated whether or not plant population should be increased when switching to narrow-row corn. Yield has typically been optimized at a similar plant population regardless of row spacing (Figures 4 and 5). In addition, there is little evidence to indicate that row width should influence decisions regarding hybrid selection. The majority of the research conducted in the northern Corn Belt has found no interaction between row width and hybrid. In other words, hybrids that performed well in 30-inch rows also performed well in narrow rows.
Figure 4.jpg
Figure 4. Corn response to plant population for two row widths. Data are averages over two locations (Lamberton and Waseca, MN) and three years (2005 to 2007).
Figure 5.jpg
Figure 5. Corn response to plant population for two row widths in 2008. Data are averages over four hybrids and two locations (Lamberton and Waseca, MN).

No Change in Grain Moisture at Harvest

Research conducted by the University of Minnesota from 2005 to 2008 in southern Minnesota found that grain moisture at harvest is not significantly influenced by row width (Table 1). In these trials, differences in harvest moisture between 20- and 30-inch rows were never greater than one percentage point.

Table 1. Corn grain moisture at harvest for a population of 32,000 plants/A by row width.
Table 1 JC.jpg

Increased Silage Yield Without a Reduction in Silage Quality

An increase in silage yield has been consistently reported in the northern U.S. for corn grown in 15- or 20-inch rows when compared to 30-inch rows (Table 2). Reported increases in silage yield due to narrow rows have ranged from 4 to 9%. Row width, however, does not influence silage quality or the optimum plant population with regard to silage yield and quality.

Table 2. Response of corn silage yield to row width in various university trials.
Table 2 JC.jpg

Additional Information

A new in-depth fact sheet on narrow-row corn production in Minnesota is now available. Additional information on corn production from the University of Minnesota is available on our corn production website.

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  1. I have been wondering if soybean row spacing affects yield in NW MN. Here (near Oklee) people either plant in 6" rows or plug every other row for a 12" spacing. The wider spacing looks nicer when they come up. Any research on whether or not there is any difference in yield between these 2 ? I am thinking that the more equidistant dispersion of plants with the same per acre population would favor the narrower rows.

  2. Response to Steve
    Seth Naeve, (Soybean Agronomist), here -- In both theory and under research conditions, soybeans planted in an equidistant pattern (all plants are of equal distance from their nearest neighbors (both within 'rows' and across 'rows')). This is nearly impossible to achieve in the field, so approximating this distribution will give one the best chance of maximizing yields. A population of 175K is equidistant spaced at about 6” in all directions. Therefore, if one were to drill with a 6” spacing at 175K you should have soybeans at about 6” intervals.
    Our research in Minnesota indicates that we get a little more than 5% increase in yield potential each time we narrow row spacing 10”. So, 20” rows out-yield 30’s by about 2 ½ bushels per acre. Similarly, 10’s out-yield 20’s by another 2.5 bushels. If one were to extrapolate to 6” rows, one should expect a 3% yield increase when narrowing from 12” rows. This is a pretty small difference, so folks probably wouldn’t notice the yield difference if they plug every other row.
    I agree that the wider rows may look a bit better early in the spring, but there is no real reason to plug every other row. Alternatively, there are a few reasons to consider going to wider rows if a the same time you were to change planters. If one moves from a drill or air seeder to some sort of precision planter in rows there is the potential to either have increased stands or to be able to reduce seeding rates a bit due to better emergence, thus saving enough in input costs to cover any potential reduction in yield.
    Seth Naeve
    Soybean Agronomist, University of Minnesota


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