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Extension > Agriculture > Crops > Corn Production >Planting > Narrow-row corn production in Minneosta

Narrow-row corn production in Minnesota

Lizabeth Stahl, Extension Educator – Crops; Jeff Coulter, Assistant Professor and Extension Corn Agronomist; and David Bau, Extension Educator – Farm Business Management

Copyright © 2009 Regents of the University of Minnesota. All rights reserved.

SUMMARY

BACKGROUND

With narrow profit margins, it is necessary for corn growers to utilize production practices that increase yield and reduce variable performance across environments. This is particularly true in the northern Corn Belt, where the shorter growing season and cooler air temperatures limit crop yield potential. One possible way to increase yield and reduce variability in yield is through the use of narrow rows.

According to field surveys conducted by the USDA National Agricultural Statistics Service (2008), the average row width for grain corn in Minnesota in 2008 was 28.7 inches, with 3.8% of the acreage in row widths narrower than 20.5 inches. Although the majority of corn in Minnesota is planted in 30-inch rows, these results indicate that a significant number of acres are planted in narrow rows (less than 30 inches wide). In comparison, the average row width for grain corn was estimated as 30.5 inches for Iowa and Wisconsin, and 31.6 inches for Nebraska.

Recent interest in narrow-row corn (typically in row widths of 22, 20, or 15 inches), has been driven in part by the desire to use one planter across more than one crop. A 22-inch row width, for example, allows sugarbeet growers to use the same planting equipment for sugarbeet, corn and soybean. Twin-row corn, where corn is planted in row pairs 6 to 8 inches apart with 30 inches between the centers of row pairs, is a variation of narrow-row corn that will be discussed separately in this article. Planting corn in rows narrower than 20 inches is rare, due in part to difficulty with postemergence herbicide applications and harvest.

Much of the narrow-row corn production research in the Corn Belt was conducted in the 1990s or earlier, prior to the availability of transgenic hybrids with resistance to herbicides and insects. Corn plant populations have also increased over time, emphasizing the need to revisit the effects of row width on corn production and economic return.

AGRONOMIC CONSIDERATIONS FOR NARROW ROWS

Increased grain yield

Planting corn in narrow rows results in a more equidistant spacing of plants, which in theory helps minimize competition among plants for water, nutrients and light. In the presence of a significant yield-limiting factor, the likelihood of a yield increase for growing corn in narrow rows is expected to be greater.

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 (Lee, 2006). 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.

Research conducted in Minnesota illustrates the potential for a yield increase when corn is planted in narrow rows, although results have not always been consistent. In one set of trials, corn yield was 7 to 8% greater in 20-inch rows than in 30-inch rows when averaged over three years at each of three locations (Table 1). A yield advantage was not seen, however, in trials conducted from 2005 to 2007 at Lamberton and Waseca, MN (Figure 1). In experiments conducted at Lamberton and Waseca in 2008, yield was 9% greater in 20-inch rows than in 30-inch rows, and this was consistent across the four hybrids and six plant populations used at both locations (Figure 2).

Table 1. Corn response to row width in Minnesota. Data are averages of three hybrids and four populations (25,000 to 40,000 plants per acre) at each location. Source: Porter et al. (1997).

Yield increase with 20-ich vs. 30-inch rows Yield with 20-inch vs. 30-inch rows
Location 1992 1993 1994 3-yr average 3-yr average
  ----------&---------- ---bu/A---
Lamberton, MN 7 15 5 7 136 vs. 106
Morris, MN 7 -2 11 8 114 vs. 106
Waseca, MN 10 10 4 8 157 vs. 146

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. From 2005 to 2008 at Lamberton and Waseca, MN, corn response to plant population was similar for both 20- and 30-inch rows (Figures 1 and 2).

Figure 1. 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). Source: Coulter (2009).

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 spacing and hybrid. In other words, hybrids that performed well in 30-inch rows also performed well in narrow rows.

Figure 2. Corn response to plant population for two row widths in 2008. Data
are averages over four hybrids two locations (Lamberton and Waseca, MN).
Source: Coulter (2009).

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 2). In these trials, differences in harvest moisture between 20- and 30-inch rows were never greater than one percentage point.

Table 2. Corn grain moisture at harvest for a population of 32,000 plants/A by row width

  Lamberton, MN Waseca, MN
Year 20-inch 30-inch 20-inch 30-inch
------------------------------------%-----------------------------------
2005 17.0 17.1 16.0 15.4
2006 14.2 14.4 17.2 16.2
2007 14.5 14.4 14.5 14.6
2008* 15.5 16.7 16.8 17.3
4-yr avg. 15.3 15.7 16.1 15.9
*Data from 2008 are averaged over four hybrids.

Increased silage yield without a reduction in silage quality

An increase in silage yield has been consistently reported in the northern United States for corn grown in 15- or 20-inch rows when compared to 30-inch rows. Reported increases in silage yield due to narrow rows have ranged from 4 to 9% (Table 3). Row width, however, does not influence silage quality or the optimum plant population with regard to silage yield and quality.

Table 3. Response of corn silage yield to row width in various university trials.

Location Site-years evaluated Row widths compared (inches) Increase in silage yield with narrow rows (5) Source
Michigan 2 15 vs. 30 5 Widdicombe and Thelen, 2002
New York 3 15 vs. 30 4 Cox et al., 1998
New York 2 15 vs. 30 7 Cox and Cherney, 2001
New York 9 15 vs. 30 4 Cox and Cherney, 2002
New York 2 15 vs. 30 7 Cox et al., 2006
Pennsylvania 10 15 vs. 30 9 Roth, 1997
Wisconsin 12 15 or 20 vs. 30 7 Rankin, 2000

Improved weed control

The majority of research in soybean has shown that narrow rows lead to quicker canopy closure, a reduction in the quantity of light that reaches the soil surface, and a reduction in weed emergence later in the season. As a result, narrow rows can enhance weed control in soybean, particularly since glyphosate, the leading herbicide used in soybean, has no residual activity.

Results from weed management studies in narrow-row corn, however, have been less conclusive. A review of research from across the United States by Bradley (2006) found that narrow row widths provided better late-season weed control than 30-inch rows only 24% of the time (12 of 50 site-years). In the research reviewed, differences in light penetration through the crop canopy between narrow-row and 30-inch rows were not always evident, and appeared to diminish as the season progressed.

A disadvantage historically cited for narrow-row corn is the difficulty or inability to perform row cultivation after crop emergence. Growers have shifted away from row cultivation as a weed control tactic in recent years, but if the incidence of weeds that are difficult to control or resistant to glyphosate increases, this practice may increase in popularity. If cultivation in corn is desired, a narrow-row production system could be problematic.

Cost considerations for narrow-row corn

Farm financial results by row width

An analysis of farm financial data generated from growers throughout Minnesota provides an indication of corn performance and machinery costs 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 FINBIN , the financial database developed by the Center for Farm Financial Management (2009). When reporting information, growers were asked to select a row width category for each field. Results generated by FINBIN for the 19- to 25-inch and 26- to 32-inch row width categories are reported below for southern (includes the southwest, south-central, and southeast regions), west-central, and northwest Minnesota, representing 33, 16, and 15 counties, respectively.

Individual grower information is strictly protected and unavailable through FINBIN, and a minimum number of farms fitting the categorical criteria must be met for a report to be generated. It is also important to note that the number of farms within each row width category is not equal and that participants were not exactly the same over years. This information, however, provides a reliable snapshot of how narrow-row systems have performed for producers across the state, along with the associated machinery costs when compared to 30-inch rows.

Average machinery costs per acre were available for 2005 to 2007 and are reported in Table 4. In two of three years in southern and west-central Minnesota, the 19- to 25-inch group reported lower machinery costs per acre than the 26- to 32-inch group, with differences ranging from $0.75 to $12.02 per acre. In northwest Minnesota, the opposite occurred, with reported machinery costs being lower for the 26- to 32-inch group in two of three years. When compared to the 26- to 32-inch group, machinery cost per acre averaged over three years for the 19- to 25-inch group was lower in southern and west-central Minnesota and slightly higher in northwest Minnesota. Factors such as equipment age, how long equipment had been held, and whether equipment was shared across other crops in the rotation are unknown, and likely contributed to the observed differences.

Table 4. Average machinery costs reported by corn growers in the FINBIN Farm Financial Database for 19- to 25-inch rows and 26- to 32-inch rows in Minnesota*.

Southern MN West-central MN Northwest MN
Year 19-25 inch 26-32 inch 19-25 inch 26-32 inch 19-25 inch 26-32 inch
  ----------------------------------------$/A----------------------------------------
2005 85.17 79.94 77.76 77.01 71.53 87.00
2006 81.52 85.48 75.48 79.71 99.26 88.56
2007 89.73 96.91 80.39 92.41 89.96 83.18
3-yr avg 85.47 87.44 77.88 83.04 86.92 86.25

* Machinery costs reported are the sum of fuel, oil, repairs, custom hire expense, machinery lease payments, machinery depreciation, and interest on intermediate debt divided by acres.

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 3). 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 4). In northwest Minnesota, yield was never lower in 19- to 25-inch rows when compared to 26- to 32-inch rows, with an advantage to narrow rows occurring in 4 of 5 years (Figure 5). 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 are not direct comparisons between row widths, they do indicate that there is a greater potential for yield increase with narrow rows as one moves north.

Figure 3. 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 4. 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 5. 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 26- to 32-inch row categories, respectively.

Twin-row corn

Twin-row corn, where corn is planted in row pairs 6 to 8 inches apart with 30 inches between the centers of row pairs, is a variation of narrow-row corn. To date, there has been little research in Minnesota comparing corn grown in twin-rows and 30-inch rows. Growers that have adopted this practice report increased yields, enhanced weed control due to faster canopy closure, and stronger stalks. If a twin-row configuration enhances performance of other crops in the rotation, overall profitability of this row configuration could be enhanced. Further research is needed to determine the agronomic effects and cost effectiveness of this practice in Minnesota.

One advantage of twin-rows over 20- to 22-inch rows is that one can use a standard 30-inch combine head to harvest twin rows. Other costs, such as starter fertilizer and soil insecticide applied at planting, would likely be greater for a twin-row configuration when compared to 30-inch rows, as seen with the more conventional narrow-row situations.

Figure 6. Twin-row corn planted in a 22-/8-inch row width configuration.

CONCLUSIONS

Direct comparisons in southern and central Minnesota indicate that producing corn in narrow rows can increase grain yield by up to 7 to 9%, although yield increases have not always occurred. Analysis of farm financial records from growers across key corn producing areas of the state indicate that average yields were greater in 19- to 25-inch rows than in 26- to 32-inch rows in west-central and northwest Minnesota, while results were inconsistent in southern Minnesota. This supports the trend of a yield advantage to narrow rows being more likely as one moves north. Analysis of farm financial records also reveals that average machinery costs were virtually equal or less for growers planting corn in 19- to 25-inch rows when compared to 26- to 32-inch rows.

References

Bradley, K.W.  2006. A review of the effects of row spacing on weed management in corn and soybean. Crop Management doi:10.1094/CM-2006-0227-02-RV.

Center for Farm Financial Management. 2009. FINBIN Farm Financial Database [Online]. Available at http://www.finbin.umn.edu/default.aspx (verified 1 June 2009). Univ. of Minnesota, St. Paul.

Coulter, J.A. 2009. Optimum plant population for corn in Minnesota [Online]. Available at http://www.extension.umn.edu/distribution/cropsystems/M1244.html (verified 1 June 2009). Univ. of Minnesota, St. Paul.

Cox, W.J., J.J. Hanchar, W.A. Knoblauch, and J.H. Cherney. 2006. Growth, yield, quality, and economics of corn silage under different row spacings. Agron. J. 98:163-167.

Cox, W.J., and D.J.R. Cherney. 2002. Evaluation of narrow-row corn forage in field-scale studies. Agron. J. 94:321-325.

Cox, W.J. and D.J.R. Cherney. 2001. Row spacing, plant density, and nitrogen effects on corn silage. Agron. J. 93:597-602.

Cox, W.J., D.R. Cherney, and J.J. Hanchar. 1998. Row spacing, hybrid, and plant density effects on corn silage yield and quality. J. Prod. Agric. 11:128-134.

Lee, C.D. 2006. Reducing row widths to increase yield: Why it does not always work. Online. Crop Management doi:10.1094/CM-2006-0227-04-RV.

Porter, P.M., D.R. Hicks, W.E. Lueschen, J.H. Ford, D.D. Warnes, and T.R. Hoverstad. 1997. Corn response to row width and plant population in the northern Corn Belt. J. Prod. Agric. 10:293-300.

Rankin, M. 2000. Narrow row corn silage update [Online]. Available at http://www.uwex.edu/ces/crops/NarRow2000.htm (verified 1 June 2009). Univ. of Wisconsin, Madison.

Roth, G.W. 1997. Potential of narrow row corn production in Pennsylvania. Agronomy Facts 52. Pennsylvania State Univ., Univ. Park.

USDA-NASS. 2008. Agri-View, Issue AV-21-08 [Online]. Available at http://www.nass.usda.gov/Statistics_by_State/Minnesota/Publications/Agri-View/agvw2108.pdf (verified 1 June 2009). Minnesota Dep. of Agriculture, St. Paul.

Widdicombe, W.D., and K.D. Thelen. 2002. Row width and plant density effect on corn forage hybrids. Agron. J. 94:326-330.

Thanks to the Minnesota Corn Growers Association and the Minnesota Corn Research and Promotion Council for their generous support of University of Minnesota corn production research. Thanks also to Tom Hoverstad and Steve Quiring for conducting much of the research summarized in this publication and to Jim Kurtz for reviewing this publication.

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