Pros and Cons of Different Corn Row Spacings

  • The northern Corn Belt has shown the highest and most consistent potential yield increases due to narrow row spacing.
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  • Growers should realize there is a year-to-year variability in potential yield response to narrow rows that may occur due to environmental conditions.
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  • Corn product selection and plant population are the most important decisions for any row spacing.
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Background

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At one time, row spacing was determined by the amount of space needed for farm animals to pull equipment between rows. In the 1960’s, adoption of narrower rows started when research showed potential corn yield increases in 30-inch rows compared to 38-inch rows.1 Due to the on-going goal of increasing yield potential for an ever growing population, research continues to compare the pros and cons of 30-inch rows to corn rows with more narrow spacing.

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Pros of Narrow Corn Spacing

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The potential benefits of narrow row spacing (< 22.5 inches) can include:

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  • Equidistant in-row plant spacing. In theory, a more equidistant spacing within the row will help minimize competition among plants for water, nutrients, and light.2 Less competition among plants can help when a stress factor is present.
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  • Better weed control. Narrow rows can allow for faster canopy closure and more shading, which can result in better weed control.3
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  • Less water loss to evaporation. Narrow rows shade the soil surface earlier in the season, keeping soil moist longer.4
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  • Consolidating farm equipment. Narrow rows can permit growers to use one planter for multiple crops.
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  • Higher yield potential. The benefits mentioned above create the potential for yield increases​.
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Cons of Narrow Corn Spacing

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Potential disadvantages of narrow row spacing can include:

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  • An increased chance of compaction from farm equipment during narrow row planting.1
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  • The possibility that mechanical cultivation and post-emergence herbicide applications may be more difficult in narrow rows.3
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  • Extra expenses associated with switching to narrow rows, which can include: a new or modified planter, rims and tires, rate increases in insecticide rates and starter fertilizer.3
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Twin Rows

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Figure 1

Figure 1. Corn planted in twin rows should have uniform triangular spacing.

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An alternate option to narrow row spacing is a twin row planting configuration. Twin rows have a 30- or 38-inch center row, which is flanked by twin rows that are 7.5 inches apart and synchronized to have a uniform triangular spacing (Figures 1 and 2). The benefits of twin row spacing are similar to those of the narrow row spacing. For cotton growers, twin row spacing allows corn and soybeans to be planted in twin rows with the same equipment used to plant cotton in a single row formation, with minimal equipment issues.

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Research

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Figure 2

Figure 2. A twin row planting with a 38-inch row center.

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Overall, the northern Corn Belt has shown the highest and most consistent increases in yield potential due to narrow row spacing. Research from the northern states of Minnesota, Wisconsin, and Michigan indicated a 7-10% yield advantage for corn grown in 15- or 20-inch rows compared to a 30- inch row spacing.2,4

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University of Minnesota indicates the more consistent yield increases from narrow rows in the north can be attributed to the shorter growing season and the need for earlier maturing corn products in the north.2 The earlier maturing corn products produce fewer leaves and requires less time from emergence to silking. Narrow rows help to reduce plant competition and optimize sunlight interception which benefits shorter-season corn products.

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Research from the central Corn Belt has shown a lower and more variable potential yield response. Purdue University reported an average yield increase of 2.7% for the 15-inch row spacing compared to 30-inch row spacing in a three year, three location study.3 However, a year-to-year look at the data showed yield increases ranging from -3.1% to +8.2% for the 15-inch row spacing compared to the 30-inch row spacing. Iowa State University reported no yield differences due to narrow row spacing for all locations and corn products in a three-year study. Other research in the central Corn Belt​ has reported yield increases up to 5% due to narrow rows.1,3

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Figure 3

Figure 3. Yield response of corn to 15-, 30-, and 36-inch single row and 30-inch twin row spacings at the Monsanto Learning Center at Gothenburg, NE 2010.

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The Monsanto Learning Centers have conducted demonstrations comparing various single and twin row spacings. In reviewing the three-year average (2008-10) from demonstration plots at the Monsanto Learning Center at Gothenburg, NE, a 30-inch twin row spacing and a single row 36-inch spacing both out yielded the 15- and 30-inch single row configurations (Figure 3). A similar non- replicated, one year demonstration conducted at the Monsanto Learning Center in Scott, MS compared two DEKALB® brand corn products at 30- and 38-inch single row spacings and 38-inch twin row spacings. The study indicated that the 30-inch single rows had the highest yield potential, but growers can increase yield potential with narrow rows if a corn product that is proven to respond to higher plant populations is selected. Similar to the previously mentioned Purdue University study, the contrasting results of these studies suggest the variable nature of yields from year- to-year in different row spacings. However, the most important decisions to make, regardless of row spacing, are those of product selection and planting population.

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Corn Product Selection

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When planting narrow rows and/or higher populations, product selection is essential to help achieve maximum yield potential. Stalk breakage may become more prevalent for some corn products when planted in narrow rows and/or at higher populations. Choose corn products that are rated with a high yield potential when planted in narrow and/or increased populations. Typically, newer corn products are able to withstand higher plant density levels than older corn products. Contact your local area DEKALB® Brands Seed Representative for more information.

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Summary

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Potential yield increases due to narrow row spacing are higher and more consistent in the northern Corn Belt. Growers should recognize the potential year-to-year variability in yield response to narrow rows that can occur in the central Corn Belt and southern regions. Selecting the best product and planting it at the optimal population are the most important decisions for any row spacing. Additional considerations when adopting narrow row spacing are the possibility of: equipment consolidation, cost of new or modified equipment, and changes to management practices.​