- The northern Corn Belt has shown the highest and most consistent potential yield increases due to narrow corn row spacing.
- Farmers should realize there is a year-to-year variability in potential yield response to narrow corn rows that may occur due to environmental conditions.
- Proper row spacing allows plants room to explore for nutrients and minimizes the adverse effects of competition from neighboring plants. In Iowa, and in most regions of the Midwest, 20 inches and 30 inches are the most common row spacing configurations.
- At most production sites, 20 inches has been shown to be a better row spacing than 30 inches for corn production.
- Corn product selection and plant population are the most important decisions for any row spacing, including narrow and twin row spacing.
At one time, corn row spacing was determined by the amount of space needed for farm animals to pull equipment between rows. In the 1960s, 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 ongoing 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.
Also, crop yield responses to farm operations can be highly variable and are often impacted by the environmental conditions during the growing season. Farmers should make it a habit of testing new products/concepts on a small scale on their farm to see how they fit in their operation.
PROS OF NARROW CORN SPACING
The potential benefits of narrow row spacing (less than 22.5 inches) can include:
- 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.
- Better weed control. Narrow rows can allow for faster canopy closure and more shading, which can result in better weed control.3
- Less water loss to evaporation. Narrow rows shade the soil surface earlier in the season, keeping soil moist longer.4
- Consolidating farm equipment. Narrow rows can permit farmers to use one planter for multiple crops.
- Higher yield potential. The benefits mentioned above create the potential for yield increases.
CONS OF NARROW CORN SPACING
Potential disadvantages of narrow row spacing can include:
An increased chance of compaction from farm equipment during narrow row planting.1
The possibility that mechanical cultivation and postemergence herbicide applications may be more difficult in narrow rows.3
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
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.
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
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 require less time from emergence to silking. Narrow rows help to reduce plant competition and optimize sunlight interception, which benefits shorter-season corn products.
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
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, Nebraska, a 30-inch twin row spacing and a 36-inch single row spacing both outyielded the 15- and 30-inch single row configurations (Figure 3). A similar nonreplicated, one-year demonstration conducted at the Monsanto Learning Center in Scott, Mississippi, 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 farmers 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.
CORN PRODUCT SELECTION
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 seed representative for more information.
PROS AND CONS OF DIFFERENT CORN ROW SPACINGS
Potential yield increases due to narrow row spacing are higher and more consistent in the northern Corn Belt. Farmers 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.
1Pecinovsky, K.T., Benson, G.O., and Farnham, D.E. 2002. Corn row spacing, plant density, and maturity effects. Iowa State University. Northern Research and Demonstration Farm. Publication No. ISRF02-13.
2Stahl. L., Coulter, J., and Bau, D. 2009. Narrow row corn production in Minnesota. University of Minnesota Extension. Publication No. M1266 2009.
3Nielsen, R.L. 1997. Perspectives on narrow row spacings for corn (less than 30 inches). Purdue University. Publication No. AGRY-96-17.
4Laurer, J. 1996. Planting corn in rows narrower than 30-inches. University of Wisconsin. Agronomy Advice. Publication No. Field Crops 28.423-8
5Gothenburg, NE Learning Center Summary. 2010. Corn row spacing and equidistant planting in 2010. Monsanto Technology Development. The Learning Center at Gothenburg, NE Demonstration Report.
6Scott, MS Learning Center Summary. 2012. Evaluation of three corn row configurations. Monsanto Technology Development. The Learning Center at Scott, MS Demonstration Report. 130922070109