Revisiting Corn Row Width and Population

Michigan researchers re-evaluated the effects of higher populations and narrow rows on the yield of some newer corn varieties developed for the Northern Belt. Their findings were published in the report "Row Width and Plant Density Effects on Corn Grain Production in the Northern Corn Belt", William C. Widdicombe and Kurt D. Thelen, Michigan State Univ., Agronomy Journal 94:1020-1023 (2002).

During 1998 and 1999, the researchers conducted an investigation that included six different corn hybrids planted in six different Michigan locations that included maturity ranging from 93 to 108 days; ear types that included determinate, indeterminate, and flex; leaf orientation that ranged from wide to upright; and height ranging from medium-short to tall.

They found that narrower rows and higher populations improved yields as seen in the following tables.

Table 1. Effect of row width (average across all variable, dates, and locations)

Row width (inches)

Yield (bushel/Ac)

% Moisture

% Lodging

30

177.5

19.6

1.60

22

181.0

19.2

1.92

15

184.2

19.2

1.65

Table 2. Effect of Plant Density (average across all variables, dates, and locations)

Plant Density (plants/ac)

Yield (bushel/ac)

% Moisture

Test Weight (lbs/bu)

% Stalk Lodging

22,672

168.0

19.7

57.5

2.15

26,316

177.4

19.5

57.6

2.22

29,555

181.5

19.4

57.7

2.21

32,794

184.3

19.3

57.7

2.40

36,437

186.3

19.2

57.7

2.67

Their conclusions were as follows... "Average corn grain yield increased 2 and 4% when row width was narrowed from 76 cm (30 in) to 56 and 38 cm (22 and 15 in respectively) over the 2 yr. and 11 locations of this study. Corn grain harvest moisture decreased by a factor of 2.1 when row width was narrowed similarly. The decrease in grain moisture at harvest was small but statistically significant over the scope of the study and suggests a modest potential savings in grain drying costs with narrow row corn systems. Plant density affected grain yield, moisture, test weight, and stalk lodging. The highest plant density evaluated, 90,000 plants ha-1 (36,437 plants/a), had the highest grain yield. A plant density x hybrid interaction was observed. Grain moisture decreased for early maturing hybrids as plant density increased, but moisture levels were consistently high across all plant density levels for the later maturing hybrids. A hybrid x row width interaction was not observed, indicating hybrids that yield well in conventional 76 cm (30 in) row systems will also yield well in narrow row systems. Similarly, a plant density x row width interaction was not observed, which suggests the increased yield effect observed with narrow row systems will generally occur across the range of plant densities commonly used by growers in the northern Corn Belt."