February 1, 2021
Corn Yield Response to Plant Row Spacing and Seeding Rate - 2020
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Corn Yield Response to Plant Row Spacing and Seeding Rate - 2020
TRIAL OBJECTIVE
Row spacing is usually a standardized or fixed practice in most operations. Unlike nitrogen and weed management which can be altered from year to year, most farmers don’t have the luxury of switching row spacing between years. This is partly due to high capital investment in farm equipment.
Proper row spacing allows plants to reach nutrients and avoid 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.
Coupled with seeding rate, row spacing affects canopy closure, weed control, disease development, late-season plant standability, and ultimately yield potential. The objective of this trial was to assess the effects of two row spacings on corn yield potential at three different seeding rates.
RESEARCH SITE DETAILS
Forty-eight corn brands were selected to represent the northern, central, and southern corn growing regions of Iowa. Huxley and Victor locations were lost due to the Derecho, and Marble Rock was lost due to environmental issues, which left us with Atlantic and Storm Lake.
Products were planted at 30,000 (30K); 35,000 (35K); and 40,000 (40K) seeds/acre in both 20-inch and 30-inch row spacings.
Tillage, weed and nitrogen management were the same for all products at the respective locations.
Trials were conducted in 10 ft by 35 ft plots with three replications at Atlantic and two replications at Storm Lake (Figure 1).
UNDERSTANDING THE RESULTS
Figure 1. Effects of row spacing and seeding rate on the average yield of corn products tested. Data represents 48 products from two growing regions in Iowa. The average yield represents the overall average across locations, products, and seeding rates.
Table 1. Summary of corn product performance due to row spacing and seeding rate (‘K’ represents 1,000 seeds/acre).
In this trial, the yield response to seeding rate at each row spacing varied greatly for various products tested.
The 35K seeding rate had a higher average yield for both row spacings but may or may not have a positive return on seed investment.
Overall, 20- and 30-inch row spacings yielded similarly at each seeding rate.
Seeding rate had minimal effect on grain moisture content, but 20-inch row spacing had 1.2% less grain moisture on average across plant densities.
The 20-inch row spacing had a win rate of 52% at the 30K seeding rate. The 30-inch row spacing had a win rate of 52% at 35K; and 54% at 40K seeding rates.
KEY LEARNINGS
In past years, each trial location carried out several row spacing trials in which 20-inch row spacing had consistently out-yielded 30-inch row spacing. However, those trials usually included a limited number of products.
A virtue of adjusting plant configuration, 20-inch is expected to perform better than 30-inch row spacing, especially at higher seeding rates. However, a few products had better average yields at 20-inch compared to 30-inch row spacing at all seeding rates.
Crop yield response to farm operations can be highly variable, and often significantly affected by environmental conditions during the growing season. Growers should test new products and concepts on a small scale to see how it fits in their operation.
Growers should consult trusted agronomists and dealers when selecting the best products for their operation.
February 4, 2020
Corn Yield Response to Row Spacing and Seeding Rate - 2019
TRIAL OBJECTIVE
Row spacing is usually a standardized or fixed practice in most operations. Unlike nitrogen and weed management, which can be altered from year to year, most farmers don’t vary their row spacing between years. This is due, in part, to high capital investment in farm equipment.
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.
Coupled with seeding rate, row spacing impacts canopy closure and weed control, disease development, late-season plant standability, and ultimately yield potential. The objective of this trial was to evaluate the effects of 20- and 30-inch row spacings on corn yield at three different seeding rates.
RESEARCH SITE DETAILS
- Forty-five corn products were chosen to represent the northern, central, and southern corn-growing regions of Iowa. Products were planted at 30,000 (30K), 35,000 (35K), and 40,000 (40K) seeds/acre seeding rates in both 20- and 30-inch row spacings.
Tillage, weed management, and nitrogen management were the same for all products at the respective locations.
The trial was conducted in 10-ft by 30-ft plots with two replications at each location.
UNDERSTANDING THE RESULTS
- There was a wide range of yield responses to seeding rate at each row spacing for the various products (Figure 1).
In general, the average yield increased as the seeding rate increased in both row spacings. However, the two row spacings yielded nearly the same at each seeding rate, with an overall yield difference of just 1 bu/acre between them.
Neither seeding rate nor row spacing had an impact on grain moisture content.
In this trial, 58% of the products yielded higher in 30-inch row spacing than in 20-inch spacing at both the 30K and 35K seeding rates; whereas at the 40K seeding rate, 64% of the products yielded higher in 30-inch spacing than in 20-inch spacing.
KEY LEARNINGS
In the past, each trial location has carried out several row spacing trials in which 20-inch row spacing consistently out-yielded 30-inch row spacing. However, those trials usually consisted of a limited number of products and that may, in part, be the reason for the different outcome of this study year.
By virtue of plant configuration, 20-inches is expected to perform better than 30-inches, especially at higher seeding rates. It should be mentioned that with a few products, 20-inch row spacing out-yielded 30-inch row spacing at all seeding rates.
Crop yield response to farm operations can be highly variable, often impacted by the environmental conditions during the growing season. Growers should make it a habit of testing new products/concepts on a small scale on their farm to see how it fits in their operation.
Growers are also advised to consult their trusted agronomists and dealers in choosing the best products for their operation.
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