Tag: planting population

Planting Population Effects on Soybean Yield

Kelly Nichols, Agriculture Agent
University of Maryland Extension, Montgomery County

Research on the effect of soybean planting population on yield was conducted for a second year. In 2019, there were two on-farm locations in Frederick County. This year, the study was expanded to include one on-farm location in Carroll County and four University research farm locations (Keedysville, Beltsville, Upper Marlboro, and Queenstown). Soybeans were planted at 80,000, 100,000, 120,000, 140,000, and 160,000 plants per acre. At the Queenstown location, a population of 50,000 plants per acre was added.

A final stand count was taken prior to harvest at all locations. While we are still summarizing and collecting data, a few observations can be made. Final stand counts indicate that similar plant loss occurred across all planted populations, most likely due to the percent germination of the seed, insects, disease, and weather. Soybeans at the lower populations were more branched and bushy compared to soybeans in the higher populations. This is not surprising, as beans are able to compensate for missing plants around them. This ability to compensate may result in comparable yields across the planted populations. In 2019, yields across all populations were within a few bushels and not statistically different. The cost of the seed will be compared to the sale of the soybeans to determine net profit per acre. For more information on the 2019 and 2020 results (once completed), visit this project’s webpage on the National Soybean Research Checkoff Database.

Effects of Planting Population on Yield in Full Season Soybeans

Kelly Nichols, Agriculture Agent Associate & Matt Morris, Agriculture Agent
University of Maryland Extension, Frederick County

Soybean population plots were planted on two farms in Frederick County near Thurmont and Tuscarora on June 4 and 7, respectively. Planted populations were 80, 100, 120, 140, and 160 thousand plants per acre (ppa). The Thurmont plots were planted on 30-inch spacing with three replications. The Tuscarora plots were drilled on 7.5-inch spacing with four replications.

On July 1, initial population counts were taken at both farms. At the Thurmont farm, plots ranged from 79 to 88 percent germination. At the Tuscarora farm, plots ranged from 88 to 98 percent germination (Table 1). This is consistent with the germination percentage of the seed.

Plots were harvested on October 3 and October 24 at the Tuscarora and Thurmont farms, respectively. The average yield for each farm individually and combined were calculated (Table 2). Yield ranged from 61 to 70 bu/A. Overall, yield differences between the populations were within three bu/A. While a complete statistical analysis has not been conducted, the trend of the data indicates that planting at a lower population, such as 120,000 or 100,000, would allow for reduced seed costs while still maintaining optimum yield.

The variety used at the Thurmont farm was Pioneer P37A69, which retails for $71.00 per unit of 140,000 seeds. The variety used at the Tuscarora farm was Hubner 38-27R2X, which retails for $59.00 per unit of 140,000 seeds. (Note that these costs do not include any discounts or seed treatments.) At the time of harvest, soybeans were $9.51/bu on the Chicago Board. The net dollar amount was calculated by subtracting the seed cost from the gross amount per acre. At the Thurmont farm, the 100,000 planting population had the highest net per acre at $598.19, while the 140,000 and 160,000 populations had the lowest net, around $581/A (Table 2). At the Tuscarora farm, the 120,000 planting population had the highest net per acre at $560.13, while the 160,000 population had the lowest net at $515.76/A.

Planting at lower populations, around 100 to 120 thousand ppa, may not reduce yield or net per acre, indicating that this is a potential for cost savings on farms. We are planning to conduct this study again next year at more locations around the state. To stay up to date with this research project, visit https://go.umd.edu/FCagresearch.

Table 1. Initial Population Counts, July 1.

 

Thurmont Farm

Tuscarora Farm
Planted Population

(1000 plants per acre [ppa])

Initial Population (1000 ppa)

 % Germination Initial Population (1000 ppa)

% Germination
80

63

 79 71

88
100

85

 85 88

88
120

95

 79 117

98
140

123

 88 124

88
160

135

 84 153

96

 

Table 2. Average Yield at 13.5% Moisture and Net Profit in $/A.

 

Yield (bu/A)

Net $/A
Planted Population (1000 plants per acre)

Thurmont Farm

Tuscarora Farm

Both Farms

Thurmont Farm

Tuscarora Farm
80

67

61

64

 596.92

548.18
100

68

 63 65 598.19

554.78
120

69

 64 66 595.33

560.13
140

69

 63 66 581.39

542.89
160

70

 61 65 581.71

515.76