Soybean Planting Population Trial We chose to adapt the soybean planting population trial that was conducted by the High Plains FFA chapter in 2021 to the Orthman research farm in 2022. It has been standard practice to plant high populations of soybeans in order to overcome crusting, emergence issues, and potential insect damage. This has been the thought process because soybean seed has generally been inexpensive. From the agronomic standpoint this thought process causes plants to be overcrowded and cause inter plant competition and can result in unnecessary expenses. The purpose of this trial is to help define what the optimum planting population for soybeans planted in 30” rows. Soybean Planting Population Results and Discussion Sixteen rows of soybeans were planted a length of 1232’ at populations of 150,000, 120,000, 100,000, 80,000, and 60,000 seeds per acre. Because of weather conditions and heavy rain, emergence was poor and very erratic across the west 2/3 of the research farm. This led to replanting at a population that was 30 percent less than the original planted population. Because the planting population trial was also in this area of the research farm it was replanted at the following populations 105,000, 84,000, 70,000, 56,000, 42,000 directly planted over the existing row. Continued erratic weather resulted in final stand across the entire research farm of 72% of dropped population regardless of replanting or not. The planting population trial ranged from 50.6 to 70.5 percent of target population, planting population and final stand counts are listed in Figure 8. This was a difficult trial in 2022 where soybean emergence was difficult and resulted in erratic plant spacing however, we feel that there are still lessons to learn from this trial.
Percent of Target
150,000 120,000 100,000 80,000 60,000
105,000 84,000 70,000 56,000 42,000
100,125 84,625 64,000 43,750 30,375
66.8% 70.5% 64.0% 54.7% 50.6%
Figure 8. Planting population and final stand count for soybean planting population trial. The purpose of the broad range of planting populations in this trial are not to recommend anyone to see how low of population that they can plant but rather to help define a better planting population that could result in a better ROI for the grower. Lowered planting populations in soybeans needs to be managed and understood before diving in whole hog.
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