Soybean seeding rates
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EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team
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Recent
research conducted in the North Central Corn Belt suggests that soybean
planting populations may be able to be dialed back somewhat without
compromising yield, or more importantly, profitability. Research
conducted throughout the Midwest is showing that a final harvest
population of 100,000 plants per acre is generally sufficient to achieve
maximum yield. The challenge is in deciding what your seeding rate must
be in order to achieve a final harvest population of 100,000 plants or
higher.
What does this mean for Michigan soybean growers? With tighter profit
margins expected for most crops in 2009 including soybeans, growers do
not want to compromise yield. However, as mentioned above, recent
Midwest studies clearly show that it is not necessary to continually
increase soybean planting populations in order to obtain maximum yield.
Unlike corn, soybean has a great propensity to compensate or flex when
plant populations vary. Therefore, the optimal planting population range
is wider for soybean than it is for corn. Determining the minimal scale
of that optimal soybean planting population range will optimize
profitability and still maintain yield. As a starting point, begin with a
planting population of 175,000 seeds per acre for drilled systems and
130,000 seeds per acre for 30-inch rows and then adjust from there based
upon field productivity and planting conditions. Low productivity
fields require higher seeding rates to obtain maximum yield than do high
productivity fields. Similarly, if forced to plant in less than optimal
soil and planting conditions, adjust seeding rates upward to compensate
for expected decreases in seedling emergence and survival.
Several things to consider when operating on the low end of the optimum
planting population range include, managing in a manner that maximizes
emergence and seedling survival. Calibrate your drill or planter to
ensure that seed drop is adequate and uniform across all rows. This is
important to do every year as seed size and planter mechanical
efficiency and wear can vary from year-to-year. Avoid planting when soil
conditions are less than optimal to facilitate good seed to soil
contact and seedling germination. Inoculate soybean seed with Rhizobium
bacteria regardless of field history. Finally, if planting early in the
season, consider using fungicide-treated seed (Be sure it is labeled for
use with your soybean inoculant.) to protect against soil borne root
diseases.
