Take advantage of smaller soybean seed size

Seed size is smaller for many soybean varieties that will be planted in 1996. Reduced moisture availability and above-normal temperatures last Augustthe period of soybean seedfillresulted in smaller seeds in some areas of the state. We have received reports of seed size being 10 to 20 percent smaller than normal for some varieties, with late-planted fields producing the smallest harvested seed in 1995.

Soybean producers should account for smaller seed size when purchasing seed for 1996. A 50-pound bag will go farther this year because seed counts per bag increase with smaller seed size (see attached table). The following example illustrates how seed cost can be reduced without reducing the seeding rate.

A 100-acre field is to be planted to a variety that has a 1996 seed size of 3,000 seeds per pound (compared to 2,500 seeds per pound in a normal year). More seeds per pound means that fewer pounds of seed are needed to maintain the desired seeding rate (see attached table). Using a rate of 175,000 seeds per acre, a producer can save 12 pounds by using the smaller seed (58 pounds versus 70) per acre, or 24 bags over 100 acres (1,200 pounds over 100 acres/50 pounds per bag). If seeds are $16 per bag, the producer saves $384 over 100 acres.

Soybean producers also should account for smaller seed size when calibrating planting equipment this spring. Taking a few minutes to adjust seeding rates can be time well spent in 1996.

Smaller seed size can reduce costs
Pounds per acre = Seeding rate/Seeds per pound
----------------------------------------------------
                            Seeding rate per acre
                         ---------------------------
Seed size  Seeds per
(seeds/#)  50 lb bag      200,000   175,000   150,000
-----------------------------------------------------
  2250      112,500        88.9#      77.8#     66.7#
  2500      125,000        80.0#      70.0#     60.0#
  2750      137,500        72.7#      63.6#     54.6#
  3000      150,000        66.7#      58.3#     50.0#
  3250      162,500        61.5#      53.9#     46.2#
  3500      175,000        57.1#      50.0#     42.9#
  
   # = lb.

This article originally appeared on page 25 of the IC-476 (4) -- April 8, 1996 issue.

Updated 04/07/1996 - 1:00pm