Planting Rate

Erv Oelke
Minnesota Extension Service Agronomist
HTML Editors: Jochum Wiersma & Tracy Allrich

To assure planting enough seed, planting rate should be obtained on a seed count basis.

To calculate rate, you need to determine:

  1. Desired population of main stems at harvest.
  2. Average predicted stand loss for your farm.*
  3. Germination value for your seed lot.
  4. Number of seeds per pound of your seed lot.

*It is not uncommon for stand losses of 40% to occur on some fields of soil conditions are poor.

An example for calculating planting rate for wheat:

  1. Desired population is 1,125,000 main stems per acre at harvest.
  2. Historic field stand loss is 10%.
  3. Seed lot germination is 95%.
  4. Seed lot has a seed count of 15,000 seeds/lb.

Then:

  • 15,000 x 0.95 = 14,250 viable seeds per pound.
  • 1,125,000 seeds x 110% = 1,237,500 viable seeds needed per acre.
  • 1,237,000 seeds/14,250 seeds/lb. = 87 pounds per acre seeding rate or 28 total seeds per square foot.

The table below gives a rough estimate of plant count (main stems) needed at harvest for various yield goal levels.

Table 8.

Rough estimate of plant count needed at harvest for HRSW or barley.

Growing Conditions/Yield Goal Level

Plants/Acre at Harvest

Favorable Environments

1.3 million

60 bu/acre and up yields

(30 plants/ft2)

Unfavorable Environments

0.7-1.0 million

15-30 bu/acre yields

(16-23 plants/ft )

Planting Rate and Date

Rates are based on normal seed beds and on normal size, good quality seed. Rates will vary greatly depending on seed cost, desired stand, expected mortality, emerging ability, seed weight, seed germination, seedbed conditions, depth of planting and planting equipment.

Crop

Bushel Weight (pounds)

Seeds/pound (number)

Rate/acre (pounds)

Rate (seeds)

Planting Date

Barley

48

14,300

85

28/square foot

Early Spring

Oat

32

16,200

80

28/square foot

Early Spring

Wheat

Durum

60

12,100

90

25/square foot

Early Spring

Hard Red Spring

60

15,200

80

28/square foot

Early Spring

Winter

60

14,500

75

25/square foot

Aug. 20 to Sept. 20

Replanting Decisions

  1. Assume you wanted a stand of 1,300,000 plants per acre. That requires at least 30 plants per square foot.
  2. Replanting costs must be recovered from a later maturing crop that has a lower yield potential than original crop. Plus, replanting uses extra moisture as a function of soil disturbance.
  3. A) If reduced stand is uniform (no big skips or holes), the keep stands of 15 plants per square foot.
    B) If skips are large (3 to 6 ft.) or holes are 4 to 6 feet in diameter and stand is 18 plants per square foot or less, then replant if moisture is adequate.
    C) After June 1 in northern Minnesota and May 15 in southern Minnesota, a replant decision should be to a crop other than wheat or barley since yields are reduced by about 50% when planting after these dates compared to normal planting dates.



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