Seed By Weight, Not Volume

Achieving the right plant population in spring cereals is just as important as corn and soybeans. Less than optimum seeding rates often leads to reduced yields. Over seeding can be costly in extra seed costs. Seeding at 2 or 3 bushels per acre (bu/ac) is just not accurate enough.

Recommended Spring Cereal Plant Populations

The following table is the Recommended Plant Populations for the different Spring Cereal Crops:

Target Plant Population

Crop	Plants/sq.m.	Seeds/acre (x100)
Barley	250 - 350	1000 - 1400
Oats	200 - 300	800 - 1200
Mixed Grain	200 - 350	800 - 1400
Spring Wheat	300 - 400	1200 - 1600

Seeding Rates

To calculate the required seeding rate use this formula:

Seeding Rate (lb/ac) = (Seeds/ac ÷ Seeds/lb) X (100 ÷ % germination)

Seeds per pound (lb) should be given on the seed tag or bag. For instance, if 1.5 million seeds/acre is desired, with a germination rate of 95% and 12,000 seeds/lb, the seeding rate should be 132 lbs/acre.

(1,500,000/12,000 x 100/95) = 132 lbs/ac

Using 2 bu/ac for wheat seeding, a variety with 10,000 seeds/pound will be at a disadvantage to a variety with 13,000 seeds/pound. Two bu/ac (120 lbs/acre) will give an actual seeding rate of only 1.2 million seeds per acre with 10,000 seeds/pound and 1.56 million seeds per acre with 13,000 seeds per pound. In order to seed 1.5 million seeds per acre (recommended rate for most soils other than heavy clays), 150 lbs/acre of the 10,000 seeds/pound variety would be required, while only 115 lbs/acre of the 13,000 seeds/pound variety would be needed!

For example, seeding a spring wheat variety with a small seed size like 606, at 2 bu/ac would be 10% more seed and an additional $3.76 acre in seed costs than seeding at the desired 1.5 million seeds/acre.

The higher range in seeding rates should be used;

1. where emergence and early seedling establishment is likely to be poor ( for example due to poor seed bed and aerial or broadcast seedings), and

for late planting where tillering will be reduced.

Seed Drill Calibration

Calibrating your drill ensures that you are planting at your desired seeding rate. Table 6-8 in OMAF Publication 811 "Agronomy Guide" can be used to indicate the seeds per foot of row, and pounds of seed per acre required needed to achieve various desired plant populations.

Related Links

• Agronomy Guide for Field Crops, OMAFRA Publication 811

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