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Competency Area 5: Seeding Rates and Row Spacing

PO 25. Know the recommended seeding depths for major Northeast crops.

Forage crops
Optimum seeding depth for forage crops varies with species, soil type, soil moisture, time of seeding, and firmness of the seedbed. Seed without good seed-soil contact is likely to dry out during the germination process. Seed planted too deep will not have the seed reserves to survive emergence. In humid areas, best results are to seed at a depth of 0.2 to 0.5 inches. Late spring and summer seedings should be sown somewhat deeper due to increased moisture stress.

Established plants from 100 seeds, based on soil type and seeding depth

 

Sand

Clay

Loam

Depth

0.5

1.0

2.0

0.5

1.0

2.0

0.5

1.0

2.0

Species

Established plants,%

Alfalfa

71

73

40

52

48

13

59

55

16

Red Clover

67

66

27

40

35

7

47

45

13

Bromegrass

71

64

29

56

37

6

68

50

19

Orchardgrass

61

56

13

60

26

1

56

39

16

Sund JM, Barrington GP, Scholl JM (1966) Methods and depths of sowing forage grasses and legumes. Proceedings of the 10th International Grassland Congress, 1(56):319-323.

Seeding depth considerations:

Crop response to planting depth
Deep planting delays emergence time and may result in crusting damage to emerging seedlings. Soybeans in particular are susceptible to crusting soil because they have a delicate hypocotyl (the hypocotyl pushes the cotyledons above the ground to develop) that can be prone to breaking as opposed to the coleoptile of grasses. However a deeper seeding depth may enhance emergence because of better moisture, corn in particular.

Crop characteristics

  • (a) Monocots such as corn and small grains have a coleoptile (protective sheath enclosing the shoot tip and embryonic leaves of grasses) which emerges first. They are less vulnerable to problems. The ideal depth for corn is about 1.5-2.0 inches but they can be planted up to 3-inches if it is dry and warm. Planting should be in the 1.5 inch range if done in cool moist conditions.
  • (b) With dicots such as soybeans, the hypocotyl emerges first. The hypocotyl is susceptible to mechanical damage so problems can occur with deep planting. The planting depth for soybean should be from about 1.25 to 2.0 inches. Drilled soybeans are usually planted at the 1.25 inch depth because of depth control issues with the drill whereas soybeans can be planted at the 2- inch depth with a corn planter if it is dry and warm. Planting depth is more crucial with soybeans than corn or wheat because planting at a shallow depth (<1.25 inches) can result in emergence problems if it turns dry, especially under intensive tillage, and planting too deep (>2.0 inches) can result in emergence problems, especially if the soil crusts before emergence.
  • (c) Seed size - smaller seeds (alfalfa) are planted shallower than bigger seed (corn or soybean)

Planting equipment

  • (a) Row crop planters give excellent control of planting depth so you can plant within the recommended depth.
  • (b) Drills may have depth control problems at times which may result in seed that is planted too shallow for conditions.
  • (c) Broadcast seeding of small grains is when the seeds are surface applied and must be harrowed in.

Herbicide placement
Corn or wheat should be planted below the herbicide treated zone.