Soybeans

Description

Family

  • Leguminosae
Cover crop of soybeans.
Figure 1. Cover crop of soybeans.

Growth habits

Germination

  • Can be created with leftover or discarded seed.
  • Will germinate quickly in warm, moist soils.
Root systems of soybeans.
Figure 2. Root systems of soybeans.

Top Growth

  • Short height growth.
  • Rapid cover if sown thickly.

Overwintering

  • Killed by frost — do not overwinter.
  • Need catch crop to prevent nitrogen leaching.

Site suitability

  • Wide range of soil conditions.
  • Less tolerant of low pH, droughty and saturated soils.
Soybean root system.
Figure 3. Soybean root system.

Control options

  • Winterkills readily; controlled by tillage and chemical if necessary.

Sensitivity to herbicides

  • See OMAFRA Publication 75 — Guide to Weed Control.

Weed control

  • There are many herbicides registered for use in soybeans but good weed control for a cover crop should not be expensive and may not be needed. Use narrow rows and a high enough plant population to establish a vigorous crop canopy as soon as possible.
  • See OMAFRA Publication 75 — Guide to Weed Control for information on weed control measures.

Benefits and cautions

Nutrient management

  • Will release N and cause leaching in winter and spring.

Pest management

  • Soybean cyst nematode (SCN) is a concern on many Ontario farms. Using a non-resistant variety of soybeans as a cover crop could encourage greater concentrations on farms identified with SCN.

Organic matter

  • Used as forage.
  • Residue readily breaks down.

Getting started

Establishment

  • Planted in fall — but some double crop soybeans after early processing peas — this can become a soybean cover crop depending upon growing conditions.
  • Drill or broadcast seed at a rate of 80 to 100 kg/ha.
  • Germinate quickly in warm soils if planted into moisture.
  • Growth tends to be very short.

Cost and availability

  • Seed is widely available.

Clover (White, Crimson, Berseem)

Description

Family

  • Trifolium spp.
  • Crimson Clover — Trifolium incarnatum.
  • Berseem Clover — Trifolium alexandrinum.

Growth habits

Germination

  • Crimson — hardseeded
    • requires moist conditions
  • Berseem — same as crimson
    • will tolerate a drier seedbed

Top growth

  • Crimson — 30 to 50 cm tall
    • light green foliage covered in soft hairs
    • striking red flower tops the plant
  • Berseem — 30 to 120 cm tall
    • hollow stem, slightly-hairy leaves
    • yellowish white flower

Root system

  • Crimson — simple tap-root, well nodulated.
  • Berseem — short tap root, top 30 cm of root zone.

Overwintering

  • Both are intolerant of extreme cold conditions.
  • Not winter hardy.
  • Will behave inconsistently in regions (extreme southwest or Niagara) where winters are mild.

Site suitability

  • Crimson — Tolerates a wide variety of soil conditions:
    • does not tolerate poor drainage and calcareous conditions
    • has a pH range of 5.0 to 7.0
    • does best on well drained, humified, loamy soils
    • tolerates shade
  • Berseem — Range = loamy and clayey soils:
    • prefers soils with high silt and very fine sand contents
    • tolerates poor drainage and drought better than Crimson
    • has a pH range of 6.5 to 7.5

Control options

  • Mowing + incorporation and chemical control will control clovers.

Sensitivity to herbicides

  • Crimson — controlled by glyphosate; cyanazine or mixes of paraquat with 2,4-D, dicamba and cyanazine.
  • Berseem — controlled by glyphosate.

Weed control

  • Clovers are frequently underseeded into a cereal crop and any weed control measures need to take crop safety of both crops into account.
  • Read product labels carefully to determine if the clover species you prefer is suitable for the herbicide needed for your crop and weed situation.

Benefits and cautions

Nutrient management

  • Ability to supply N not well documented for Ontario, estimates place them similar to red clover.
  • Due to winterkill — could lead to N loss from system in spring.

Pest management

  • Both are attractive to nematodes — particularly root-knot nematodes
  • Provide cover for beneficial insects
  • Berseem — especially attractive to pollinating insects

Organic matter

  • Both have a C:N of @ 10:1

Getting started

Establishment

  • Requires firm, moist seedbed.
  • Can be broadcast or drilled.
  • Seed by six weeks before first killing frost — rate of 18 to 20 lbs/acre Crimson.
  • 9 to 25 lbs/acre Berseem.
  • Should be companion planted with mixtures of: rye, vetches, annual ryegrass and various cereals for winter protection.

Cost and availability

  • Seed is expensive and generally not available in Ontario.