Figure 1 - Lush green alfalfa

Figure 2 - Root systems for alfalfa plants

Family:

• Leguminosae
• Species Medicago sativa L.
• Herbaceous perennial legume not commonly used as an annual cover crop
• Some annual varieties available

Growth Habits

Germination

• Inoculation needed if alfalfa not regularly grown
• Slow to establish

Top Growth

• 5 to 25 stems per crown
• Growth of 40-60 cm in height

Root System

• Tap root
• Nitrogen fixing nodules on main tap and lateral roots

Overwintering

• Perennial varieties go dormant over winter and generally survive well unless heaving, waterlogging or icing occurs
• Cutting or mowing during the "critical fall harvest period" increases the risk of winter injury or winterkill with perennial varieties
• Annual varieties continue to grow all fall and will usually winterkill

Site suitability

• Performs best on a deep permeable soil – adequate soil moisture but no prolonged periods of standing water
• Not tolerant of severely compacted soils
• Intolerant of acidic soils (pH < 6.2)

Control Options

• Tillage
• Herbicides

Weed Control

1. safe to the cereal crop
2. effective on the weeds
3. safe to the cover crop

Sensitivity to Herbicides

Benefits and Cautions

Nutrient Management

• Requires high P and K levels

Pest Management

• Provides a break in crop rotation
• Host to slugs – a problem for subsequent reduced till crops

Organic Matter

• Large biomass producer
• Breaks-up some compacted layers

Erosion Control

• Excellent cover once established
• Improves soil infiltration and permeability

Getting Started

Establishment

• 13 kg/ha seeding rate
• Firm seedbed, no till seeding works with care
• Shallow seeding depth
• Requires adequate seedbed moisture – spring preferred; August seeding is more inconsistent

Cost & Availability

• Expensive seed, particularly as a single season cover crop
• Perennial seed – widely available
• Seed for annual varieties – less available