Alfalfa

Alfalfa is one of the most widely grown forage legumes, valued by livestock producers for its high yield and forage quality across multiple cuttings per growing season. It is also an important rotation crop, contributing organic matter and residual soil nitrogen to subsequent crops.

Because a well-managed stand can remain productive for several years, establishment decisions such as variety selection, inoculation, and seedbed preparation have a lasting influence on stand performance.

Family

Fabaceae (legume family)

Genus

Medicago

Principal species

Medicago sativa

Growth habit

Deep-rooted perennial legume forming symbiotic nitrogen-fixing root nodules with rhizobia bacteria

Alfalfa is believed to have originated in the region encompassing present-day Iran and Central Asia, where it was domesticated in antiquity, and it spread along historical trade routes into the Mediterranean, Europe, and eventually worldwide.

Alfalfa is now grown across temperate and semi-arid regions on multiple continents as a major forage crop. Production statistics and regional importance vary and are best obtained from primary sources such as FAOSTAT and national agricultural statistics.

Alfalfa is adapted to a wide range of climates, with dormant and semi-dormant varieties suited to colder regions with pronounced winters, and non-dormant types used in milder or subtropical climates where growth continues over more of the year.

Its deep taproot provides considerable drought tolerance once a stand is established, allowing continued growth under moisture conditions that would stress many shallower-rooted crops.

Alfalfa performs best on deep, well-drained loam soils with near-neutral to slightly alkaline pH. It is notably intolerant of poor drainage and prolonged waterlogging, which favor root and crown diseases and reduce stand persistence.

Alfalfa is seeded into a firm, well-prepared seedbed, and inoculation with the appropriate rhizobia is recommended where alfalfa has not been grown recently, to help ensure effective nitrogen fixation from the outset.

• Variety selection for winter-hardiness/dormancy class matched to the region
• Seed inoculation with compatible rhizobia where needed
• Cutting schedule balancing yield, forage quality, and stand persistence
• Multi-year stand management, since alfalfa is not replanted annually

As a nitrogen-fixing legume, a well-nodulated alfalfa stand typically requires little or no applied nitrogen. However, repeated hay cuttings remove substantial phosphorus and potassium, which generally need to be replenished based on soil testing to sustain yield and stand health.

Alfalfa is grown both rain-fed, where its deep rooting supports reasonable drought tolerance, and under irrigation in arid and semi-arid production regions, where irrigated alfalfa is a major forage crop.

Center-pivot and other pressurized irrigation systems are widely used in irrigated alfalfa production to support consistent yield across multiple cuttings per season.

Root rot, associated with soil-borne pathogens favored by wet, poorly drained conditions, is a major cause of stand decline in alfalfa, while powdery mildew can affect foliage, particularly late in the season. Aphids are significant pests capable of causing direct feeding damage and reducing forage yield, and spider mites can become problematic under hot, dry conditions.

Management combines resistant varieties, attention to drainage at establishment, monitoring, and — where justified — locally authorized control products applied according to their labels.

Alfalfa is typically cut for hay at a bud-to-early-bloom growth stage that balances yield against forage quality, with multiple cuttings taken through the growing season depending on climate and management. Proper curing and drying after cutting are important for preserving forage quality before baling or ensiling.

• Hay and haylage for dairy cattle, beef cattle, and horses
• Pasture and grazing in some production systems
• Pelleted alfalfa products for feed and export markets
• Rotation benefits, including residual soil nitrogen for following crops