1. Good Drought Tolerance

• Lucerne is drought tolerant due to its water use efficiency (WUE). WUE is the ratio of total dry matter accumulation to total water input (kgDM/ha/mm of water used).
• Drought tolerance is influenced by soil depth, soil texture, plant species and rooting depth.
• Lucerne has a taproot which can extract more available water from the soil profile than some grass species.
• WUE is highest in spring.
• Species with high herbage nitrogen (N) content have high WUE. Lucerne has a higher herbage N content than most grass/clover pastures and therefore a higher WUE.

2. Nitrogen Fixation

• Lucerne is a legume that can fix its own nitrogen, (i.e. convert atmospheric nitrogen into plant available nitrogen) reducing the requirement for application of nitrogen fertiliser.
• Nitrogen fixation is directly proportional to herbage grown (lucerne produces approximately 25kg N/t of above ground DM/ha).
• Lucerne will fix more N annually than white clover pastures due to higher yield when soil moisture is limiting.
• Lucerne does not require nitrogen application once established. Applying N may decrease N fixation and encourage growth of weeds within the stand.

3. Longevity

• Typically, lucerne persists for 4-8 years in a pastoral system (stands can persist longer in drier environments where pressure from weeds is low and well controlled).
• Persistence is dependent on grazing management and pest and disease pressure.
• Stand renewal is based on a decline in plant population and an invasion of taprooted and rhizomatous weeds, for example dandelion, yarrow and couch/twitch.

4. Increased Dry Matter Production

• In a dryland environment, lucerne can produce up to 40% more dry matter than other pasture species
• Lucerne produced the highest annual yield compared with ryegrass/white clover pastures in an eight year dryland experiment at Lincoln University, Canterbury, NZ, see below (lucerne produced 12.9t DM/ha compared with 6.6t DM/ha for ryegrass/white clover pastures in Year 8).

5. Environmental Benefits

Lucerne can extract rather than leach nitrate i.e. “clean up” N contaminated sites. This is due to its taproot extracting N at soil depths greater than other pasture species’ root systems. This extraction can be used advantageously in areas near waterways where leaching is potentially an issue or in areas that receive high applications of nitrogen such as dairy effluent areas. This benefit is not currently captured well but is an option to incorporate into farming systems.