Tuesday, October 2, 2012

Lucerne Based Dairy Farm- More Feed, Less Irrigation, Less Nitrate Leaching

Richard Campion is a lecturer at Lincoln University; he presented a paper to the 18th International Farm Management Congressheld in Methven last year. His paper was titled “Utilising Lucerne Potential For Dairy Farming”.

In his paper he modelled the Lincoln University Dairy Farm using 90% lucerne and 10% winter crop. His report states that the ryegrass and white clover pastures at the Lincoln University dairy farm produce on average 17,000kg DM/ha/yr. Irrigated lucerne stands have been shown to produce 24,000kg DM/ha/yr. But the interesting point is that Lucerne has far greater water efficiency than ryegrass. For this reason irrigated lucerne can grow 25% more dry matter than pasture and it can do it with only 1/3 of the water that ryegrass needs.
So if a dairy farmer changed their irrigated pasture system to a lucerne based system, they would reduce the water required for irrigation by approximately 65%. This is a massive potential saving.

Purely from a water efficiency perspective, lucerne has a clear advantage over ryegrass pasture. This has implications from the environmental perspective such as dairy’s water footprint as well as from a cost saving point of view.

I worked on a 800 cow irrigated dairy farm in Canterbury, the power bill just for the irrigation pumps alone was $200,000/year. This is quite high because the water was very deep, the Canterbury average is closer to $60,000/year. If a farmer could reduce their irrigation power bill by two thirds, then that is a significant saving.

I read about farmers being praised for their water use efficiency by using moisture meters and other tools that allow them to irrigate much more efficiently. Which is great, but surely these farmers would be only achieving water savings in the order of 5-10%. A lucerne based dairy farm should be able to make a 65% reduction in water use!

Water efficiency is not the only advantage of lucerne. Because it is a legume it fixes its own nitrogen and therefore does not require nitrogen fertilizer like a ryegrass based system does. The average Canterbury dairy farmer spends about $80,000/year on nitrogen fertilizer. The lucerne system has the potential for significant fertilizer savings. Because lucerne does not need nitrogen fertilizer, this has an environmental advantage as well, as nitrate leaching is the main form of pollution from dairy farms.

Lucerne has a root system far greater than a ryegrass pasture. It is not uncommon for lucerne to have a root depth of 2-3 metres compared to 20-30 cm for ryegrass. For this reason lucerne roots can absorb nitrates further down the soil profile than ryegrass can, this means a lucerne stand should leach less nitrate than a ryegrass paddock. Lucerne is in fact used to clean decontaminated soils around the world.
As farmers look for methods to decrease the amount of nitrate their farms leach, lucerne must surely be an option.

Richard points out that a lucerne system will have to be managed quite differently and is quite a departure from a conventional dairy farm.
Bloat can be an issue with lucerne feed but this can be addressed with bloat drench or boluses. Richard suggests that raising all young stock on lucerne will enable them to become much less susceptible to bloat as a adult. He recommends not breeding from cows that get bloat as well.

lucerne requires care with stock on wet soils as the crown can be damaged, but this is true of ryegrass as well. A lucerne system will have to have some other form of feed in the spring as lucerne will not be ready to graze until October and the wet spring conditions risk damaging the plant.

As farmers in Canterbury look to the future, they can be sure that the battle with nitrate limits and the competition for water allocation will increase. A lucerne based dairy system will have to be managed differently, but the potential advantages especially the water efficiency and the plants ability to absorb nitrates must mean it plays a part to solving these two issues.


  1. Thought provoking article.

    Unfortunately at the moment Overseer6 models lucerne as having significantly higher nitrate leaching than pasture, apparently.

    1. Also, this works both ways - we have instances of sheep and beef farmers opting not to install irrigation and convert to dairy, as they can make better margins by converting to an unirrigated lucerne based drystock system. Lifting productivity without the capital and operating costs of irrigation and dairy.

      Either way, there is a lucerne grazing revolution underway, and it is going to have huge impacts on pastoral farming in NZ in the coming decade.

  2. I agree lucerne is under rated. Its exciting. I'm getting mixed messages reguarding nitrate leaching on a lucerne system. Your correct overseeer6 does show greater nitrate leaching on a dairy system. No one can explain why. So some further investigation shall be done.

  3. Do you subscribe to any other websites about this? I'm struggling to find other reputable sources like yourself

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