Lucerne key in gaining more punch from feed, team finds
Prof Derrick Moot plucks off a fresh stalk of lucerne which he fondly calls "God’s own plant".
The nitrogen-fixing legume is nestled in six fields within the Lincoln University grounds where the academic and his small team are looking at gaining more punch from its feeding rotation.
Lambs contentedly munch on the perennial, oblivious that they’re contributing to important science.
Once a minority player, lucerne — known as alfalfa in other parts of the world — has gained a following among dryland farmers because of its high energy, yield and resilience.
A large tap root reaches deep into the soil to access nutrients and water.
More commonly grown for grazing here, as opposed to being used as hay forage in other areas such as North America, it’s become a pivotal part of the university’s dryland pastures research (DPR) programme.
Initially a climate change project, the focus is on feeding animals well in tough dryland country typically on the East Coast from Central Otago to Gisborne.
The goalposts shifted this month with its genesis becoming even more valid, as the Government announced that farmers face paying a price for their agricultural emissions from 2025.
Prof Moot says the sheep and beef sector has reduced its methane emissions by 30% and its emissions per kilogram of meat over the past 30 years.
Total emissions have gone down because dairying expanded, but better feeding of animals is behind productivity gains going from about one kilogram of methane per 1kg of meat to now 0.7kg of methane for 1kg of meat, he says.
Fewer ewes with a higher lambing percentage have contributed to this with a faster growth rate of lambs to heavier kill weights.
He says more improvement needs to come from productivity, with lucerne playing its part on dryland farms by better feeding of ewes and lambs during the vital lactation phase.
"That’s what we’ve done and we need to continue to do that, but that’s not part of the conversation at the moment.
"There’s a lot of conversations of other forms of trying to reduce our emissions predominantly cutting numbers, lower-emitting sheep, vaccines, seaweed, a number of things experimental.
"How does a farmer do it right now? The only way of doing it is feeding your animals better and getting rid of your lambs and cattle quicker and having fewer of them because they’re more fecund. If you have fewer ewes during the winter then you will have reduced methane as well."
He says the jury might be out whether other countries will follow our world-first legislation, but it’s going to land here so we have to deal with it.
An educated guess is that 20 years ago few dryland farmers would have got rid of lambs at weaning at 90 to 100 days so just about all of them were going through into December, January and February.
Some of those farmers would now be getting rid of 60% to 70% of their lambs at weaning and take another big cut a month later.
Another productivity gain is that their ewe lambs will be growing better so they can be mated as hoggets, rather than them being merely a grazing expense for a year — "not a great methane emission reducer".
He got a position at Lincoln University and thought who’s going to be most affected "if" climate change happens.
"Climate change was on the agenda and I’d been working on wheat yields in different parts of the UK.
"It was [in the minds] of the agricultural science community here in New Zealand, but there wasn’t a lot of conversations outside of the science community. Indeed, when I first started talking to farmers, I didn’t mention climate change and just said you are dealing with climate variability and how can we create an insurance policy for you."
There wasn’t a lot of acceptance from either the public or the rural community then, hence the diplomacy.
"In fact my first lectures at Lincoln University were on climate change and a couple of people have told me they actually put my lecture notes in the bin because they thought they were nonsense because I was bringing back this information, the data and the models from the UK. They laughed about it afterwards, but that’s how it started."
A few years followed as he put together a research project with a focus on lucerne after wondering why more use wasn’t being made of the plant in farming.
Lucerne had fallen out of favour as irrigation gained pace and because of its limiting reputation as a cut-and-carry forage. A survey found that farmers had lucerne, but made it into hay or silage and fed it to stock in the summer.
Prof Moot began questioning why lucerne wasn’t being grazed. The answer didn’t arrive immediately, but eventually was straightforward.
Farmers had been told to wait until it got to 10% flowering, by which time it was 70-80 centimetres tall and virtually a "tree trunk".
That management advice had come from a cut-and-carry system in the United States for providing feed for dairy cows in feedlots — a foreign scenario to hill country sheep and beef farming here.
The problem with this was that the plant wasn’t useful when it was needed most at the busiest time of the farming year when animals were lactating. August-born lambs need feeding that month, not by late October to mid-November when lucerne had reached 70cm.
Weaned lambs would go on the harvested lucerne around Christmas, but the animals’ guts took a few weeks to adjust and the timing of the system was out of kilter as the plant’s growth rate slowed in summer when the lambs started growing quickly.
The first step was to "pick the plant to pieces" and get the science to stack up to try to make it more useful. Lucerne essentially works like a poplar or willow tree, storing nitrogen and carbon in the ground in autumn before bursting back into life in spring.
Understanding its life-cycle, the researchers realised they could change its management so ewes and lambs could graze on high-quality feed around lambing, assisting ewe lactation and helping them keep their condition to get back into cycle more easily later on.
Stock are now grazed from early August at Lincoln University.
They then move on to subterranean clover to work out a more robust package for growing it. This clover is grown in some of the driest parts of North Canterbury and Hawke’s Bay, where animals in the lactation period are vulnerable on farms with two to three months of summer-dry weather.
The self-seeding annual germinates in the autumn, producing a rosette about the size of a saucer in the winter and then runs as the days get longer in early spring, a growth period that’s a month earlier than white clover.
Prof Moot said the key part of that study was working out how to turn 10kg of seed in the first paddock to 1000kg for the farmer.
That involved letting the first paddock set seed with grazing only by cattle initially and concentrating on a small area first.
So the second step was to apply the lessons on farms and the last part of the DPR study the past five years has been writing up some of the case studies in the Hill Country Futures programme with Beef+Lamb NZ and making them visible to people and showing their impact.
Early adopters such as Doug Avery, at Marlborough’s Bonavaree Farm, gained a profile and acted as a catalyst for others to follow.
Once the DPR team could prove the model worked the challenge was to evolve the principles to other parts of the country and environments beyond summer-dry farms.
Banks Peninsula’s 5500ha Willesden Farm, managed by Matt Iremonger, has gone from five to 350ha in lucerne the past five years.
Lucerne is being used in a specialist way on the property for hoggets rearing their first lambs to make sure they’re well fed during lactation and provide a boost for the still-growing animals.
A Hill Country Futures study has measured this to be two and a-half to three times better than the grass yield over contrasting average, dry and wet seasons the last three years. Lucerne’s 14 tonnes of dry matter a hectare on average compares with the resident pastures’ 6t/ha.
Lincoln University studies have shown twin lambs grazing on lucerne before weaning routinely put on 300 grams per head a day.
"That’s what you need," Prof Moot says.
"If you’ve got a dry farm you’ve got to get from a 5kg animal to a 35kg animal in 100 days. The maths says you have to grow 300g per day. The average growth rate is probably 150g per head a day and the difference for those on grass-based pastures is that the ryegrass is absolutely fine when you start in spring but then goes to seed just as you’re getting large lambs starting to eat themselves and your ryegrass quality starts to drop.
"Animals will always do well in lactation because they can feed on mum, and mum will lose condition so the advantage of lucerne or red clover, or whatever herbs with legume it might be, is that you can maintain mum’s condition as well as growing the animals quickly during that lactation period."
By the same token, cull ewes fed on lucerne can get off the farm earlier and avoid freezing works bottlenecks.
The animals are generally fed on mono-cultures of lucerne in the likes of Central Otago, Mackenzie district, North Canterbury, Blenheim or Hawke’s Bay, but systems vary depending on the location of a farm and its moisture levels.
Red clover is sometimes exclusively fed on farms such as John Chapman’s Inverary Station — partly to also help him take control of weed grasses — before being replaced by Italian ryegrass after a few years or put in permanent pasture with timothy grass.
Inverary continues to get rain through winter to summer most years, but the principles of the lucerne lessons still apply.
Prof Moot says hill country grass is usually nitrogen deficient as can be seen comparing urine patches with nearby pasture.
Many hill country farmers don’t put on nitrogen fertiliser because of the cost of applying it by aircraft and if they do, it’s usually 100kg of nitrogen in the spring, he says.
He says putting nitrogen-fixing legumes in can fix this, with the likes of lucerne, red and white clover providing about 30kg of nitrogen per tonne of legumes grown. Summer-dry farmers without the large rainfall of other farming areas don’t have to deal with nitrate leaching as the nitrogen stays in the soils to be used by grasses and legumes later.
A lucerne stand will generally last five to 10 years. The former might be in an irrigated paddock where weeds might sprout up, while dryland properties working with the DPR team last seven-plus years. After that grazing period Italian ryegrass or another crop might be planted to mop up nitrogen in the soil, lasting 18 months to two years after lucerne is removed.
Farmers can concentrate on removing weeds then and go back to lucerne.
Another Hill Country Futures study at Inverary found 30t/ha of Italian ryegrass dry matter was grown without nitrogen following three years of it being in red clover pasture.
Similar dryland studies have shown good gains after lucerne is grown at Lincoln University.
Their grazing management has been picked up in South American nations such as Chile and Argentina for beef cattle grazing and in Australia, with interest extending to rangelands farming in the United States.
For the most part it’s been a smooth ride, but there have been challenges along the way and in 2014 a lot of farmers flushed their ewe flocks on lucerne just before mating during a wet autumn.
A reduction of 20% ovulation was the result and a PhD student was brought in to work out that the compound, coumestrol, was being produced in a wet canopy and affecting the ovulation rates.
The solution was to graze them until up to two weeks before the rams go out. Farmers were also advised to make grass available in a wet autumn.
Once they’re pregnant they can go back on lucerne because it doesn’t make a difference, says Prof Moot.
"That’s been the journey. It’s been doing things and farmers finding its become a problem and how do we fix that. We knew there was an issue with coumestrol and it could happen, but we didn’t know what advice to give and we needed to come up what to do — two weeks before get the animals off and you will be fine."
New for the team is a dryland regenerative agriculture trial with a lucerne, sub-clover and cocksfoot system compared with regenerative farming on an 8ha farmlet at the university.
The performance of those systems in high and low fertility conditions will be gauged over five to six years to test them with science. They will measure changes in the soil, pastures and livestock and calculate greenhouse gas emissions and their economics.
Prof Moot has his own thoughts about what it will reveal, but he’s open to finding a better system.
Over the past 20-plus years sheep and beef farmers have witnessed the retreat of their finishing country into the hills from higher-returning dairy farms or dairy support land.
Dryland farmers traditionally selling store lambs found themselves with a limited market and had to re-invent themselves into at least finishing some of their own animals.
Prof Moot says that’s 85% a feed story.
He says the difference between now and when the project first started is that East Coast farmers have hope.
Lucerne has become part of their system rather than an oddball, he says.
" If you spoke to some of those Marlborough farmers 20 years ago when they were being ravaged by drought year after year things were getting it pretty tough and the same in Hawke’s Bay and the Wairarapa areas. So I think what we’ve done is give people solutions that they’ve been able to pick up and apply.
"They’re not perfect and there’s weed issues, but there is opportunity and there’s hope and a whole system they can work with a whole network of people doing it."
Looking ahead, there’s a research application in with the Ministry for Primary Industries to go back and profile the economic and environmental footprint of farms involved with DPR.
"Climate change was always there in the beginning of the project. I never thought we would be trying to reduce methane emissions out of animals.
"When I did climate change 30 years ago it was always about carbon dioxide in energy and still is in my opinion, but New Zealand has decided we are going to do methane so now we have to measure it."
