Supplementary feed

La Niña explained

By Phil Duncan

The team at WeatherWatch look ahead to see what farmers may have in store for the summer growing and harvesting season.

La Niña this and La Niña that – it’s sometimes easy to think that when La Niña is forming, it’s like a switch and it’s either turned ‘on’ or ‘off’ – it’s not.

While the actual setup of La Niña is, in essence, simple, the way it impacts New

Zealand is not.

So without breaking your mind, we thought it would be good to share with you how La Niña can impact NZ – but also, why your local weather may sometimes do the opposite of what you might expect.

To keep it simple, La Niña is measured in the equatorial Pacific Ocean and NZ is a long way from the tropics, in fact, we’re halfway to Antarctica. So just like if there was an earthquake at the tropics, it needs to be a big one to impact NZ with any risks. Same goes for La Niña – if it’s weak and spluttering, then the usual

Roaring Forties belt of windy weather in the Southern Ocean will still carry on impacting NZ.

Here’s the analogy which I think best explains La Niña and why it sometimes impacts NZ – and sometimes doesn’t.

Imagine NZ (both the North and

South Islands) are one big traffic island and we have two highways of weather merging over us. The first is the main highway of weather traffic – the Roaring

Forties. The entire South Island is in the Roaring Forties belt of westerlydriven weather and it goes up as far north as Whanganui. This is like the

‘State Highway One’ of weather in NZ; it dominates most of our weather and it has the busiest lanes of weather traffic in our part of the world. But during La

Niña seasons another lane feeds in from the north, merging with the Roaring

Forties over the NZ area. This means we can have a La Niña setup one week – full of cloud in the north, higher humidity and east to north east winds nationwide – followed one week later by a burst of windy westerlies, which kicks that La

Niña pattern to the kerb, putting a pause on La Niña weather conditions in NZ and a return to ‘normal’ weather for NZ.

This simple process can have a 180-degree dramatic difference to your local weather.

Let’s look at Hawke’s Bay and Gisborne, for example. While all of NZ is forecast to be warmer than average this month, these regions are at the lower end of that scale due to more La Niña easterlies. Winds off the sea aren’t as warm as winds coming from inland where daytime heating adds more oomph to it. But reverse that with a westerly and these eastern regions can go from cloudy, drizzly and a cool easterly, to sunny, hot and dry with a temperature in the 30s. What many would consider the opposite of La Niña weather.

So for La Niña to really override that ‘State Highway One’ of windy westerly weather, it needs to be a very powerful, dominant La Niña.

If you think back to the start of this year, La Niña didn’t end the droughts in northern NZ, they actually got worse as northern rain failed to arrive.

Why did it fail? Because La Niña wasn’t very dominant, powerful or long-lasting.

This summer La Niña is again leaning towards forming, but is also looking short-lived (likely faded by March) and so once again may not have the big impact some Kiwis may expect, because – as a reminder – it’s not a switch that is either “on” or “off” for our weather. It’s simply another lane of weather traffic to factor into our usual chaotic weather here in the South Pacific.

It’s also not just these two weather

A great example of how La Niña and our usual westerly patterns can merge right over the top of New Zealand. A really clear example of why La Niña is not a one-sizefits-all forecast.

“Imagine NZ (both the North and South Islands) are one big traffic island and we have two highways of weather merging over us.”

Current risk of La Niña forming.

patterns impacting us that helps bring changeable variety, it’s our mountains and ranges too.

You would all likely know that certain wind directions in your local part of NZ means you have a higher chance of sun or cloud, rain or dry, hot or cold. La Niña summers tend to increase the chances of easterlies in the top of NZ and nor’easters further south. So regions to the opposite of that will be hotter and drier. For example, Waikato, Manawatū, Horowhenua, Whanganui, through the Southern Alps, Central Otago and Northern Southland all have chances of a hotter, drier summer – but only when we have those east to northeast flows. When the westerlies return from time to time that means western areas get more clouds and lower temperatures. But some – like Central Otago and South Canterbury and Northern Southland – can be dry in both those setups, hence the increased risk of a drier summer there this year.

Finally, there is also the ‘wild card’ factor – a potential single weather event that entirely reverses all the long-range forecasts, not because the data was wrong but because NZ is simply so tiny compared to the ocean surrounding us. So one tropical cyclone can hit almost anywhere in NZ and reverse what was forecast for an entire month, maybe two if big enough. Stubborn high pressure zones can also get in the way north of NZ and block sub-tropical rainmakers for weeks, only to have big rainmakers just miss us to the west or east.

So, this summer be prepared for more changeable weather patterns, but also understand that La Niña is measured a long way from where some of us live, so any La Niña headline you see should be balanced with the fact NZ is basically two large mountainous islands plonked halfway in the Roaring Forties belt of westerly-driven weather. n Phil Duncan of WeatherWatch says farmers should be prepared for more changeable weather patterns this summer.

How La Niña forms.

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Waikato farmer Marty Hitchcock has been using a targeted feed regime to increase the quality of his pasture and is seeing good results.

Combating low-quality pasture

Despite nutritional deficits in pasture hampering milk production for many farmers across the country, Waikato farmer Marty Hitchcock is about 4.5% ahead of last season thanks to a targeted feeding regime.

Hitchcock milks 500 cows on 200 effective hectares in Rotorangi near

Cambridge. He says this season’s pasture growth has been prolific, but its nutritional value is lacking.

“Like last season the grass has been flush, but it doesn’t have the goodness in it. So we’ve had to supplement our herd to avoid production losses and keep our cows in good condition,” Hitchcock says.

“We started herd testing for the first time this season. This means we have been able to identify our top producers, make sure they have plenty of feed and don’t lose too much condition. With the high price of feed, it made sense only to buy the feed we needed and make sure we got the best return on our investment.

“We’ve kept up our in-shed feeding to 5kg DM per cow a day the whole way through. We use a combination of feed ranging from soy hull and corn DDG to canola meal and oat hull. This feed makes up about a quarter of our herd’s diet and balances out what they’re not getting from grass.

“We also added molasses this year, which has helped us hold our production for longer. Most of our production gains came between mid-October and last week (early November). So, the big gap in production we had between seasons is now closing up.”

His proactive approach to feeding his cows has also paid off during mating.

“Our herd went into AI in good condition and we’ve been really happy with our submission rate. We just finished AI this morning, so I am looking forward to seeing what our non-return rate is this season.”

GrainCorp Feeds technical manager Ken Winter says fewer sunshine hours have resulted in pastures with inadequate ME (metabolisable energy) and sugar levels.

“If, like Marty, farmers have invested in feeding their cows adequately to date and managed feed well to meet their herd’s requirements, they should have avoided a drop in production,” Winter says.

“They may in fact be ahead, but could have missed out on some expected margins because cows haven’t had the usual amount of quality pasture seen in better seasons.

“Farmers who have invested in extra

“Farmers who have invested in extra feed to date to make up any shortfall should have seen a positive impact on cow submission rates and conception rates during mating.” Ken Winter

feed to date to make up any shortfall should have seen a positive impact on cow submission rates and conception rates during mating. “This will be noticeable in cows’ body condition and their ability to respond to what feed is now being offered.”

This season’s high commodity prices have increased the price of supplementary feed. But he says, for many of their customers like Hitchcock, their investment is paying off.

“Although it’s been more costly, the investment many of our farmer customers have made in feed has been worthwhile to maintain their herd’s production. Some are even tracking ahead despite the challenges of the season and that comes down to timely decision-making and consistency,” he says.

Winter says the question now is when pasture nutrition will deliver on expectations.

“We are only just starting to get some good sunshine. The mistake you don’t want to make is cutting back on concentrates (energy-dense feed) and making the cows eat more lesser-quality feed. With a high payout looming, you don’t want to risk undoing all your good work by short-changing your cows now.”

He also says turning surplus pasture into silage in these situations makes sense.

“When the pasture comes right, we can then look at reducing the amount or spec of the supplement depending on how well the cows are converting their feed and how that translates into margin,” he says.

Ken Winter of GrainCorp Feeds says the mistake you don’t want to make now is cutting back on energy dense feed.

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Experimenting with grazing

By Cheyenne Nicholson

A Waikato farmer who is not afraid to try new things is getting surprising results from a deferred grazing trial.

Once-a-day farmer Andrew Macky is all about experimenting. From starting a YouTube channel to trialling deferred grazing, he’s not afraid to give new things a crack.

Speaking at last month’s SMASH webinar, he shared his experience with deferred grazing.

Macky is the farm manager on the family farm at Paterangi, Te Awamutu, with his wife Holly and their children William, three, and Frankie, one.

The 100ha System 2 farm milks 320 Jersey cows and has been in the family for more than 100 years. Owned by his parents, his father also works the farm.

The farm is split into two herds; one run by his father, the other run by Macky. It’s a slightly unusual setup, but it’s an idea he got from working in the UK.

“We have a higher-producing herd and a lower-producing herd. Dad and I just go through and pick the ones we think are producing better. I look after 175 cows in my high-producing herd and dad has the rest in the low-producing herd,” Macky says.

The high-producing herd is fed a mix of grass, maize and palm kernel throughout the year and housed on the peaty flats that hold on a bit longer in summer. Cows are fed on a feedpad via a mixer wagon. At the moment, each cow gets 2kg maize and 1.5kg palm kernel; this changes during the season depending on pasture covers. This year, owing to a hard, cold spring, he added molasses into their diets as well for some added energy.

“Dad’s herd we keep all the young cows and lower-producing older cows, and they’re on a grass and chicory diet, with no maize or PKE. The country they are on dries out quicker, hence feeding them chicory in summer,” he says.

Last year he became intrigued by the concept of deferred grazing, a low-cow method of pasture conservation and renovation. Also called summer fallow, deferred grazing takes ryegrass-based pastures out of the grazing rotation over late spring and summer to allow them to reseed and build root reserves before being grazed in the late summer or early autumn.

Typically, clover will be the first thing to bounce back, with ryegrass taking slightly longer to germinate.

With several ex-cropping paddocks in need of resowing, he set to undersowing these the year before but wasn’t happy with the results, so he decided to give

Waikato farmer Andrew Macky likes to try new things and has been trialling deferred grazing and is getting great results. Andrew with children Frankie, one, and William three.

The 320-cow herd is run in two mobs and milked once-a-day on the System 2 farm. The high-producing herd is fed a mix of grass, maize and palm kernel throughout the year and the low-producing herd on grass and chicory.

A paddock saved for deferred grazing before it is grazed. The same paddock showing the regrowth as a result of deferred grazing.

deferred grazing a try. He locked up five paddocks for 120 days, starting in midOctober.

“There can be long-term gain there, but you do have to expect a drop in production when you put them on the deferred grazing paddocks – they’re long and stalky and not what they usually munch on,” he says.

“It could be argued that given the time of year they went on, they would have dropped production anyway due to the general lack of grass, but I think they dropped more than they would normally.”

That said, he says the production levelled out and he has been pleased with the outcome of the trial and has learnt a few things along the way.

“I did a few things wrong for sure. It was all a bit of trial and error. I locked up the paddocks a bit too early for one. I should have done a weed spray before I locked them up, as we ended up with a few thistles and dock, and other things. I also put nitrogen on them, which I shouldn’t have done. I should have let them grow by themselves because the nitrogen meant the ryegrass outgrew the clover a bit,” he explains.

The cows started grazing these paddocks once they had gone to seed and were pre-topped before the cows went in to try and minimise the ‘rubbish’ the cows would leave behind. Two of the five paddocks ended up being baled for hay due to worries about seed heads rotting away after a decent dose of rain.

“The seed head was unreal. DairyNZ came out and we estimated about a 70-80kg per hectare seed drop, so they reseeded themselves really well,” he says.

While a few things didn’t go quite right, a big bonus was being able to extend the rotation from 20 to 40 days.

“The results were great, the reseeding went really well and we ended up with good, thick, green grass. We had a few weeds in the mix, but there was a lot of lush grass,” he says.

“The real test will be how it lasts over the next year or so. It’s a good theory and has worked well, so I may look at it again in the future.” n

Showcasing NZ farming

Andrew Macky takes great pride in his work on-farm and is sharing his day-to-day life with the world. A year ago he started a YouTube channel and vlogs his daily life on-farm.

“No one was really doing it on a big scale here in NZ, so I saw a bit of a gap in the market. I got a camera and started filming.

“It’s a lot of work for minimal output, but I’m hoping that will change in the future,” Macky says.

“It’s a really neat way of educating people and showing them what actually happens on-farm. I’ve talked about everything from our once-a-day system to the deferred grazing and get lots of great feedback.”

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App to help fight nassella

By Tony Benny

Farmers battling weeds on their farm have a new tool to help in the fight against nassella tussock weed.

Anew web app has been released to help farmers manage a costly weed that in the 1940s brought farming in drought-prone land in Canterbury and Marlborough to its knees and which, despite continued control efforts, still poses a serious threat.

Nassella tussock is the only weed in New Zealand to have its own Act of Parliament, the Nassella Tussock Act 1946. So severe were infestations of the non-palatable, readily-spread-by-wind weed in the 1940s, that some farmers abandoned their properties and large gangs of workers armed with grubbers were employed to bring it under control.

Grubbing is still the principal method of control and it’s compulsory for landowners to dig out any nassella plants they see in spring, when it flowers and is easiest to identify. But not all farmers take well to being told they have to grub the weed and that can be a source of conflict between them and the regulating authority Environment Canterbury (ECan).

So AgResearch scientist Graeme Boudôt and his team, with funding from the Ministry of Business, Innovation and Employment (MBIE), in collaboration with ECan, have come up with a tool to show farmers what will likely happen, depending on whether they grub as instructed or if they fail to take action.

Bourdôt, who has spent decades researching nassella tussock, says this app follows in the path of another similar tool for giant buttercup, which AgResearch developed to support dairy farmers in weed management decisionmaking.

“The nassella tussock app draws on decades of research into how nassella tussock plants grow and contribute to the population growth of the weed in dryland sheep and cattle pastures. It enables the user to see how different frequencies, intensities and seasons of grubbing will affect the future number of nassella tussock plants on a block of land and on an adjacent block of land,” Bourdôt says.

“Efforts to eradicate nassella have proven unsuccessful, so now it is a case of living with it and managing it. This is where the app can give the best information to people on how to manage the weed using grubbing to avoid uncontrolled population growth that can lead to increased future grubbing costs, losses in farm productivity and unacceptable impacts on a neighbour.”

Although eradication has proven elusive, a 17-year study in Canterbury, published in 2016, showed that the population density of the weed across 878 invaded farms in the Hurunui district of North Canterbury is stable at about 15 plants a hectare. Grubbing of the plants before seeding each year – the management tactic practiced on these farms – has been responsible for maintaining this ‘equilibrium’, according to on-farm experiments and modelling.

Left uncontrolled, the modelling indicates that the weed’s populations will increase, potentially reaching the economically damaging monocultures of the past, which in some cases forced farmers to abandon their properties.

“Here’s a scientific model that tells us if you stop grubbing now, this is what your farm is going to look like in 25 or 50 years and this is what the impact will be on your neighbour,” he says.

ECan biosecurity officer Matt Smith says many decades of hard work since the 1940s have returned plant numbers to a manageable level.

“The app is a great way for land occupiers to model different control scenarios on their properties. It clearly demonstrates that annual control is the best method to decrease or maintain plant numbers,” Smith says.

“At Environment Canterbury, we have used the app to measure how long it might take an unknown infestation to turn from a few plants into a major issue.” n

AgResearch scientist Graeme Boudôt has spent decades researching nassella tussock weed and now he and his team have come up with an app for farmers to use.

MORE:

The app can be found at https://nassellatussock-population-model-nz.agresearch. co.nz/

Sustainable way to cut emissions

UK and Irish seaweeds may significantly reduce GHG agricultural emissions and provide extra health benefits when used as a supplement for farm animals. Photo: Wolfgang Hasselmann

The use of seaweed as a supplementary feed in farm animals could lead to great sustainability and with more than 15,000 kilometres, there could be plenty of opportunities for New Zealand to reduce their emissions.

While the COP26 debated methane and the US and EU pledged to reduce agricultural methane outputs from ruminant livestock by upwards of 30% by 2030, scientists at the Institute for Global Food Security (IGFS) at Queen’s University Belfast were researching feeding seaweed to farm animals in a bid to slash methane by at least 30%.

Seaweed has long been hailed a ‘superfood’ for humans, but adding it to animal feed to reduce methane gas released into the atmosphere by ruminants’ burping and flatulence is a relatively new idea. Early laboratory research at IGFS has shown promising results using native Irish and UK seaweeds.

Previous research in Australia and the US generated headline results – up to 80% reductions in methane emissions from cattle given supplements from a red seaweed variety. These red seaweeds grow abundantly in warmer climates, however, they also contain high levels of bromoform – known to be damaging to the ozone layer. Seaweed indigenous to the UK and Ireland tends to be brown or green and does not contain bromoform.

UK and Irish seaweeds are also rich in active compounds called phlorotannins, found in red wine and berries, which are anti-bacterial and improve immunity so could have additional health benefits for animals.

Now the IGFS science is moving into the field, with trials on UK farms about to begin, using seaweed sourced from the Irish and North seas as a feed supplement for cattle.

One three-year project is in partnership with the UK supermarket Morrisons and its network of British beef farmers who will facilitate farm trials. The project also includes the Agrifood and Biosciences Institute (AFBI), in Northern Ireland, as a partner.

A second project sees IGFS and AFBI join a €2 million (about $3.2m), international project led by Irish agency An Teagasc to monitor the effects of seaweed in the diet of pasture-based livestock. Seaweed will be added to grass-based silage on-farm trials involving dairy cows in Northern Ireland from early 2022.

As well as assessing methane emissions of the beef and dairy cattle, these projects will assess the nutritional value of a variety of homegrown seaweeds, their effects on animal productivity and meat quality.

IGFS lead Sharon Huws, Professor of Animal Science and Microbiology within the School of Biological Sciences, says she expected the combined research to evidence a reduction in greenhouse gas emissions of at least 30%.

“The science is there. It’s simply a matter of providing the necessary data and then implementing it. Using seaweed is a natural, sustainable way of reducing emissions and has great potential to be scaled up. There is no reason why we can’t be farming seaweed and this would also protect the biodiversity of our shorelines,” Huws says.

“If UK farmers are to meet a zerocarbon model, we really need to start putting this kind of research into practice.

“I hope IGFS and AFBI research can soon provide the necessary data and reassurance for governments to take forward.” n

“The science is there. It’s simply a matter of providing the necessary data and then implementing it.” Professor Sharon Huws