Focus on renewal
Producing more milk from pasture means there’s a lot to be gained from renewal to improve yields
Article published in NZ Dairy Exporter Magazine, February 2019
Hayden Fletcher needs no convincing about the value of pasture renewal – he’s seen some staggering results for himself. But the North Canterbury contract milker knows only too well that there’s a lot more to it than spraying out the paddock and drilling new seed.
From paddock selection right through it’s first year of life it’s critical to put effort in and do it right, he says.
Hayden is in this third season on Craigmore’s 260ha Darnley farm, near Culverden. Right in the middle of the Amuri Basin, the climate is one of extremes – scorching hot dry days in the summer and icy cold in the winter.
Craigmore has owned the farm since 2013 but the boundaries have changed over time and with the addition of a new farm dairy on adjacent land, Darnley’s area has dropped from 320ha this season. Cow numbers also dropped from 1230 last season to 970 this year. This season they are on track to produce very close to 1700kg milksolids (MS/ha) using about 500-700kg drymatter/cow of imported feed. That includes barley and palm kernel.
Getting more milk production from pasture, though, is where Hayden’s focus lies and with a six tonnes DM/ha/year range in pasture yields from the best-performing paddock to the worst, there’s a lot to be gained from renewal. “The average is about 14t DM/ha – if we could lift that by just a tonne that’s 260t DM of extra feed every year”, he says.
But the renewal process isn’t the same for every paddock with certain areas having specific challenges. Weed are the biggest headache with different weeds affecting different parts of the farm. One area was converted from sheep and there the issues are docks and browntop. “Any treading damage there and the pasture opens up and browntop is straight back into it. For most of the season the docks are really unpalatable too, so getting cows to eat down to residual can be hard in those areas. It affects utilisation and I’m not a fan of sitting on the tractor (tidying them up)”, he says.
While they’re earmarked for renewal there’s also an underlying drainage issue for those paddocks which will involve a project of its own that’s planned to take place over the next 12 months. In the meantime, cultivation of paddocks with docks is definitely to be avoided as disturbing the soil stirs up the seek bank and plants can also regrow from the tap roots that are notoriously deep. Hayden’s used a selective herbicide on the worst dock paddocks this season to see just what kind of control they can get. “We’re just seeing some starting to appear back in the paddock now, three months after spraying”, he says.
On the southern side of the farm it’s nodding thistles and twitch that cause the problems. Similar to docks, the twitch will sprout from pieces of root – although its roots are rhizomatous so cultivation can have even worse outcomes if the plant’s not killed beforehand or double sprayed. Nodding thistles, too, have a long living seed bank.
Hayden’s trialing a system to renew paddocks where thistles are a problem by spraying out and then direct drilling just the ryegrass. Post-emergence and just prior to first grazing, he’s then sprayed with a selective thistle spray. Once the residual period has passed he’s then spun on the clover seed with urea. The result has been a fantastic clean paddock and while it looks successful it won’t be until later in the season he can confidently say it’s worked well for the clover.
What he does know, based on experience in the neighbouring paddock, is that if he can’t go in and spray the thistles out after the ryegrass has established, they’re back with a vengeance. “We had a paddock where the seed arrived and while it shouldn’t have, it had clover in it, it was just too good to spray it out. So we went all out and three of us spot-sprayed it one day, but it was a big job”, he says. They’ve cleaned it up but the best, most cost-effective solution, especially timewise, was the first method.
Hayden’s also using cropping as a means to renew pastures where twitch is the issue. He’s put in crops of summer turnips, spraying the paddock out in October with the aim to direct drill it by November 1. Unfortunately, this season the weather meant the contracted was repeatedly delayed until later in November and the yield has been at the lower end of 8-12t DM/ha Hayden can expect. The turnips help him to start pushing the round out in February and, once cows are off them, the second spray before drilling back into permanent pasture hits any regrown twitch again.
Fodder beat is grown on the platform as an autumn feed and to transition cows for their winter grazing off farm. But it too gives the opportunity for a double spray and helps establish new grass, albeit over a longer period.
Once the cows go off it, late in the season the aim is to sow a catchup crop of oats which is then grazed in September by late-calving cows, if pasture is slow to get away. If pasture availability is good the greenfeed oats will be baled. They’ll produce between three and six tonnes DM/ha. Permanent pasture will go in following the oats. Getting the oats in is weather-dependent in late May so an alternative, they haven’t had to use yet, is to cultivate in the spring and prepare the paddock for regrassing, then drill the turnips and, following grazing, spray out the twitch and direct-drill permanent pasture. Having a plan B and being flexible if the weather doesn’t play the game is important. “Everything is so dependent on the season, you have to have a plan for different situations and be ready to go with something different if you have to,” he says.
Hayden was part of DairyNZ’s Tiller Talk programme which focuses on pasture renewal and one of the benefts he got out of it was the opportunity to trial what at the time was a yet-to-be commercially released diploid ryegrass cultivar. The farm has been using Base – a tetraploid and Hayden wanted a complement to it – something that was highly palatable, yielded well and could show persistence on their heavier soils with the climate extremes. It performed well in the paddock trials and has since been released as Raider by Cropmark through Ravensdown. Hayden’s used it in two paddocks he renewed in spring, combining it with Base, and he was staggered at growth rates through early December. Other pastures were taking off too at that stage with the combination of heat and rain but not anywhere near the extent the new paddocks did. “We were plating the growth rates at 180kg DM/day over 12 days,” Hayden says.
He was a little incredulous to start with but the cows told him it was right. “We were going back in there based on leaf emergence – at the 2.5 to three-leaf stage. That was 14 days.” Those paddocks had their first grazing at the end of November and by the third week in January they were on their fifth grazing. “We’d done three full rounds of the rest of the farm by that same stage.” It’s coped with the heat well and is a late header and likes the heavier soils so it’s been good in their situation, he says. Hayden’s now interested to see how it performs in the cooler, better months.
While a lot of effort goes into weed control and giving the seed every chance to establish, Hayden also places a lot of emphasis on managing the new grass through its first 12 months. Crop paddocks get a starter fertiliser to ensure they have the nutrients they need but the farm’s practice of soil testing every paddock and applying fertiliser as necessary means new grass paddocks generally don’t need additional fertiliser. They do get 100kg/ha of urea after the first grazing – six to eight weeks from sowing depending on the season. Before first grazing he does a pull test to ensure the young plants are well rooted and the cover is generally just over 2000kg DM/ha. It’s over allocated and cows are just there to nip it off to promote tillering.
“I’m not going to get too worried if they don’t get right down to residual on that first grazing but when they come back for the second one, at the 2.5 to three leaf stage, cows will be expected to hit residual.” The stems are still soft and there’s no reason why cows won’t eat into it, he says. Depending on the time of year, given that under irrigation regrassing can be done in spring or autumn, the pre-graze cover will be 2800-2900kg DM/ha or if it’s growing rapidly can be up to 3500kg DM/ha. Hayden says the key is not to damage the pasture and soils by grazing when soil conditions are wet. There’s also the temptation to over-graze it through its first season as it stands out so well against the older pastures. So sticking to the grazing rules of 2.5 to three-leaf stage and staying off it if wet is important. In autumn he’s still treating the springs own, new grass with an extra bit of TLC and will aim to graze it right down during the last round so he doesn’t have to go back into it too early in the spring when it can be wet.
Everything you do is about setting it up for life with the expectation that life isn’t going to have a five-year limit, he says.