Waikato farmer’s trial aims to boost summer feed resilience

Phil Weir and Katherine Tozer assess multi-species options to support hill country dry-stock farmers to fill summer feed gaps. Photo / Supplied

As climate variability increases, farmers need resilient summer forage crops. With pasture quality falling during mid-and-late-summer, Waikato farmer Phil Weir took part in a trial which explored mixed-species, single-graze forage crops that can fill the feed gap. Delwyn Dickey takes a closer look for the Our Land and Water National Science Challenge

Phil Weir is a busy man. Along with running a family dry-stock farm in the Waikato he is also a farming advisor with AgFirst and has recently completed a Nuffield Scholarship.

With a changing climate becoming more variable and warmer, and drier summers with droughts becoming more common in northern Waikato and Northland, Weir saw a need to move farm systems away from using supplements over these drier months, as they would only increase in the future.

“Every time you turn on your tractor to feed out, in a dry-stock context, you’re losing money,” he said.

His operation grows dairy and dairy-beef calves year-round. Summers have become tough as pasture quality suffers in the dry and the heat.

“Summers are hard for all animals, but particularly on calves,” he said.

“Trying to increase their weight from 100 kg to 200 kg over the first summer can be difficult. All the options available for feeding in summer create an imbalance in your workload.

“You’re losing your repair and maintenance time or having to take on casual staff. Ideally, we’re looking for an in situ crop instead.”

Weir sometimes grows a monoculture crop like kale for his animals. He hopes that adding multiple species of plants that grow well in the area would result in less pest pressure, less weed burden, less spraying and more dry matter. Less tractor use would also see lower emissions.

Weir believes there needs to be a way of making it easier, especially with more calves likely to be coming onto the market due to Fonterra signalling changes with bobby calves.

This is what prompted him to get involved with AgResearch scientists Katherine Tozer and Tracy Dale to find summer-safe multi-species mixes for summer forage crops as part of a Rural Professional Fund project funded by Our Land and Water, with trialling carried out on his farm.

The trial process

The study was narrow – focusing on the agronomics of the various mixes. This range of simple four-species mixtures along with a couple of hyper-diverse mixtures containing over 10 species was compared with a brassica monoculture.

The most diverse mixture included 21 species: rape, oats, plantain, red clover, cocksfoot, prairie grass, chicory, tall fescue, meadow fescue, sulla, sunflower, perennial ryegrass, hybrid ryegrass, lupin, lucerne, timothy, strawberry clover, crimson clover, balansa clover, white clover and vetch.

The 11-species mixture included: rape, plantain, red clover, chicory, buckwheat, phacelia, pea, crimson clover, white clover, vetch and Triticale kudos.

Rape (a brassica) was the monoculture crop and was also used in the simpler mixes, along with a cereal (oats), plantain for ground cover and red clover.

Preparation for the trial involved spraying off the site with a mixture of both a non-selective herbicide and insecticide, with fertiliser applied a week later. Discing, power harrowing and rolling followed.

In mid-October, multiple plots of about 20 sqm were established. Seeds were drilled in at a depth of 1 cm with a width of 1.5 m and row spacing of 15 cm.

There were multiple plots, including a monoculture plot of rape, oats, plantain and red clover. Others had each of the species dominating a mix at a ratio of 61 per cent by weight and 13 per cent for each of the rest, another had equal amounts of the seed.

As there were concerns some of the seed could be buried too deeply this wasn’t rolled, diammonium phosphate was hand broadcast and an application made of Slugout.

The seedbed on the two paddock-scale case studies, which were about 1.3 ha in size, was prepared the same way as the smaller plots. A Kuhn Triple disc drill was used to sow seed in the paddocks. The first paddock was rape-dominant with the second the 11-species mix.

Sprays to control broadleaf weeds and insects were used in November with the monoculture rape crop sprayed for white butterflies in January.

It became clear things weren’t going quite to plan when the red clover seed had a very low germination rate – less than 25 per cent compared to well over 70 per cent for the other seeds, and 97 per cent in the case of oats.

This saw the four-seed mixes become three-seed mixes. This would normally be picked up through emergence testing of the seed in a glasshouse prior to the trial getting underway. But Covid-19 restrictions stymied this step, with testing taking place at the same time as the start of the trial.

While there was more rain than usual during spring, which got the plants up and running, a dry summer followed. This may have been behind the plantain failing to thrive over the heat of summer, only coming into its own in late February for a second grazing.

Before the crops were ready for grazing in mid-January, samples were taken to determine how much dry matter was produced across each of the plots and what that meant for metabolisable energy. This saw plant matter cut to ground level, weighed, shredded and dried.

Challenges, costs and benefits

Many of the species in the 21-species mix didn’t perform well.

“A lot of the species established, but then died and contributed little to the overall yield,” Tozer said.

“There was also a high proportion of yield from sunflowers. but they’re poor in terms of feed value.”

While the 21-species mix had reasonable dry matter and metabolisable energy, sunflowers could be a bit ‘hit and miss’ with cattle, she said.

“While cattle will eat the leaves, they will sometimes avoid sunflower stalks if there is other feed available.”

The stems make up a big portion of the sunflowers’ dry matter.

Adjustments for this saw the mix slide in energy value as a consequence.

“The cost of producing metabolisable energy with the 21 species mix was more expensive than the rape monoculture because the cost of the seed is so expensive,” Tozer said.

“Even with no weed or pest control, it was still more expensive because of the seed costs.”

Oats in mixes proved to be very effective at suppressing weeds, even at low sowing rates. But oats fell down in a big way by going to seed well ahead of the rest of the forage crop. By the time the stock was put on in mid-January, it was in very poor condition.

Recommendations

Both Weir and Tozer recommend Triticale should be looked at as the cereal in the mix in the future. It might not be as aggressive at suppressing weeds, but its seedhead timing fit better.

By the end of the trial, the most promising option was a simple rape-dominant mixture that contained rape, plantain and a cereal. It had a high energy yield, low weed abundance and a low cost per unit of metabolisable energy.

Tozer emphasised that, while the results were interesting, this was one summer trial on one farm.

She said more research on more farms over several years was needed.

Table 1: Herbage production, metabolisable energy content, energy yield and energy cost for three mixtures in the small plot study, and the two case study paddocks, on a dry-stock farm in Waikato. SED: standard error of difference. Image / Supplied

More about the trial

Summer-safe multi-species cattle pasture

Why: To evaluate the performance of a variety of diverse summer seed mixes against a monoculture single graze crop, with the aim of developing more resilient forage crops that provide high-quality feed economically with lower inputs.

Where: An 0.07 ha plot study and two case study paddocks on a beef finishing property at Te Pahu in the Waikato.

Who: Weir Weir (AgFirst), Katherine Tozer (AgResearch), Tracy Dale (AgResearch), Angus Peterson (Farmlands), Hamish Johnston (Agricom) and John Foley (PGGW Seeds).

What:

• Simple mixtures provided a viable alternative to a brassica monoculture based on energy yield and energy costs. The most promising option was a simple rape-dominant mixture, which contained rape, plantain and a cereal (see Table 1 above). It had a high energy yield, low weed abundance and a low metabolisable energy cost
• Hyper-diverse mixtures did not provide energy yield or energy cost advantages when compared to a simple mixture
• Plantain contributed little to total dry matter in mid-summer but provided forage at the end of February for a second grazing
• The cereal established rapidly and reduced weed ingress in the rape-dominant mixture harvested in mid-summer
• A diverse mix may have lower weed ingress, but herbicide options are also limited