One of the reasons farmers adopt perennial pastures is to extend the growing season.
By improving summer feed quality and responding quickly to summer and autumn rain, perennials can help reduce supplementary feeding, defer grazing from annual paddocks at the break of season and flush ewes for improved reproduction. Perennials also help address soil constraints, most notably reducing groundwater levels, waterlogging and salinity risk and providing summer cover for erosion control.
For farmers trying to address these types of soil constraints, the benefits are often enough to commit. But for many others, the cost of establishing perennials is still a risk they can’t accept.
Planfarm consultant Paul Omodei says the cost isn’t just in the seed.
“The loss of production for possibly three or four months is a significant cost,” Mr Omodei says. “Hopefully you make that up at the back end of the year, but if it’s a short finish then you’ve got the year after that to get things going.
“But, the other cost is in preparing a weed-free paddock to make sure it will give you the establishment and then the persistence in future years. The biggest loss in perennials is failing to have enough density, not getting the production, and going back to a pure annual system.”
A common way to prepare paddocks in the Manjimup-area is by growing a cereal crop the year before establishing perennials. This increases the number of knock down sprays and provides options for other herbicide treatments, while the crop also provides competition for weeds. While this strategy can also be profitable through the sale of grain, there is still the lack of production when perennials are slowly establishing.
Trial: Establishing perennials with cereals
One way to fill the production gap could be to establish perennials with cereals in the same year. Could this approach increase profits and result in a persistent stand of perennials?
Manjimup Pasture Group (MPG) tried to find an answer to this question in a project supported by the South West Catchments Council. In 2014, with guidance from Planfarm consultants Paul Omodei and Alana Starkie, MPG set up a trial at Phill, Judy and Diane Rose’s property 15km north of Manjimup. The replicated trial compared the establishment of a perennial-only mix against perennials twin-sown with Einstein wheat.
Three twin-sown treatments were tested to find the best compromise between wheat production and perennial establishment. Perennial seed was placed at a shallow depth in all treatments, while the depth of cereal seed varied between treatments, from deep (preferred by cereal), shallow (disadvantages the cereal), and deep but in its own row (skip-row) six inches from perennial rows. The deep cereal treatment was also trialled without lucerne in the perennial mix.
The perennial-only mix consisted of phalaris, lucerne and chicory (sown at a combined total of 5kg/ha). This ‘control’ treatment was also trialled with the seed treated with mycorrhiza and nutrients.
The trial showed that when perennials are twin-sown with cereals, gross margins (GM) can increase significantly in year one due to grain sales. The twin-sown treatments yielded three to four tonnes per hectare of wheat and resulted in first year GM of between $500 and $700/ha. This compared to a loss in GM of between $20 and $115/ha in the perennial-only treatments.
As expected, this grain production was off-set by reduced perennial production. After grain was harvested in January 2015, mean total dry matter (DM) was measured, with perennial-only plots averaging 1,894 kg/ha, compared to 119 kg/ha in twin-sown treatments.
Sowing cereals deep without lucerne resulted in the highest grain yield, but also the lowest perennial biomass. The poor establishment led to this treatment being sprayed out the following year and re-seeded to the perennial mix (seeds untreated). This outcome essentially mimicked the practice of growing a cereal in year one and then establishing perennials in year two.
The difference in GM between perennial-only treatments and some twin sown treatments narrowed by the end of the trial. Sowing cereals and perennials shallow had the highest GM ($450/ha higher than perennials-only) but also had the lowest perennial plant density.
The farmers involved with the trial regularly met at the property to follow its progress. While they learnt that it’s possible to establish perennials with cereals, they all agreed that the perennials established much better when sown alone.
Host farmer Phill Rose says perennials germinated well enough with cereals, but the resulting sward wasn’t thick enough.
“Probably in hindsight I would go with perennials by themselves,” he says. “You just have to work the shortfall of income into your budget.”
However, the trial did reinforce the value of sowing a cereal in year one and perennials in year two. This strategy, which was incorporated into the trial after the first-year failure of one treatment, was certainly competitive in terms of gross margin by the end of the project (only $121/ha less than best twin-sown treatment). This outcome occurred despite the higher costs from an extra year of weed control, fertiliser and pesticide. It’s also worth noting that because this treatment was initially twin-sown, the wheat yield of four tonnes per hectare could have been higher.
“I had hoped to yield five to six tonnes of wheat, but sowing wheat with perennials meant we needed more weed control and the crop didn’t go in until late June,” Mr Omodei explains
This strategy also had the highest plant density of all treatments in December 2016.
Another disadvantage of twin-sowing is that lower seeding rates were used for the perennials to ensure there wasn’t a significant yield penalty on the grain. But many growers prefer to double recommended seeding rates to give small-seeded perennials a competitive advantage over weeds.
These results demonstrate that establishing a cereal crop in year one and perennial pasture in year two is an attractive option. This strategy has a strong focus on the crop in year one (nutrition, timing, weed control) and can more easily incorporate grazing of cereals, something that proved too risky to attempt in twin-sown plots when perennials were establishing.
Not only has the trial confirmed the effectiveness of sowing perennials after a cereal crop, it has also provided some valuable observations about the individual species. Phalaris performed poorly in a mix, with some in the group commenting that it can be outcompeted if there is grazing pressure at the wrong time. Lucerne performed better without irrigation than some farmers expected, and chicory was considered “incredibly resilient” once it was established. Both chicory and lucerne also showed significant natural recruitment over the summer periods.
The performance of lucerne and chicory is likely to be a response to resting the paddock after grazing. Mr Rose believes rotating stock in and out of the paddock has been important for their persistence.
“I think you need to have two or three patches (of perennials) so you can get a rotation going, and maybe a bit bigger (than the two hectare trial area).”
The fact that perennials have persisted despite a significant germination of clover and annual ryegrass in year two has encouraged the group, who believe that having a strong perennial grass with annual ryegrass and clover coming back into the system is ideal.
“The thing to understand is that it’s not just perennials,” Mr Omodei says. “We’ll still have an annual part of the system to carry stocking rates in winter.”
Fitting perennial pastures on the farm
The benefit of having perennials in the system was highlighted by feed tests taken in November 2015. The results showed that perennial species maintained very high feed quality late into the growing season, despite a poor spring that year (Table 1). Notably, the phalaris displayed significantly higher crude protein than annual ryegrass, and chicory had the highest metabolisable energy (ME). The range of ME across all perennial species exceeded minimum requirements for all classes of sheep except early lactating ewes, and the crude protein content was high enough to meet minimum requirements for all classes of sheep, including weaners and lactating ewes.
But growing enough of this quality pasture is another cost. Mr Omodei points to modelling which suggests the full benefits of the system are seen when farmers have 20 to 30% of the farm in perennials. This is not only an additional factor for considering cost, but also relies on having enough land suitable for perennials.
“You need to know what parts of the landscape can handle perennials and that is the secret about working out how much land you allocate to them,” he says. “In Manjimup and the South West, they are more suited to areas with prolonged water at the end of the year. If you only have 10% of the farm suitable, you might still use that for flushing ewes or joining young stock, but you are not going to be able to put much weight on a young animal.”
Nevertheless, some in the group are more interested in doing small pockets around the farm that aren’t used for hay, and doing them properly. The benefit of this approach is that they can better manage risk by limiting costs, while making sure the perennials will persist well into the future.
For more on this trial, see the full report here and a video below.
For another perennial pasture case study in Manjimup, click here.
The project was supported by South West Catchments Council, through funding from the Australian Government’s National Landcare Program.