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Pasture

Sub clover: a valuable tool in dryland farm systems

B+LNZ investigates how sub clover can be managed to enhance productivity and profitability on dryland sheep and beef farms.
Tuesday, 29 November 2016

A resurgence of interest in subterranean clover has dryland farmers asking how best to manage and optimise production of both endemic and introduced varieties.   

Simple changes to grazing management that allow subterranean clover plants to flourish can have a profound effect on stock performance within dryland farm systems.

An increasing number of sheep and beef farmers are discovering this, as they use the winter-active annual clover to provide high quality, production-driving feed over early spring. 

Thanks to aerial applications of sub clover seed 40-50 years ago, the plant is endemic in New Zealand’s dryland hill country. But, over the years, poor management practices – including over-grazing and not allowing the plant to set-seed – have compromised its productive potential.

The role of sub clover 

Now, many dryland sheep and beef farmers are asking how they can manage and augment existing plant populations within their farm systems. To provide answers, the Sustainable Farming Fund’s Sub4Spring programme has been established. 

Trial sites stretch from Omarama in South Canterbury through to steep hill country near Gisborne. This geographical and climatic spread is allowing scientists, led by Lincoln University’s Professor Derrick Moot, and agronomists to determine best management practices for both endemic and introduced sub clover species across different environments.

Derrick says that, while sub clover has a role to play in many dryland farm systems, exactly what and where that role is, depends on the environment.

Preferring open swards, sub clover performs best on north or west facing slopes that open up and provide areas of bare ground in summer. If farmers can see volunteer annual clovers within the existing vegetation, it is a good indication that sub will perform well within that environment. This was the case for Wairoa farmers Dave Read and Judy Bogaard.

Not typical “sub” country

The couple own Waiau Station – 1200ha of unrelentingly steep hill country, upon which they run 10,000 stock units at a 60:40 cattle to sheep ratio. With a rainfall of over 1100mm, the farm would not be considered typical “sub” country, but the steep terrain – coupled with the intensity of the rainfall – means in many areas, moisture doesn’t penetrate the soil. 

Dave says he begun to realise the potential of sub clover five years ago, when it was identified on a north face of a rats tail-dominated cattle block.

Not knowing what it was, Dave had been admiring this patch of clover, proliferating next to an old erosion scar. For 12 years, the block had only been grazed by cattle and the plant had regenerated. (Left unchecked, sheep will eat it to ground.) Once it had been identified as Mt Barker sub clover, the couple sought expert advice on how best to manage and utilise it over the areas of farm where it was present.

They identified 10 paddocks with the highest proportion of steep north facing country and now actively manage these blocks to build the sub clover population.

Managing sub-clover

Changing management to allow the clover to set-seed has paid dividends. It is now driving September-to-November growth rates of 750-1kg/day in yearling cattle – and on very steep country.

In a normal winter, Dave and Judy will see the sub start to come away in July and August and they will set-stock dry cattle on this high-quality feed in August. 

“If we work with it and learn what it needs, we can use sub clover to benefit stock.”

For Dave and Judy, tweaking their management systems to encourage sub clover has allowed them to make low-cost production gains. They have also found over-sowing sub seed to augment the resident populations successful, although it did prove challenging this year.

Mixing it up

The block the couple chose for over-sowing contained very little resident sub clover. In December 2015, they shut the block up and allowed the existing vegetation to get rank. In March, they strip grazed the block with 200 recently-weaned R2 and R3 cows and, on March 23, used a fiddle (a hand-held seeder) to sow a mix of sub clover varieties at around 10kg/ha. 

The mix was designed to allow different varieties to perform within different micro-climates on the hill. Once the seed was sown, sheep were scheduled to run over the block for “soil to seed” contact, but the weather was too hot. In future, seed will be sown the day before the cattle go onto the break, so the animals trample the seed into the soil, while also removing the competing vegetation.

Early April rain resulted in a fantastic germination, but lack of any follow-up rain until late July appeared to decimate the seedlings.

Dave admits to feeling despondent – but, come spring, the sub clover came away and was flourishing by early November. 

While aerially over-sowing the sub seed is an option, Dave is happy with the more strategic approach allowing him to target dry, open faces. Sub clover cannot compete with white clover or rank vegetation on moist areas on his farm so managing competing vegetation is a critical part of the sub clover’s management requirements.