Farms & Farm Machinery #397

HORTICULTURE
fresh approach
One cucumber grower
saw a five-fold increase
in yield value per hectare
after taking on a practice
from grain-growers, and
new research from Hort
Innovation says the change
could transform the sector.
Anthony Wingard reports
Above: Ryegrass cover cropping led
to an increase in crop yield
Cover cropping is nothing new in the realm of agriculture.
But new research from grower-owned research and
development corporation Hort Innovation suggests that what
has been standard practice in grain production could lead to
fresh results for fruit and vegetable growers.
Cover cropping is the act of growing a crop for the soil, rather
than for harvest. In Australia, these crops might be barley or
ryegrass, legumes such as alfalfa or broadleaf plants such as
spinach.
These crops are allowed to grow to a point before being
mulched and reincorporated into the soil between the planting
and growing of harvest crops.
Horticulture, like most forms of farming, relies heavily on
healthy soils to maintain sustainable operations and the
increasing intensity and pressures of contemporary farming
has placed pressure on soil integrity to keep the $3.8 billion
vegetable market afloat.
In some ways, cover crops are enjoying a renaissance, with
farmers across Australia rediscovering just how beneficial
they can be – one grower saying “the advancements in cover
cropping have been the most advanced single change in
farming that I’ve seen in 30 years”.
For this reason, Hort Innovation supported a three-year
study by Applied Horticultural Research into cover cropping
in agriculture, assessing how the practice might improve soil
health and make vegetable growing more efficient.
The study found several benefits for the process, including
improvements to soil health and structure, controlling
of soilborne diseases, reducing the risk of erosion and
economically, provide a cost-effective alternative for farmers.
Looking at 14 different sites across six different states, the
study found the abundance of biology in the soil increased,
although results varied with regard to location, climate and
species of crop.
Research scientist with Applied Horticultural Research Kelvin
Montagu says cover crops will be highly beneficial to vegetable
growers.
“Cover crops were a forgotten practice which is now being
rediscovered,” he says.
“What you can see is around a 27 per cent increase in the size
or the abundance of soil biology. In terms of activity, we see
different enzymes plus CO2 and there is a 20 per cent increase
in activity [compared to tillage soil].”
The study indicated that two of the cover crops tested –
ryegrass and Caliente mustard – provided several benefits to the
soil over a long-term trial and also resulted in a slight increase
in yield.
Often, the best formula for cover cropping is a combination of
cover cropping and rolled crimper as opposed to single tillaging.
In one instance, the yield of cucumbers grown following
ryegrass cover cropping and without the use of herbicide
resulted in nearly 19 tonnes per hectare of cucumbers and a
gross income of $28,391/ha – compared to the same cucumber
crop planted in a tilled field which yielded just 4t/ha and
approximately $5,500/ha.
MG Farm Produce manager Darren Long says the change in
practice has paid off.
“With controlled traffic farming, cover cropping and minimum
tillage, we have seen our soil water infiltration and holding
capacity increase, the soil becomes less compacted and more
friable and yield increase, with plants showing more resilience to
weather extremes,” he says.
The benefits of cover cropping, it seems, aren’t just seen in
the improved yields and subsequent gross income for farmers
but also in the costs saved on fuel and machinery for tillaging,
Premium Fresh Tasmania farm manager Deon Gibson says.
“After crop covering, our horsepower, fuel and irrigation
requirements are all reduced and our soil isn’t as tight and
bashed down as we’re not trying to turn it into a plant crop in
the next day,” says Gibson.
“Your soil is a living organism, and you don’t want it to die, so
you want something growing in there and even if it’s a shortterm
cover crop you are still protecting it.
“Doing so in summer means you’re also not getting extremes
with a 30-degree sun hitting the bare soil,” he says.
After crop covering, our
horsepower, fuel and
irrigation requirements are
all reduced and our soil
isn’t as tight.
Above: Deon Gibson
Above: Kelvin Montagu
COVER CROPPING TIPS
Farmers opting to use cover crops should note different types
of cover crops perform better in different regions of Australia’s
varying climate.
To maximise the benefits of the crop and reduce potential
diseases, they should also consider whether cover crops are
suited to cool or warm seasons.
Ryegrass – a cool weather crop – is perhaps the most common
cover crop given its cheap price and the quick time it takes to
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