Download Sutton Landcare Soils Workshop Saturday 9 October 2010

RECORD OF MEETING
Sutton Landcare Soils Workshop
On Saturday 9 October 2010, David and Jane Vincent hosted a soils workshop at their
property Gollion. The chief presenter was Dr Maarten Stapper.
Dr Stapper gave a broad-ranging introductory session on soil chemistry and soil
characteristics in the local region. Some points included:
. When discussing carbon levels in soil, it is important to differentiate between pure carbon
and carbon in chemical compounds (such as in carbonates and in organic compounds made
up of carbon chains). For discussion purposes here, roughly half of the carbon in chemical
compounds is regarded as pure carbon.
. Before the arrival of white men to Australia, the pure carbon level in soils was thought to
be around 6%. Now it is around 1% and needs to be at least 2% for a soil to be deemed
healthy.
. Healthy soil contains 15-20 thousand microbial species, 95% of which are “beneficial”.
Amongst other things, they coat the roots of plants and protect them from attack. Plants need
calcium to grow strong cell walls, but can’t absorb calcium directly – the nematodes and
fungi on the roots perform this action. Compost teas boost the microbial population.
. Nitrogen and phosphorus- rich fertilizers are unnatural – plants thrive on these simple
water-soluble compounds but don’t get the chance to take up minerals needed for strong cell
walls. By comparison, long carbon-chain molecules (such as sugars) manufactured via soilborne microbes allow scope for the absorption of important minerals. Insects such as locusts
find it difficult to digest complex long-chain compounds, so they tend to avoid wellmineralised plants. Such plants also contain relatively less water and are therefore less prone
to frost damage.
. Highly-compacted soil is to be avoided. Amongst other things, root-eating nematodes can
live in compacted soil but their predators cannot. Also when roots reach a compacted layer
they tend to grow sideways instead of downwards. (Dr Stapper demonstrated the use of a
hydraulic penetrometer to establish the limits of a viable root zone).
. Weeds are relatively primitive plants. Cape weed can grow in compacted and calciumdepleted soils. Patterson’s Curse thrives in copper-deficient soil. One benefit of such weeds
is that they pump carbon into the soil and their roots establish channels. Eventually this
should assist paddock grasses to flourish and crowd the weeds out.
. Single superphosphate pellets are quite acidic and active fungi nearby tend to be killed off.
Many plants can tolerate some fertilizing because healthy root tips exude sugars that shield
the roots from the low pH soil nearby. However applying superphosphate regularly is not a
good long-term option.
Dr Stapper also discussed the long-term negative aspects of genetically-modified cropping,
and the current wide use of antibiotics in the raising of poultry, beef cattle, lambs and fish
farming.
After morning tea, David Vincent gave a presentation on making dry compost and compost
tea. He demonstrated his system for making compost out of a mix of shredded tree lucerne,
brown plant waste including shredded paper, rock dust, seaweed, animal manures and water.
In fact, any product of a previously living thing can be composted.
Good compost is black and smells sweet. His compost tea apparatus consists of a large
vessel of water containing a mix of compost, worm juice, fish hydrolysate and liquid seaweed
with a large air pump to aerate the mixture. The microorganisms in the compost are leached
out into the water and multiply by feeding on the nutrients in the fish hydrolysate and
seaweed. He applies the resultant compost tea to the paddocks using a boomless sprayer. It is
not necessary to cover all of the paddocks because the microbial action spreads naturally. It
may take 3-4 years for the beneficial effects to be noticeable.
David noted that worm juice is a good first additive to compost tea, as well as being a useful
fertilizer when applied directly to the soil.
Dr Stapper noted that a new biological product called TM21 is a good bio-stimulant that
feeds and increases the population of beneficial micro-organisms in soil.
The group then walked through nearby paddocks to check the sugar content of grasses treated
with compost tea and a control area with no treatment. Testing involved crushing leaf
samples in a manual garlic crusher then testing the resulting liquid with a hand-held
refractometer (Brix meter). The higher the Brix reading the higher the sugar and mineral
content of the plant, the more healthy and productive it is and the greater its resistance to
insect attack and frost damage.
David also showed his worm farm, which uses virtually any food scraps apart from onions or
citrus. The worm castings and worm juice extracted are valuable sources of microbial food
for any plant.
The attendees expressed their gratitude for Dr Stapper’s presentations and to David and Jane
for hosting the workshop and sharing their considerable experience with compost and
compost tea production.
23 Landcare members attended the workshop:
Alan McNeill