Agrichar trialled in field at Wollongbar
After very successful pot trials, Wollongbar Agricultural Institute researchers are undertaking field trials to assess the value of agrichar on iron-rich ferrosols.
Agrichar is organic matter that has been burnt very slowly with little oxygen present, a process known as pyrolysis.
In the pot trials earlier this year, research scientist, Lukas Van Zwieten, found charred paper mill waste applied at a rate of 10 tonnes per hectare raised the soil pH by one unit, making the soil 10 times less acid.
The agrichar application also eliminated plant-available aluminium which is toxic to some agricultural crops at low levels.
“The success of the pot trials encouraged us to do field trials,” Dr Van Zwieten said.
“In November we set up 36 replicated plots to investigate the benefits of agrichar and lime on ferrosols.
“This time the agrichar is made from charred chicken and feedlot manure.
“We applied it at a rate of 20t/ha and incorporated it by rotary-hoeing to 15 centimetres.
“While it is extremely easy to spread because it is so light, we are looking at ways of improving its handling and marketability.
“We have planted a peanut ground cover, arachnis pintoi, where we will measure crop yields and hope to have results in early 2007.
“One of our main goals is to quantify carbon sequestration in soil.
“Agrichar has the potential to reverse 150 years of organic matter decline in Australian soils.
“Results so far have been stunning.
“We will also measure the nutrient content of the agrichar, particularly calcium and magnesium, its cation exchange capacity, pH and changes to microbial activity and microbial biomass.”
The agrichar research team has established a method for greenhouse gas analysis to examine emissions from soils.
“Basically, we want to see if we can reduce the formation of nitrous oxides which develop following fertiliser application,” Dr Van Zwieten said.
“We suspect agrichar may help bind the nitrogen into the soil, reducing the biological reactions that cause loss of nitrogen.
“Char itself has a high fertiliser value, depending on its source.
“We want to know how much nutrient in char is available to plants.”
The Wollongbar field trials will provide information for a similar trial in central Vietnam next year to build soil health and provide forage crops as part of an ACIAR aid project.
The trials will complement Best Energy Australia’s US work in charring dairy and beef feedlot wastes.
There they are harnessing the energy generated by the pyrolysis process to dry the effluent before it is pyrolised and spread on soil.
Results of the Wollongbar trials will be announced at an international agrichar initiative conference at Terrigal in April.
Dr Van Zwieten is on the organising committee for this conference (website: www.iaiconference.org).
Contact the NSW DPI Environmental and Agricultural Health team.