Method of Applying Biochar in Avocado Farming

Biochar was applied at 5%, 10% and 20% (volume basis calculated on a depth of 500 mm). The biochar was applied in two applications. The first half was applied at a depth of 500 mm and a 250 mm layer of subsoil placed on the biochar which was incorporated with a rotary hoe. This process was repeated with the second half of the biochar applied and the topsoil replaced on top, followed by rotary hoeing.

Two rows of 36 trees were planted, with each tree planted 4.5 m apart and each row 9 m apart. The first row was the control, and the second row contained the biochar.

Trees were planted in early December 2014, all with the same under tree fertiliser mix. . Trees were also mulched with a mixture of chicken litter, hardwood sawdust and wood chips. Both the biochar and control rows were on the same line for irrigation and had exactly the same water allowance.

Results

From the visual and measured observations, trees planted with biochar had 18–26% greater growth rates than the control with no difference between the various application rates of biochar. Fruit yield however, gave a different result. The 5% and 20% of treatments give significantly more fruit on average than the control and the 10% treatment. This indicates that there could be different interactions between the biochar, soil mineral and organic matter, added fertiliser in the 10% treatment than in the other two treatments which could partly account for the lower yield.

Economic Benefits

The study indicated that there was a net benefit of US$105 for every tonne of biochar applied and the average net profit per tree was US$35.

This farmer designed trial has demonstrated that biochar can significantly improve the growth of avocado seedlings and increase fruit yield. This is an important study and crucial to development of the biochar industry in Australia. It provides evidence that biochar has environmental and economic benefits to the farming and horticultural sectors. Read more about biochar boosts yields in Avocado farming.

Drivers

Firstly, we were engaged by Chandala Poultry to design a system that would recover the energy from chicken litter the farm produces and use it to meet the farms energy requirements. We did look at other bioenergy technologies including anaerobic digestion but decided, after consultation with the owner, on pyrolysis.

Secondly, technologies to produce biochar in Australia are either too big, needing thousands of tonnes of feedstock to be viable and a very high capital expenditure or the smaller, cheaper technologies, a little underdeveloped.

The final and key driver to start building a biochar kiln was that we wanted to demonstrate bioenergy technology to farmers. We believe that bioenergy and the valuable byproducts produced by the process complements agriculture and closes the nutrient loop. Most farmers have not had the opportunity to visit a bioenergy plant so we decided to bring bioenergy to farmers.

Beginning the process

After making the decision to begin building a biochar kiln, we sourced a design that would meet our requirements:

• Simple and user friendly
• Affordable
• Continuous flow
• Able to be made mobile for demonstration purposes.

We then contacted various Geraldton based (trying to keep it local) firms capable of building a biochar kiln and asked them to quote on materials and some construction work. It was our aim to get the components built and do most of the construction of the biochar kiln ourselves, this way we get to know the machine inside and out.

In the beginning of 2013 we started building the biochar kiln and after some testing quickly found a few issues that needed to be addressed. These included:

Maintaining heat

It is critical to be able to maintain heat inside the biochar kiln for the pyrolysis process to take place. In the beginning, we used minimal insulation and because of this we were losing a lot of process heat. After we addressed this problem we were able to get to operating temperature quickly and maintain the temperature where it was needed, inside the pyrolysis chamber.

Gas vs diesel

Initially we were using LPG gas to heat the biochar kiln however, after looking at the issues and regulations associated with using gas, we decided to use a burner fired on diesel to provide the heat needed to get the process going. We find it easier to manage logistically, just as efficient and a lot safer to operate.

Course material

As we are using augers to move the feedstock into and through the biochar kiln, unless it is ground quite fine we can have some issues, the longer pieces wrap around the auger shafts and can block the auger. This necessitated purchasing a tub grinder which we will use to grind organic materials like wheat straw and wood chips.

Moisture content

Feedstock moisture content is also very important. If the moisture is too high then the process does not work and we have to use a lot of energy just to dry the material to a point when it will char. This is inefficient and not what we are trying to achieve. The ideal environment for the biochar kiln is to use an external heat source to heat the chamber then be able to turn it off and rely on the incoming material to provide the energy necessary to maintain the process, this is renewable energy.

This particular problem meant we had to come up with a way to dry the material before we processed it. After long debate we designed and engineered an internal drying system. The dryer is an auger we have installed inside the kiln above the pyrolysis zone. We load the material via a loading auger which feeds into the dryer where it moves along very slowly. The moisture is driven off by the heat produced by the biochar kiln as it moves through the dryer.When it reaches the end of the drying auger the material drops out into the pyrolysis auger.

This auger completes the biochar process, gases bound up n the material are released as the material turns to biochar. These gases are then combusted in the gasification zone to create heat.

Where are we now?

Since the upgrade last month we have run the kiln a few times but like anything new, we have had a few teething problems. Namely, with heat expansion and some manufacturing issues with the drying auger. We believe we have sorted out these issues and are looking forward to testing the process again soon.

Stay tuned for updates or contact us to learn more.

The Anaerobic digestion process or AD for short uses micro-organisms to break down organic materials in the absence of oxygen to produce biogas and bioenergy.

Stages of anaerobic digestion

• Hydrolysis – where the organic material is mixed with water and broken down into soluble organic molecules
• Fermentation – where acidogenic bacteria, yeasts and mould convert the molecules into volatile fatty acids (VFA’s)
• Acetogenesis – Acetogens then produce acetic acid, carbon dioxide, ammonia and hydrogen from the VFA’s
• Methanogenesis – methanogens produce methane and carbon dioxide

The Anaerobic Digestion Process

What is biogas?

Biogas is a gas comprised mainly of methane. Methane is highly combustible and can be used for heating, cooling and electrical generation. See below for typical composition of biogas.

• Methane – 50-75%
• Carbon Dioxide – 25-50%
• Nitrogen – 0-10%
• Hydrogen – 0-1%
• Hydrogen Sulphide – 0-3%
• Oxygen – 0-2%

Digestate

Digestate is the by-product of the anaerobic digestion process and is rich in nutrients. Digestate is relatively easy to handle and can be used as a soil conditioner and depending on the nutrient value of the feedstock, used to replace mineral fertilisers.

Conditions for Anaerobic Digestion

Micro-organisms and bacteria involved in the anaerobic digestion process can operate over a wide range of temperatures and conditions however there are some important factors that are important for the anaerobic digestion process to take place.

Temperature

Anaerobic digestion bacteria can be broken down into two main types:

• Mesophilic bacteria  – prefer to operate between 20°C and 45°C. Solids content is around 15% and the residence time usually 60-90 days and;
• Thermophilic bacteria – operate at higher temperatures >50°C. Solid content is greater at 20% – 45 % and residence time from 9-45 days

Mesophilic digestion is a more simple method and relies on ambient temperature whereas thermophilic digestion requires the addition of heat. Thermophilic digestion is much more management intensive and the organisms are a lot more sensitive to temperature change. Ideally, micro-organisms prefer to be maintained at an even temperature throughout the year whatever the process.

pH

The ideal PH for anaerobic digestion to take place is 6.8 to 8.5 however as the anaerobic digestion process takes place, the acidity of the substrate (feedstock) increases due to the increase of organic acids, especially in the early stages of the process.

As the process develops more methanogens will be produced and raise the PH however, it needs to be monitored. If the substrate is allowed to become to acid or alkaline the performance of the micro-organisms will decline to a point where methane production stops.

An Oxygen Free Environment

“Anaerobic” is from a Greek word meaning “living without air” and anaerobic organisms will die if oxygen is allowed into the system. Gas tight conditions are essential for anaerobic digestion to take place.

Anaerobic Digestion Reactors

There are three main types of anaerobic digestion reactors.

Complete Mix

Complete mixed digester vessels are insulated and maintained at a constant elevated temperature in the mesophilic or thermophilic range and suitable for wastes with 3-10% solids.

The digester is usually comprised of an insulated tank with mixing and heating ability. A gas tight cover is used to trap the methane or the gas is piped to a storage area. Waste heat can be used to heat water that is circulated throughout the tank in most situations reducing the retention time.

Plug Flow

Plug-flow digesters are a long, rectangular container, often built below-grade, with an airtight, expandable cover. They are suitable for ruminant animal manure with a solids concentration of 10% to 15%.

Plug flow digesters have a waste collection system, an area to mix the manure with water and the digester itself. As material is added to one end of the digester it pushes older manure toward the end of the tank. The gas is captured by the expandable cover. A plug-flow digester requires minimal maintenance.

Covered Lagoons

A covered lagoon anaerobic digester is basically a hole in the ground lined with plastic sheeting that acts as a manure storage area and an airtight cover.  The cover traps methane gas produced during decomposition of the manure and a suction pipe extracts the gas for use.

Covered lagoons are a very simple method for recovering energy from manures; they have a low capital cost however they are not very efficient and not suitable for colder environments

Benefits of anaerobic digestion

• Greenhouse gas emission reduction
• Carbon farming
• Energy production
• Fertiliser value of digestate
• Replaces fossil based energy
• Odour suppression
• Vector control
• Weed and pathogen control

We recently attended a biochar workshop held in Elmore Victoria, Australia. The 2 day event run by the Kyneton Transition Hub and Bendigo Sustainability Group attracted a diverse crowd with a range of experience in the production and use of biochar.

Dr Stephen Joseph and Dr Paul Taylor ran proceedings and shared their knowledge. Attendees were treated to some of the latest findings in biochar research as well as some “hands on” practical experience in the making of biochar mixes, types of kilns and ways to make biochar, end uses and the benefits of biochar as a soil conditioner/fertiliser.

Biochar is an interesting topic in Australia, the benefits have not been proven to mainstream agriculture as yet and until it is, biochar wont be taken seriously. So far, it’s been the increasing number of small producers and groups like Kyneton and Bendigo that have been spreading the word and sharing the knowledge.

I must give my thanks to the organisers of this event. The hospitality shown was awesome, there was great food and plenty of it, good company (and a couple of beers) around the campfire on the Sat night and a warm swag and tent to keep the Elmore chill out during the night. Thanks very much guys!

I think its great to see the variety of projects and it’s the first real step to getting farmers and the rest of Australia away from their reliance of fossil based products and toward more sustainable agricultural systems.

Overall 117 projects shared 72 million dollars with research including reducing emissions from livestock and cropping, through to on–farm trials of practices and technologies to help land managers become more resilient to a changing climate. Let’s face it, this is the big investment in agriculture and will ensure its sustainability into the future.

The bad press and the resentment of the “carbon tax” (actually, it’s not a tax, it’s a floor price for a market based mechanism) comes from a lack of understanding of the reasons behind why we really do need a price on carbon.

Sure, climate change is seen as the main driver and this is true, we can’t continue to pollute the environment without incurring some cost to the very way we live our lives. However, the main reason we need a price on carbon is to reduce our dependence on fossil based energy and the products that flow from it, such as fertiliser chemicals, fuels and oils.

Pricing carbon begins the transition away from this source, as the price on carbon makes fossil based energy and products less attractive, investment will flow to more sustainable sources. For farmers, this means a range of alternative farming practices will become more attractive and others will become involved in other industries, such as bioenergy, where farmer groups can team together, form grower owned cooperatives and use their crop residues to fire local bioenergy plants producing bioenergy, biofuels and biochar.

Research projects like, Filling the Gap and Action on the Ground take it another step further by investing in projects that will benefit the environment and potentially put a dollar into the back pocket of Australian farmers.

For more information on the funding outcomes checkout DAFF’s Carbon Farming Futures website and see for yourself, the amount and variety of work being done in this area.

As part of Energy Farmers Australia’s vision to see biochar integrated in Australian farming systems, we are looking at the options to get biochar back into the soil in Australian agricultural systems.

Biochar is hard to handle, it can be powdery in which case it does not spread well. It also takes a lot of processing to get it into a form (granulation and pelletising) that can utilise farmers existing equipment.

While char does not spread well, it will be an option in broad acre cropping systems where farmers are using mouldboard ploughs to reduce the impact of non wetting sands and resistant weeds. Spreading the char and then ploughing will bury the char up to 400mm underground and looks to be a very simple yet effective way to incorporate the biochar through an existing operation. Spreading and ploughing will work well on sandy soils however will not be applicable on soils that mouldboard ploughs cannot be used. So we need to look at other options.

We have teamed up with Wayne Phillips and his new machine the New Horizon Subsoiler Extruder. Subsoiling involves adding a medium (e.g. water) to biomass, in this case char and deep banding it into the soil. The subsoiler can handle a range of biomass from manures to straw and will open up myriad of opportunities to blend char with different feedstocks, potentially offering an alternative to traditional fertilisers.

While the subsoiler is still in development stage we are very excited about its potential. We will be trialling the subsoiler this season with biochar and other forms of biomass.

Here’s a sneak peak of what it can do, stay tuned for updates.

http://youtu.be/A2l57g44sxU

Reforestation and afforestation

This methodology proposal involves the reforestation of cleared land and afforestation on land where no forests previously existed in order to sequester carbon.

• The project activity involves establishing trees through direct means, such as hand-planting seedlings, machine-planting seedlings, or direct seeding
• The project activity occurs on lands that were clear of non-project trees for at least the five years preceding commencement and no non-project trees are removed in order to undertake the project activity
• Can be comprised of a single tree species, or a mix of tree species
• Trees within the project area cannot be harvested

Native Forest Protection

This methodology applies to the establishment of projects to protect native forests through the prevention of clearing and clear-felling harvesting activities.

The establishment of native forest protection projects is intended to prevent the emissions generated through business-as-usual logging practises, and to maintain and enhance the carbon stocks in native forests. Such projects have the additional benefits of enhancing local biodiversity, diversifying landowners’ income and maintaining aesthetic and recreational values of the forest.

Continue reading.

We travelled to Dale Park’s property just south of Badgingarra in the Northen Ag Region of Western Australia (WA) on Friday the 25th to lend a hand to Dale, Paul Blackwell from DAFWA and Dave Gartner from AG Lime WA to lay down the West Midlands Group’s first biochar trial under the Northern Agriculutral Catchments Council (NACC) Sustainable Farming grant.

This trial is looking at annual pasture response with an application of 2 different biochar with and without lime. The group also plans to run similar trials this year looking a responses from biochar applications in cropping systems in WA.

While Energy Farmers have no direct involvement into this project we are very much encouraged that work on biochar is being carried out and we see the integration of biochar into WA pasture and cropping systems as being a positive thing for agriculture.

For more information on the project and biochar in WA contact the West Midlands Group, Paul Blackwell from the DAFF office in Geraldton or visit our biochar page.

Here are a few photos of the day.

The Government has taken industry views into account in making regulations for:

• the Australian National Registry of Emission Units which will support both the Carbon Farming Initiative and the carbon pricing mechanism;
• An initial list of activities which will be eligible under the CFI once technical methodologies are developed;
• The protections against adverse impacts on water resources, biodiversity and local communities;

Application forms are available on the DCCEE website for potential participants to:

• become a ‘recognised offsets entity’
• open an account in the Australian National Registry of Emissions Units

For more information on the CFI and methodologies currently under development see the DCCEE’s website

The Department of Agriculture Fisheries and Food have launched “Filling the Research Gap” as part of its Carbon Farming Futures Program. 201 million dollars will be invested to support research into emerging abatement technologies, strategies and innovative management practices that reduce greenhouse gas emissions from the land sector, sequester carbon and enhance sustainable agricultural practices.

The funding is available to Australian companies, business, research organisation, government agencies and departments. Research priorities for funding round one of the Filling the Research Gap program are:

• reducing methane emissions
• reducing nitrous oxide emissions
• increasing soil carbon
• improved modelling capability.

This is a good opportunity for the Ag sector to investigate ways to better manage our emissions and ultimatley profit from doing so.