Posts Tagged ‘ lettuce ’

Breakthrough technology improves lettuce harvest yields

BiOWiSH™, a breakthrough enzyme technology, has boosted hydroponic lettuce weights by up to 30% at harvest time, according to results of a recent trial. The new technology was adopted during multiple full growing cycles at the Glenorie Hydroponics lettuce farm in New South Wales. The results showed BiOWiSH™ treated lettuce were 17% to 30% heavier at harvest time for red and green butter lettuce varieties, respectively.

BiOWiSH™ is a natural soil ameliorant and water treatment that provides an optimum environment for plant development and growth. Through the action of a proprietary group of enzymes and co-factors, BiOWiSH™ enhances the availability of nutrients, producing healthier, more vibrant and stronger plants.

Joe D’anastasi, owner of Glenorie Hydroponics, said the technology will revolutionise the industry by helping farmers to harvest more regularly.

“I have been in the hydroponics business for 23 years and I haven’t seen anything like it before.”

“We introduced the technology in one of our worst performing greenhouses, to really test it out, but within weeks it became one of our best in terms of plant performance and health.

Not only were the lettuces heavier, they were also thicker and more consistent,” he said.

According to BiOWiSH Technologies Sales and Marketing Manager, Cameron Burgess, the technology also prevents problematic sludge build-up and algae accumulation in irrigation channels by accelerating the breakdown of organic wastes into its final inert compounds.

Mr Burgess added that the potential impacts of the technology on a global scale are huge.

“Food production needs to triple in the next 50 years to feed a rapidly growing global population. It is exciting to think what our technology can do to help address looming food shortages worldwide,” he said.

BiOWiSH Technologies owns exclusive rights to BiOWiSH™. The company has adapted the technology for the hydroponics market by developing a powder product called BiOWiSH™-Crop, which is added to irrigation tanks as part of a hydroponics farm’s nutrient system.

BiOWiSH™-Crop is distributed locally by Accent Hydroponics. To download the complete Glenorie Hydroponics case study, go to the company website.

For further information contact:
Lorenzo Gella,
BiOWiSH Technologies

Issue 108: Intelligent Farm Management – Ghost Gully Produce

September/October 2009
By Steven Carruthers

Water restrictions and farm management issues have driven many growers to water-saving technology to ensure their operations are resource and cost effective. Ghost Gully Produce is an example of this technology playing a key role in intelligent farm management.

Seedlings are grown by the grower’s mother-in-law.

Ghost Gully grow seven lettuce varieties – red and green corals, oaks, minuettes and baby cos.

Farm infrastructure includes sand filters and a mist cooling system.

Gary and Kym Samuelsen.

Located in Gatton, Ghost Gully Produce is one of a handful of small family-owned hydroponic farms in the Lockyer Valley, in South East Queensland. Gary Samuelsen, a former dairy farmer, turned to hydroponic lettuce and herb production not long after the dairy industry deregulated. Seven years ago the family purchased a run-down 18 ha nursery, mostly scrub, with four small greenhouse structures (20m wide x 75m long). Gary replaced the plastic roofing with hail net and adapted the existing benching infrastructure to an NFT growing system using half-round stormwater pipes with soft plastic covers and slits to accommodate seedling plugs.

New infrastructure includes five growing systems under hail net.

The retrofit greenhouse structures have open-sides and hail net roofing.

“That got us started,” said Gary, “and then we met Joe who formulated our nutrient and introduced us to proper channel with clip-on lids.”

Joe Crane is a specialist consultant in the region with over a decade of experience in nutrient formulation, hydroponic system analyses and design, and farm automation, including cold room temperature logging. The collaboration has resulted in new farm infrastructure, including washing, packing and cooling sheds, five new NFT growing systems under 1 ha of hail net, Black Max ozone water disinfection equipment, and a WiSA water management system.

Water Management System
The Australian-developed WiSA system was primarily designed as an irrigation system for field farming to enable precise control of water and nutrient applications. The system is connected to a dedicated PC 24/7 to get the optimum data and utilisation of equipment. Following a number of below average rainfall years and severe water restrictions in South East Queensland, Joe took it upon himself to redesign the system for hydroponics. WiSA was so impressed the Victorian-based company appointed Joe its Queensland distributor, and Ghost Gully Produce became the first hydroponic farm to adopt WiSA water-saving technology.

“Stage 4 water restrictions meant we had to reduce water usage by 25%,” explained Joe. “The WiSA system allowed us to attain 33.3% water saving,” he added.

When Gary first started the business he used town water but was beset with problems including Pythium and occasionally over-chlorination. Today, he uses a combination of town and dam water and ozone disinfection.

The farm operates six large storage tanks, each holding 95,000 litres.

Aquatic weeds minimise water evaporation.

From the dam, the catchment water is pumped into three large storage tanks (95,000L each) where it is treated with Sporekill to reduce the pathogen load. When required, the water is transferred to duplicate upper level storage tanks with in-line ozone (O3) injection to ensure the water is free of pathogens. The upper storage tanks supply clean water pumped to eight growing systems on the property.

Dam water is first treated with Sporekill to reduce the pathogen load.

Each growing system has its own dedicated reservoir tank (10,000L), dosing equipment and ozone generator. In total, the farm operates 14 Black Max ozone generators at strategic points throughout the water system to prevent water-borne diseases.

The WiSA system works in real-time, that is, what is happening now, not last week. Variable factors such as water usage, farm tank levels, system pressures, nutrient conductivity, pH, temperature (air and water), humidity, rainfall, nutrient dosing times and valve timing are monitored and logged by the WiSA system.

Joe Crane explains the WiSA system with automatic nutrient dosing.

Sensors monitor air temperature and humidity.

“These variables are the basis for automated decision-making on the farm, and can be graphed and recalled individually and comparatively over time periods for farm management decisions,” explains Joe.

The WiSA system manages variables in real time.

The level of monitoring also extends to the washing shed and cold-room where sensors record temperature in 30-second increments.

“In the event of a dispute over cold-chain management, we’ve got the records,” said Joe.

An interesting aspect of the WiSA management system is nutrient management. By analysing the conductivity factor and water temperature of the nutrient reservoir, the conductivity can be adjusted according to water temperature on a floating scale. Nutrient is added to increase CF via automated dosing pumps, and CF is decreased through plant usage.

“The computer scales the nutrient formulation for us,” explains Joe. “Most of the time we run so long that we only dump when it rains,” he added.

The farm’s nutrient formulation process is proprietary to Joe’s consultancy business, Cyber-Hydroponics, with nutrient formulations uniquely tailored to suit water supply, individual crops, and to account for seasonal variations in temperature. Farm formulations are prepared by the farmer, offering a cost saving over conventional nutrients.

At first, the use of multiple Black Max ozone generators (BM2s) at different points in the water system seems excessive.

Gary Davies from Black Max explains the ozone injection system.

“The farm is spread over a large area and it was more practical to use multiple units,” explains Gary Davies, principal of Adelaide-based Black Max Ozone Generators. “A smaller, centralised farm would not require as many units” he said.

The Australian-made Black Max ozone generator was first introduced to the hydroponics industry in the late 1990s, at a time when many growers were unaware of the benefits of using ozone, or O3, to disinfect water. It is one of the most effective bactericides known to science. On the oxidation chart it is listed above chlorine, iodine and bromine, but unlike these chemical options for disinfection, ozone dissolved in water breaks down to oxygen in 15-20 minutes, leaving no chemical residues.

Ozone generators are linked to disinfect dam water.

System reservoirs are coated with insulation to keep temperatures warmer during winter and cooler in summer.

Ghost Gully uses the BM2 unit, which produces 2.6mg of ozone/litre of air for treatment of reservoirs up to 10,000 litres. Black Max also makes the smaller BM1 that produces 0.6mg of ozone/litre of air, for treatment of any size reservoirs up to 2,000 litres. Housed in marine grade aluminium casings, the BM1 and BM2 use a high quality ozone-producing UV lamp operating at a precise wavelength. The units have a small see-through window to easily and quickly check lamp operation. Ozone is introduced in-line using the ‘venturi’ principle, a vacuum effect caused by a reduction in fluid pressure that results when a fluid flows through a constricted section of pipe.

Both the grower and Joe are convinced about the effectiveness of ozone. Joe recalls an incident when an ozone lamp failed and a pathogen problem became evident in one section of the farm.

“Gary called me the next day about a problem on the farm, something we hadn’t seen for a long time,” recounts Joe. “We quickly worked out that an ozone lamp had failed after several years’ use. We put a spare unit onto the system and the problem quickly disappeared.

“There is no doubt in our minds about the effectiveness of the ozone system in pathogen control.”

Ozone is also used in the washing water to remove bacteria, fungi and moulds, and is said to extend the shelf-life of produce. Trials at Ghost Gully Produce point to a 3-week shelf life once lettuce leaves the cold-room.

Harvesting is made easier using a re-engineered ground lettuce harvester.

Ozone bubbles through the washing water.

Higher yields, quality and longer shelf-life are attributed to ozone treatment.

“They just last longer,” said Gary Samuelsen.

The longer shelf-life could also be partly attributed to a twice-weekly foliar spray of SilikaMajic, a potassium silicate-based product from Flairform (

“It’s got to be a good thing,” said the grower. “It promotes cell growth and slows down transpiration. In summer, lettuce stay good for an extra 2 days, longer than normal without it,” he added.

According to Joe, ozone is extremely effective at controlling water borne diseases such as Pythium.

“Pathogens are always there,” he explains, “but ozone keeps them under control.”

He added that pathogens are hardy and likely to harbour in irrigation lines.

“Most are eliminated when the return water reaches the system reservoir, which is ozonated 24/7,” he said.

“I recommend that all my consulting farms use the ozone sterilisation method. As well as being effective, the Black Max units are robust and have an excellent life.”

At under $1,000, the Black Max ozone generators are supplied with a fully assembled installation kit consisting of 3 metres of ozone hose, non-return valve and ozone jet (venturi). Accessories include a ‘maxizone’ injector that requires a minimum flow rate of 1,800 litres/hr and a ‘megazone’ injector manifold requiring a minimum flow rate of 9,000 litres/hr, to suit 1-2 hp pumps.

Final remarks
With an annual production capacity of over a million plants and plenty of room to expand, Ghost Gully continues to be a work in progress.

Water-saving practices start at the dam, which has been allowed to grow over with weed to minimise evaporation. It also eliminated the large duck population that once frequented the dam.

“If ducks can’t see the water, they won’t land,” quips the grower.

On-farm water-saving practices also include capturing overflow rainwater, referred to by the grower as “God’s nectar”, from the building structures and growing systems. All the system tanks have overflows that route excess water to a lower catchment tank (38,000L). When the water reaches a certain level it is pumped to the upper storage tanks.

But the heart of the operation is the WiSA water management system that allows produce to be turned over from seedling to market in a way that’s both resource and cost-effective. Recording variables such as water usage and storage and processing temperatures assists with the farm’s water efficiency program and Quality Assurance compliance.

Ghost Gully has shown that ozone disinfection is simple and efficient, with benefits including higher yields and quality and longer shelf-life, and no chemical residues. Where ozone disinfection was once cost-prohibitive for many small and larger growers alike, the Black Max ozone systems are affordable.

Ghost Gully Produce is a highly successful operation and a prime example of automation playing a key role in intelligent farm management.

For further information contact:
Gary Samuelsen
Ghost Gully Produce,
2 Rangeview Drive, Gatton Old 4343
Ph: 07 5462-5502
Fax: 07 5462-5504

Joe Crane
PO Box 3918, Burleigh Town, Qld 4220
Mob:0416 232 030
Fax: 07 3319-0926

Gary Davies
Black Max Ozone Systems,
PO Box 429, Noarlunga Centre, SA 5168
Ph: 08 8327-3150
Mob: 0408 825 511
Fax: 08 8327-3144

Graeme Wright
WiSA Irrigation Solutions,
PO Box 592, Echuca, Vic 3564
Ph: 03 5480-7713
Fax: 03 5482-3736

Issue 100: Wild Storm Shreds Lettuce

May/June – 2008
Author: Steven Carruthers

Wild storms and floods are a natural part of the Australian landscape but they bring with them devastating consequences including distress and disruption to business and livelihoods. STEVEN CARRUTHERS reports on recent extreme weather events in Queensland with a focus on risk management strategies for growers.

The weather bureau reported wind speeds of 150kph.

Open-air hydroponic lettuce and herb growers in south-east Queensland ducked for cover when a wild storm ripped through Harvey Bay, Maryborough, Childers and Bundaberg in early February 2008. Although the weather bureau reported winds of 150kph, estimates in the Childers region put the wind speed much higher. The violent wind snapped large gum trees, flattened fences, crushed NFT growing tables, and shredded crops. The only good news was the dams are overflowing.

Business partners Brian Ellis (left) and Dan Buckley inspect the crop damage.

The network of lettuce and salad growers under the ‘Clean Green’ label reported two hydroponic NFT farms severely damaged with crop losses of 75%, and two farms moderately damaged with a combined crop loss of 20%. The collective damage bill, including clean-up costs, was estimated at over $100,000. Although the growers had infrastructure insurance, they were not covered for clean-up costs or crop losses.

Fallen trees and flying vegetation caused much of the damage.

The wild storm brought with it hail and heavy rain, but it was the driving wind that snapped tree trunks, stripped branches and defoliated towering gum trees that caused much of the damage.

“The whole district was flattened, strewn with broken trees and native vegetation,” said Brian Ellis, the principal grower at Clean Green Hydro.

“It did quite a lot of damage to our farm including damage to fences, several growing tables, one shed, refrigerated vehicles, and it shredded 75% of our crop. The financial loss will be quite heavy, but we have a very solid business and we will survive and prosper,” he added.

Violent winds snapped gum trees that in turn crushed NFT tables.

Brian said that the damage could have been a lot worse. A bamboo windbreak planted along the front of the 5ha property acted as a wind shield to a degree. Additionally, the building structures are cyclone rated and survived the storm, except one shed that was damaged by a fallen gum tree. Unfortunately, the refrigerated vans were parked near large gum trees and there wasn’t enough time to move them. The damage was extensive.

The 5ha Clean Green operation was strewn with broken trees and native vegetation.

The propagation nursery was protected to a large extent by the pack shed nearby, which was cyclone rated. However, some of the growing tables were not so lucky and were crushed by fallen trees and branches. The wild wind also shredded the majority of the lettuce and salad crop on those tables left standing.

“With the storm travelling from north to south, the same direction as the tables, the damage wasn’t as bad as it could have been if the wind was travelling east-west,” commented business partner Dan Buckley.

While the district experienced a complete power failure, the Clean Green operation had purchased an automatic back-up power generator from Brisbane-based Genelite a few weeks before Christmas 2007.

Fortuitously, the generator had been calibrated by technicians only a few days before the storm struck, and it kicked in flawlessly within minutes of the power failure.

“The ‘gen’ equipment sensed the power failure and automatically switched the generator on to power the refrigeration shed, RO equipment, computers, pump sheds and lights. The main problems were keeping the tanks from overflowing and filters from clogging,” Dan said.

In a land frequently ravished by droughts and floods, Australian farmers are renowned for their resilience and hydroponic growers are no different. Typical of many rural farmers, Brian and Dan put a brave face on their loss.

“We can shut down and totally sterilise most of our salad systems,” Brian remarked. “This is the first time in 6 years that we have been able to do this and it will be like starting new again.”

“We recently tried to work out how to get rid of a few trees that we felt were a danger, but we were having trouble doing this due to the closeness of infrastructure. Now the problem is solved,” Dan added.

Unlike many industries, there are no counselling services to help rural farmers and their families through the emotional turmoil following a force majeure. As would be expected, Brian and Dan went through a kaleidoscope of emotions when they inspected the damage to their salad farm operation.

“That first 24 hours was a head spin, flat-out trying to clean up and make sense of it. I was enroute from Brisbane when the storm struck and it was dark when I arrived back at the farm. The next day I had time to look around and take stock; that’s when reality really set in. That was the hard day,” reflected Brian.

Despite the crop losses, customers, suppliers and employees stuck by the Clean Green team who were back in business and harvesting fresh lettuce and salad crops within three weeks of the storm.

“Times like this give us renewed appreciation for our friends, family, employees, customers and suppliers. They have all been great,” said Brian.

“Dan rang our employees the evening of the storm. The next morning they were all there early with a number of our friends with chainsaws and trailers to assist with the clean-up. We have a great team and are very appreciative of them. They worked their butts off that day in hot and extremely humid conditions.”

“This industry can wear you down after a few years and it sometimes takes something like this to motivate us into mentally regrouping ready for a new charge,” continued Brian. “We will learn from this, make a few changes and move forward,” he added.

Clean Green Hydro is insured by AON Risk Services (, a farm insurance specialist underwritten by CGU.

Farm vehicles were extensively damaged.

“They were excellent,” commented Brian. “I rang our Bundaberg-based broker on Friday and left a message. He called first thing Saturday and arranged for one of our vehicles to have a new windscreen fitted that day so at least we had a fridge van for Monday. He made sure he was contactable throughout the weekend, which made things much easier for us. The assessor arrived first thing Monday morning and was also very efficient.”

Growers can expect more extreme weather events

In addition to wild, violent storms, growers in Queensland and northern New South Wales have been inundated with heavy rains and floodwaters since late December 2007, with two-thirds of Queensland underwater and declared national disaster areas. How quickly the landscape has changed following a prolonged drought.

At its height, floodwaters covered two-thirds of Queensland.

The heavy rains were the result of intense monsoon troughs that swept across northern Australia during the 2007-08 monsoon season. If you talk to the locals they will tell you this year’s wet season is how it was before the drought. However, it would be foolhardy to think the seasons are normalising. At a recent climate change workshop organised by Growcom, an advocate organisation for the Queensland horticulture industry, grower delegates were warned to expect more intense storms and heavy rainfall for some time yet.

Flood waters can take several days to flow downstream.

According to south-east Queensland parsley growers Lisa and Ray Crooks from Riverview Herbs, the heavy rains need to happen to replenish the under-ground aquafiers and to fill many dry dams.

“This will create sustainability in the long run,” said Lisa.

“We were fortunate with the floods,” she continued. “The local river normally sits at half a metre, reached the 15 metre mark and luckily didn’t reach over the banks. Our issue was the back-up water from the river covering the entrance to the farm. This only lasts about two days when it happens.”

Floodwaters inundate this grower camp in the Beaudesert district.

Lisa and Ray own two farms in the Beaudesert district growing parsley in the ground and in raised hydroponic media beds. As long-time growers, they have experienced the emotional rollercoaster ride that comes with drought, storms and flood and they have developed some fundamental risk management strategies to minimise potential damage.

“When flooding is predicted, a lot of the harvested (plant) stock is bought back to this farm and stored in the cold room,” explains Lisa. “Ray has been a great weather man for many years; I knew he was expecting a great wet this year because I got my first clothes dryer for Christmas.

“When he prepares the land for summer, he always hills up the media rows as high as he can go,” she added.

Lisa advises that the internet is a great farming tool. For Australian growers, she recommends the Bureau of Meteorology ( The Bureau’s weather services encompass a wide range of forecasts, warnings, current weather observations and information services to the general public, national and international shipping and aviation, the Department of Defence and other groups. A number of offices around the country issue forecast warnings and other weather information and maintain a 24-hour, seven days a week weather watch service.

“From this website, we watch the weather, and forecasts, the rainfall data, and the river heights. We can have no rain here, yet up on the range further down the Logan River they may have a downpour which we can expect to see in two days time with rising river levels.

“As growers you try to implement risk management strategies as much as possible but no matter how hard you work, the likelihood of being affected by floods, mini cyclones, hail, etc., is a reality at some time during your farming life. It is how you deal with the situation that matters most,” she said.

Risk management strategies
So what can growers learn from these events to prevent or minimise farm damage during bad weather and extreme weather events?

Weather monitoring
By monitoring the weather growers can prepare for bad weather by ‘battening down the hatches’. For floodwaters and violent storms, this means sandbagging flood prone infrastructure and securing all loose items so that they don’t become flying missiles or floating obstacles. During Cyclone Tracy that devastated Darwin on Christmas eve 1974, the coastal buildings suffered little damage compared to inland structures that were flattened by a wave of flying debris that multiplied the further the cyclone travelled inland.

The weather bureau is also the first place growers should go before building new infrastructure to support hydroponic and greenhouse operations. The bureau offers detailed historical weather statistics for regions throughout Australia. However, violent storms and floods can and do occur anywhere and anytime in Australia, from the alpine regions of Tasmania to the tropical rainforests of northern Australia, and everywhere in between. Extreme weather events can also be unpredictable and arrive unexpectedly.

Building guidelines
Valuable information on building codes and local regulations can be obtained from your Shire Council. Greenhouse and system installation suppliers are also happy to supply technical information to back up the strength and integrity of their designs. More building guidelines can be found in the publications, Building a Greenhouse and Guidelines for the development of controlled environment horticulture, available from the NSW Department of Primary Industries ( Collectively, this information should give growers a clear understanding of what sort of infrastructure is required to withstand an extreme weather event in your region. Be sure to check the 100-year flood level.

Risk management strategies can also include the establishment of windbreaks, which should be located a suitable distance away from farm infrastructure to prevent crop shadowing as well as crop and building damage from falling trees. Check with your district horticulturist for the most suitable tree species to plant for windbreaks in your area.

Tree and shrub windbreaks are also valuable conservation tools with many functions. Their benefits include:
• Crop protection – Windbreaks can increase crop yields up to 44% ( Wind protection reduces crop water use, increases a plant’s ability to make food, and may increase pollination. The quality of fruit and other high value crops can be increased due to reduced sand and soil abrasion.
• Reduced soil erosion – Windbreaks prevent wind erosion for 10 to 20 times their height downwind. They also filter wind-blown soil particles from the air.
• Energy conservation – Windbreaks can reduce winter heating costs 20 to 40% by reducing cold air infiltration into buildings. In summer, water evaporation from leaves directly cools the air.

There are also other benefits in windbreaks including a home for wildlife, visual beauty, and tree products such as firewood.

Hail netting
For open-air hydroponic growers, the case for hail netting is strong and it should be considered in any risk management assessment.

“Most netting structures we manufacture and install are able to withstand wind loads up to 147kph and greater,” said Warwick Fletcher from Ballina-based Coast Guard Netting Services.

“The higher the shade factor, the closer together the cross cable span, the higher the wind rating,” he added.

By example, Warwick points to a netting structure on a production nursery in far-north Queensland that withstood wind speeds of 240kph (150mph) when Cyclone Larry struck during the 2005-06 Southern Hemisphere tropical cyclone season. The covering had a shade factor of 40% with cross cables every 6 metres.

“Only the side walls were blown out by the cyclone,” commented Warwick.

What makes these covers work so well is the structural system. The netting uses steel cross cables over the netting, which are high tensioned to give the structure rigidity and a long life span. They call this innovative system a ‘cable span’ structure. The pole supports are buried 1 metre in the ground and the cable rods (ends) are anchored to treated logs that are buried 2 metres underground. The cross cables are tensioned to 2 tonne and have a 5.2 tonne breaking strain.

“Once the cross cables are tensioned there is no movement,” explains Warwick. “The cross cables and anchors are designed to put the poles under compression,” he added.

Warwick commented that a properly designed and installed hail net structure with side walls would have withstood the driving winds experienced by the Childers growers and prevented or minimised crop damage.

The benefits of hail netting are primarily weather-related. However, from a grower perspective, the downside is loss of colour in leafy crops and, of course, the installation cost.

Back-up systems
Back-up systems such as an emergency generator to restore power are another risk management strategy. However, power generators come at a cost that may be prohibitive for small operators.

Standby generators are either engine driven or tractor driven. Either type can be stationary or portable. Engine driven units can be either manual or automatic start. Petrol, LP gas (bottled gas) and diesel-fuel engines are available.

Generators must provide the same type of power at the same voltage and frequency as that supplied by power lines. An air-cooled engine is often used for generators up to 15 kilowatts. A liquid-cooled engine is necessary for generators larger than 15 kilowatts. Engine capacity of 2 to 21/4 hp with the proper drive system must be available for each 1,000 watts of generator output.

Automatic engine-powered, full-load systems will begin to furnish power immediately, or up to 30 seconds after power is off. Smaller and less expensive part-load systems may be enough to handle essential equipment during an emergency.

Farm insurance
Not all insurers will provide cover for tempest or flood damage, sometimes referred to as ‘Special Perils’. A ‘tempest’ is defined as a violent windstorm, frequently accompanied by rain, snow, or hail, and a ‘flood’ is defined as water from a river, creek, lake, reservoir, dam or navigable canal that overflows onto normally dry land. You can be insured for flood damage caused by a broken pipe, but not for floodwaters spilling from a waterway. Damage from a tempest or floodwaters are seldom part of basic property insurance policies, and generally have to be added separately.

Make sure infrastructure such as farm vehicles are insured. Not all insurers include farm vehicles as part of their policy.

Few insurers cover clean-up costs, unless felled trees or other storm debris lie across infrastructure that needs to be repaired or replaced. Crop loss is another area difficult to get cover. One insurer that does cover clean-up cost and crop loss is Agricola Crop Insurance, the largest insurer of agriculture crops in Australia and New Zealand. Agricola specialise in protection against damage to greenhouses and crops (on an agreed value) in the one policy. Outdoor plant and propagation nurseries may be covered as well as other buildings directly associated with the business, such as packing sheds and cool rooms.

“The policy has been designed to meet the particular needs of today’s greenhouse and nursery producers,” said Agricola’s Rebecca Walkerden, “but the greenhouse policy does not cover open-air hydroponic crop production, nor does it cover trucks and vans – only assets directly associated with a greenhouse.”

Events insured against by Agricola include storm (including hail), water damage, fire, smoke damage, lightning, explosion, malicious damage, impact and earthquake. The Agricola policy includes a standard $15,000 clean-up cost, which can be increased for a higher premium. The policy also covers business interruption, machinery breakdown, electronic equipment, burglary and money lost or stolen during transit. The Agriocola policy can be viewed or downloaded from the insurer’s website (

Generally, the insurance industry has been slow to respond to insurance claims following a spate of extreme weather events up and down the east coast of Australia over recent months, and you can bet insurance premiums will soon rise.

Agricola Crop Insurance

AON Risk Services

Building a Greenhouse

Bureau of Meterology

Guidelines for the development of controlled environment horticulture

Utah State University Extension: Windbreaks Benefits and Design

Issue 83: Aquaponics Simplified

July/August – 2005
Author: Wilson Lennard

WILSON LENNARD outlines his research to develop a successful recirculating aquaponic system to produce Murray Cod and lettuce, with significant savings in water use and zero environmental impacts.

I came to the world of aquaponics from the other side , that is, the aquaculture side. Freshwater aquaculture is moving into a new phase and a lot of people are now turning towards using large, environmentally controlled indoor recirculation systems to grow fish. These systems are a self-contained unit, usually located in an insulated shed. These are high intensity systems, with tons of fish being produced annually on very small land areas. The advantage of recirculating fish farming is that water is recycled through the system, and is therefore used to its full advantage.

The downfall of any aquaculture operation is that fish produce waste, and this waste needs to be disposed of in a way that won’t impact on the environment. Fish waste is nutrient rich and if it is disposed directly to the environment, it can have negative consequences. This is where aquaponics and I come into it.

I was looking for a way to filter the nutrient-rich fish waste out of aquaculture systems. Solid fish waste is constantly removed from these systems and is usually composted, so it is not much of a problem. It is the water-bound fish waste that is a problem.

Around 70% of fish waste is actually water-bound, arising from the gas exchange of ammonia-type waste that the fish excrete across their gills. It is this water-bound component that I was looking to treat. So, from my point of view, I was looking for a way to remove water-bound waste from our fish culturing systems. This is required because fish farmers at present change approximately 10% of their water every day, to counteract this build-up of waste. Ten percent may not sound like much, but in a system containing 100,000 litres of water (which is not a large system), that means removing 10,000L of water a day, finding a way to dispose of it, and replacing it with 10,000L of clean, fresh water. So, as I said, I was coming at the problem from a fish culturalist perspective.

The great thing about this water-bound fish waste is that it is mainly nitrates and phosphates. As all hydroponic plant growers know, these are some of the main nutrients used for hydroponic plant culture. So the question arose, can these fish wastes be used as plant nutrients? This is where I started after obtaining a PhD scholarship through the Rural Industry Research and Development Corporation (RIRDC).

I set about designing and building an aquaponic system to integrate fish culture with hydroponic plant culture. I had to design a very small-scale system, as I needed to be able to replicate my experimental situations for scientific purposes. So I eventually ended up with 12 aquaponic units that were identical to each other.

A unit consists of a 100L fish tank with an associated biofilter. The biofilter is very important to the fish’s health, as it converts harmful ammonia released by the fish into harmless nitrate. Above the fish tank is a shelf containing a hydroponic gravel bed. Water can be pumped from the fish tank, up to the hydroponic gravel bed, and then returns to the fish tank. That’s it. It’s pretty basic, but it really works.

The theory behind aquaponics is this:the fish live in a tank, eat fish food, and produce two types of waste; solid waste (fish poo) and water-bound waste. As I said earlier, solid waste is routinely removed and generally composted. The water-bound fish waste is actually the same nitrate and phosphate hydroponic farmers add to their systems using inorganic salts that they purchase.

What was fish waste, is now plant nutrient. The water from the fish tank is pumped to a hydroponic plant culturing component and the nitrate and phosphate from the fish is used to feed the plants. The water, now ‘cleaned’ of nutrients, is then returned to the fish tank and the whole cycle begins again.

If the amount of waste the fish produce can be balanced with the amount of nutrient the plants require, then we should have a system where we can perpetually grow fish and plants in the same water, with no water replacement required, other than that used to replace transpiration from the plants.

So I set about running a number of experiments to develop the idea within an Australian context. Some of the questions that arose were:

– does this aquaponics thing really work?
– can Australian fish species be used?
– what pumping rates are required?
– what hydroponic systems can be used (gravel bed, floating raft, NFT etc.)?
– are there any nutrient deficiencies in the plants?
– is the system productive in a commercial sense?

The question of does the aquaponic process actually work was answered with my first experiment. One kilogram of fish was placed in the tanks and 20 lettuce seedlings planted. The fish were fed, the system monitored and the fingers crossed. It is an amazing thing to inspect an aquaponic system daily and watch both the fish and plants grow and thrive. After three weeks in the aquaponic system, I had harvest size lettuce (around 120g, Green Oak fancy heads), fish that had grown, and water with 80% less nutrient in it than the fish-only controls.

This was definitely a good way to start for a PhD student -success! The fish were healthy and had grown at a rate the same as the industry standard, with no side effects. In fact, they actually seemed to like their new, cleaner environment. The lettuce plants were full of head and a beautiful, rich green, with no signs of nutrient deficiency.

At this point I was wondering, is there really three years of research in this? What followed was two and a half years of further experiments and trials to try and optimise the system for better plant growth and better nutrient stripping from the system.

Well, we now have a system that is fully optimised and is ready for commercial trials. Some of the variables that you may be interested in include:gravel beds work better on a constant flow water delivery regime.

Past hydroponic research has suggested that a ‘reciprocal flow’ (water is pumped to the gravel bed now and then, instead of a constant flow) was better as it aided water oxygen levels and distributed nutrient to plants better. This may be true in standard hydroponics, but we always require oxygen above 5mg/L for our fish, so oxygen is always above what the plant roots require (around 2mg/L for lettuce).

Our constant flow gravel bed system grows lettuce about 20% better than a reciprocal flow. Gravel beds and floating rafts are about 15-20% more efficient than NFT. My experiments have proven, within an aquaponic context, that NFT is less efficient at plant growth and nutrient stripping.

The last key finding is that we need to use a potassium and calcium-based buffer system. Fish farmers use sodium bicarbonate and similar basic salts to make sure the pH doesn’t drop. Fish systems are the opposite to hydroponic systems – as fish eat and metabolise feed, the water pH drops.

To counteract this pH drop, we use buffers to keep the pH up around 7. If we use potassium and calcium-based buffers, we can add the potassium and calcium to the system that the plants require for good growth.

So I had better tell you of the key findings. Fish (we used Murray Cod) and plants (we used lettuce) can be grown in an integrated aquaponic system. If the correct balance is met between plants and fish, no nutrient build-up occurs in the system, and the plants get all the nutrients they need.

We don’t get conductivity build-up or drop-off;it stays constantly at about 500mS/cm. This is because the fish renew the nutrients every time they are fed, which can be as high as 3-4 times per day, and the plants constantly use those nutrients.

A combination of potassium and calcium is used to buffer pH and provide the other essential plant nutrients. We also add a little chelated iron, as fish food is lacking in iron and the plants require it to produce chlorophyll. That is all we add to the system – fish food, a little buffer each day, and a little iron once a week. All the micronutrients required for the plants are in the fish food, so we don’t need to add any of these.

There are several advantages; some relate to the fish and some the plants. Because we can balance the nutrient output of the fish with the nutrient uptake of the plants, we never need to exchange water. We do need to replace any water lost through plant transpiration, but this is a small amount. We are now saving above 90% of the water a normal recirculating fish farm would use. So, the system is very water friendly. We have no nutrient-rich waste output, we use our nutrients to feed the plants, and we have zero environmental impact.

Our fish grow just as well as they do in any other fish system. The best outcome is that we grow healthy, strong plants that yield at the same rate as they would in standard hydroponics. That’s right, our lettuce grew just as well in our aquaponic system as they did in our hydroponic controls. So, the advantages are:

– excellent fish and plant growth
– zero environmental impact
– efficient water use
– yields as good as the prospective stand-alone industries, and
– the ability to grow two cash crops (fish and plants) off the one food source.

I am now building a commercial-scale aquaponic system. We will have the ability to grow around 500kg of fish a year and harvest 3,000 lettuce per week. We will have no environmental impact and will use less than 10% of the water a normal recirculating fish farm would use. The only other question is whether we can obtain ‘Organic’ certification? If we can achieve this, we believe we are on a definite winner. But more about that in a coming issue.

About the Author
Wilson Lennard is in the final stages of his research into aquaponics at RMIT University, Melbourne, Australia. He believes aquaponics is a new and emerging industry that will fill a defined niche in the aquaculture/hydroponics market.

Issue 82: IPM Practices for Outdoor Growers

May/June -2005
Author: Michael O’Dea

Following a cancer scare, MICHAEL O’DEA moved to south-east Queensland where he established an eco-friendly, outdoor hydroponic facility, adopting IPM practices and biocontrols to grow pesticide-free lettuce, herbs and Asian greens for the health food market. His story first appeared in the November/December 2004 issue of Practical Hydroponics & Greenhouses. Here, the grower gives us an update.

Well, 10 months later;how did we go? What were our goals and did we achieve most of them? To answer the first question, it is necessary to review our objectives, which are best summarised in an article authored by Dr Porter and published in Practical Hydroponics & Greenhouses (Impact of Global Market Drivers, Sept/Oct 2004). This article highlighted a number of issues that will influence future food production practices worldwide.

In his article, Dr Porter said that in the future, food will be produced using very different technologies than are used today. “Public concern over food safety (particularly chemical residues) and environmental flow of pesticides and nitrates into the environment are having a huge impact on crop production systems,” he said.

Dr Porter pointed to water conservation and water use efficiency as other major problems facing the world and, of course, is a major issue here in Australia. He also points to energy audits on production and anti-GMO sentiment as market drivers that will force growers to conform to stringent quality assurance guidelines to meet food and environmental safety standards;standards that are already embraced by many northern European countries. “In the next decade, ‘clean and green’ will mean zero pesticide residues in food and will require proof that crop production practices do no harm to the ecosystem, otherwise growers will face the prospect of environmental tariffs,” Dr Porter said.

We figured that people have to eat and they will want nutritious, pesticide-free food. We attended a nearby Saturday morning grower market on the Gold Coast for three weeks and we sold out of our product very quickly. The consumer reaction to the pesticide-free, no soil organisms, no herbicide concept was really positive, and it gave me a chance to explain to customers that we were not organic, but a viable alternative.

Unfortunately, the other growers didn’t see it that way and complained we had taken a lot of business away from them (which was true). The market organisers decided to listen to these growers;not the customers. We were not invited back.

Marketing-wise, a lot of what we did was guesswork. We knew we could grow a good product because we had undertaken formal training at Burnley College, Victoria, and had 20 years experience as commercial growers. What we did not have was knowledge of the varieties the market wanted, which meant we wasted time growing the wrong varieties. It also took some time to grow the right crop to suit the climate. We are still learning. As Rick Donnan has said many times in his column, Reader Inquiries, hydroponic technology represents only 10% of skills required to grow a marketable crop;the other 90% is based on knowing your crop and having the growing skills.

We now deal with a wholesaler at Rocklea Market, Brisbane, and a supermarket chain. We also supply restaurants direct. In a way, that suits me fine as we no longer spend all day at a market, which can be time-consuming.

The majority of hydroponic growers know how efficient hydroponic systems are in terms of water and fertiliser use. In our case, we use 700 litres of water to produce $100 worth of produce as opposed to the scandalous 750, 000 litres of water to produce $100 worth of rice. As well as the usual fertilisers, we add in our own organic ‘herbs and spices’ to get optimum crop health, and we do not dump water every so often.

We use town water which is chlorinated. Our water quality is atrocious and hovers around EC 0. 8-1. 2 – the water contains a lot of dissolved solids. In spite of the handicaps, we still produce an excellent product.

Our water and fertiliser costs are small. There is also no run-off into the environment – we recycle the water. If we need to bleed solution, we irrigate fruit trees and potted herbs.

Hydroponic and greenhouse growers have many advantages over traditional soil growers. I can’t see why hydroponic growers need GMOs, because we do not need to weed, and we can spray on friendly Bacillus thuringiensis (Bt) to aid in controlling a number of harmful insects, if we need to. We do not need to use ozone depleting methyl bromide – our production level per sqm is far higher than can be achieved by growing in the ground. We use very little in the way of pesticides, and hydroponic growers are allowed organic inputs, such as Eco Oil and soap sprays to counter insect pests and diseases. We grow our crop in polyethylene channels;we do not use PVC.

In Europe, especially in Scandinavia, many crops are grown hydroponically without the use of pesticides using biocontrols to keep pest problems in check. Water and nutrients are also recycled.

Our objective at the Squeaky Green farm is to avoid the use of toxic chemicals on the vegetables we grow to give consumers a pesticide-free product. To achieve this, we use biocontrols to keep most of our pests under control. We release hypoaspis predatory mites every fortnight to keep fungus gnats and thrips under control. We were given some rove beetles ages ago by Biological Services in Loxton, SA, to control fungus gnat, thrips and shore flies, and we still see these beetles in the media when we are working around our crop. We keep a constant look out for pests in the crop and eveyone who works at Squeaky Green monitors the crop for pests and beneficials during their work routines. A daily record is kept of the status of the crop, where beneficials are released, and where pests are found.

Because we use friendly bugs, they put a constraint on what we can use in the way of sprays. If we have to use sprays, then they have to be biorationales. We did start off by using pyrethrums, which are an allowed organic input, but we found it tends to knock off beneficials as well as insect pests.

We have found we get a very good influx of aphidius parasitic wasps to control aphids (Myzus persicae). We also get a variety of ladybird (Hippodamia convergens) that feed on aphids. We are exploring the possibilities of growing banker plants to keep a population of parasitic wasps on hand.

We have found ants are our biggest problem – the ants farm the aphids for their honeydew secretions. We use boric acid and sugar as a bait, and greasing around the legs of the tables tends to keep the numbers down.

As far as the aphids are concerned, if we keep a careful eye on our Asian veggies, we know where the aphids are and we can get rid of them by spraying them with Eco Oil. I only use a small pack to spot spray hot spots. We did get some large brown aphids (Uroleucon sonchi) on our lettuce in the winter months, but they seemed to disappear by spring.

We also release green lacewings fortnightly and they do a great job of cleaning up anything they can get their fangs into; including my arm.

Micheal and Jant O’Dea inspect the crop for pest.

I have seen a few whitefly on our sticky traps, but numbers have never increased, so maybe the lacewings are eating any nymphs. We have a resident population of brown frogs in our flood and drain trays.

I think our worst problem is going to be Rutherglen bugs (Nysus vinitor) in late spring/early summer. We struggled with them in 2004. Many conventional growers have the same problem. Complete exclusion is possible but it restricts the air flow around the crop too much. Has anyone got any help on this topic? I have talked to a number of entomologists in the IPM area and they all tell me Nysus vinitor is very hard to control biologically, as are mirrids, another sucking insect. I do have some strategies in mind, such as growing a trap crop which I can use to attract the bugs away from our veggies.

The Vortex Bug Bin light trap is most effective inside the netting

Lepidopterous caterpillar pests are not a problem for us as we use netting, and we also use a Vortex Bug Bin light trap. We started off by putting the light trap inside the netting, but we have since moved the trap just outside the netting. This device has proved invaluable to us because it traps so many bugs. I do not know all the bugs it traps but I did have a talk to Dr Richard Drew at Griffith University, Qld, who has worked with the light trap. He is enthusiastic about its ability to trap bugs of the crop-eating kind.

This innovative product has enormous potential in many areas of crop production including vegetables, turf, macadamias, lychees, cotton, and anywhere where the Coleoptera beetle and Lepidoptera caterpillar are a problem for growers. Redlands nursery just outside Brisbane has used the Vortex light trap for four years and they say they could not do without it now.

According to evaluation tests carried out by CSIRO Entomology at the Australian Cotton Research Institute, Narrabri, NSW, the overall results of the Vortex light trap were positive. The data shows that Helicoverpa caterpillar densities were substantially reduced within and around the array of Vortex light traps. It must be stressed that this work only involved two fields over part of a single season. Such unreplicated experiments require cautious interpretation because other (unknown) factors could contribute to the differences shown. The CSIRO study showed promising results, but it also highlights the need for careful evaluation in the future.

The Squeaky Green farm specalises in pesticide-free Asian herbs and lettuce.

‘Clean and green’ will mean zero pesticides in fresh produce with no harm to the environment, and some kind of proof to show that these standards are achieved. Labels on food to indicate that it is produced in a sustainable way is one way to demonstrate proof. For example, in Belgium, over 2,000 growers market under the Flandria label, where the motto is ‘Quality Vegetables – Approved by Nature’. In Australia, Freshcare does address grower accreditation to some extent.

So far, we are not really emphasising the fact that the Squeaky Green farm is pesticide free. I need more time to find out how far into the season we can go with no pesticides. We have had to use azoxistrobin to treat small amounts of septoria and pythium.

We use a bio-friendly trichoderma fungi in the water to suppress disease organisms and it appears to work really well. I have a microscope and I can diagnose the most common fungal pathogens by the shape of the spores. On the subject of diagnosis, I use a 12x magnification lens, which I bought off my optician, to identify insect pests and diseases.

We had a touch of albugo (also known as white rust) on the Asian greens. It only appeared on one plant variety and we have stopped growing this crop until the weather conditions are no longer conducive to the disease.

Our quality has been excellent all the way through the season and we have gained sales by having a better quality product than the ground growers. By the end of the year, in time for summer, we will have 5,000 sq. metres of production area.

What we do need is like-minded growers to try and achieve ecologically sustainable standards and to put together a label that consumers will recognise.

For soil growers, there are some encouraging technologies being used to conserve water and nutrients. Dr Richard Stirzaker from the CSIRO has invented a soil probe which enables ground growers to monitor nutrient usage where water is in the soil profile. The device is called FULL STOP and can be used to give precise water and nutrient doses. Mulch techniques have also been developed to avoid disturbing soil profiles. By growing a cover crop, the resulting problems of bare earth can be avoided.

It is up to us as growers to start to implement sustainable growing systems, and here at Squeaky Green, we have a lot of answers to the problems we have experienced so far. It would be good to get some kind of Internet chat room going for likeminded growers.

I would like to thank my wife Janet and daughter Nicola for helping to achieve our goals. Without their eagle eyes, we would not be able to be Squeaky Green.

For further information contact Michael O’Dea at email:

Issue 78: Lettuce – From Wild Weed to Functional Food

September/October – 2004
by: Rob Santich MNHAA

Since its development from wild species, the lettuce in all its ingredient. It is thought that the first cultivated crop varieties has become the world’s most popular salad originated in or around the Mediterranean basin. The supporting evidence for this is the existence of a transitional, nearly wild species of lettuce. The morphology of this nearly wild species indicates that it originates from Lactuca serriola, commonly called pricking lettuce, in reference to the bristly stems and leaf margins. Cooking oil is extracted from the seeds of Lactuca serriola to this day, as it was in ancient Egypt. The second piece of compelling evidence is found in the tombs of the ancient Egyptians.

Archaeologists have discovered tomb paintings of bundles of prickly lettuce and these have been dated to be 4,500 years old1.

The first written records of lettuce cultivation and consumption was by the first ancient Greek historian, Herodotus. He recorded that lettuce appeared on the tables of the royal family of Persia in 550 BC. Lettuce was later described by various individuals:the ancient Greek physician and teacher of medicine, Hippocrates, in 430 BC described the sedative properties of the sap derived from the wild species as well as the health benefits of the cultivated variety; Aristotle, the ancient Greek teacher and philosopher, in 356 BC; and Galen, one of the most famous ancient Greek physicians and physiologists in 164 AD described lettuce as a popular salad vegetable1.

It appears as if lettuce was also popular in ancient Rome and several species had been developed and cultivated. Columella, a Roman writer on agriculture, described four species in 42 AD; and Pliny, the Roman author described nine varieties in 79 AD 1. The Roman Emperor Augustus attributed his recovery from serious illness to his treatment with wild lettuce. He was so impressed and thankful, he had erected an altar and a statue in honour of the plant 2.

In terms of the culinary variety, it was probably through the expansion of the Roman Empire that lettuce cultivation and consumption spread through northern and western Europe 1.

The cultivation of the Romaine or Cos lettuce spread through out the Mediterranean region, where to this day it remains the principle lettuce variety cultivated in southern Europe, the eastern Mediterranean coast and north Africa. The term Cos lettuce is highly suggestive of an early usage on the Greek Island of Kos. Leaf types and Latin lettuce were probably developed from the Romaine lettuce, as its morphology is similar but with shorter leaves and a softer texture. Butterhead is similar to Latin lettuce so it is likely that it was developed from it. The soft-headed crisp types, known as Batavia lettuces, were probably developed sometime later from leaf types that formed rudimentary heads under cool conditions 1.

Lettuce, along with other vegetables and fruits, was taken to the New World by the Italian explorer, Christopher Columbus. Peter Martyr d’Anghiera, a Spanish chronicler and historian who recorded the exploits of many Spanish explorers as well as Columbus, recorded the presence of lettuce on Isabella Island in the Caribbean in 1494, suggesting it arrived on Columbus’s second voyage of discovery 1.

During the early years of the Unites States, an assortment of cultivars and leaf types were grown, initially in home and farm gardens and later in market gardens around cities. During the early part of the 20th century, great developments in the shipping and transport industries allowed the expansion of new markets with increasing popularity.

It is likely that lettuce arrived in Australia with the first fleet, along with the unintentional delivery of many exotic weed seeds.

Two species of prickly lettuce grow wild in Australia, Lactuca serriola and L. saligna or willow leaf lettuce. Their distribution is wide, although L. saligna is not found in the Northern Territory. The plants are found as garden weeds, on roadsides and wasteland, as well as degraded pastures 3.

The Lactuca spp. are members of the family Compositae, sub-family Ligulifolae, and the order Campanulaceae. The Ligulifolia subfamily is characterized by the presence of latex vessels with the presence of essential oils a rarity. Other members include the common weeds with medicinal properties, Taraxacum officinale (Dandelion) and Cichorium intybus (Chicory) 4.

As lettuce growers and observant lettuce consumers are aware, all lettuce varieties exude a milky latex to varying degrees, mainly from the stem and leaf nodes when traumatised. The latex is particularly noticeable in stem varieties. It’s this latex that imparts a bitter taste to lettuce leaves, and of course is considered undesirable in commercial lettuce. However, this bitter latex has significant medicinal value. Throughout history, medical writers and physicians have recorded the health benefits of consuming lettuce as well as the medicinal properties of the milky latex. For example, Dioscorides, the ancient Greek military surgeon and naturalist, in his work De Materia medica, makes reference to the sedative properties of garden lettuce as well as the properties of the latex of the prickly lettuce, where he compares the sedative effect of the prickly lettuce to that of the opium poppy5.

In 1792, Dr Koxe, a medical doctor in Philadelphia, began to collect the milky latex from Lactuca sativa, dried it and prescribed the exudate as a substitute for opium. The news of this medicinal use soon spread through the medicinal community in the US and also to Europe. In Europe, the plant source of the latex was Lactuca virosa, but at that time in the US, Lactuca virosa had not introduced itself onto the landscape (Lactuca elongata, which grows wild in the US, seems to have been overlooked at this stage). As Lactuca virosa is a more abundant source of latex, Europe became the major producer of Lactucarium5.

Medicinal research on animals began in 1819 with Dr Ganzel of Berlin performing studies on dogs, noting that Lactucarium produced a profound sleep 5. Later in medical history, Lactucarium became an official drug of medicine and earned monographs in the Eclectic texts King’s American Dispensatory (1898), and The Eclectic Materia Medica, Pharmacology and Therapeutics by Harvey Wickes Felter MD (1922), as well as The British Pharmaceutical Codex (1911). These texts are still referred to in modern phytotherapy, as they represent credible traditional evidence for the use of herbs and are available on the internet in their entirety ([url]www.[/url])

Research into the identification of the phytochemicals present in lettuce latex began quite early in plant research history and this early research is thoroughly dealt with in reference ‘5’. More recently, with the development of sophisticated analytical equipment and methodologies, the phytochemistry of lettuce latex has been fully elucidated. The major constituents appear to be the sesquiterpene lactones, lactucin, deoxylactucin and lactucopicrin 6. Sesquiterpene lactones are pharmacologically active phytochemicals that also impart a bitter taste onto those plants they accumulate in. There are over 3,000 sesquiterpene lactones known and a good portion of them occur in the family Compositae and are considered a phytochemical characteristic of the family7. Other sesquiterpene lactones of interest are: artemisinin from Artemisia annua (Qing hao), which has antimalarial properties;and parthenolide from Tanacetum parthenium (Feverfew) with anti-inflammatory properties7.

Researchers have classified the sesquiterpene lactone group as phytoalexins, which form a part of the chemical defence network developed by plants and protect the plant from pathogenic attack 6,8. Sesquiterpene lactones are also known for producing contact allergic reactions7.

The sedative effect of wild lettuce has been attributed to the sesquiterpene lactones, lactucin and lactucopicrin 9, and in modern Phytotherapy is utilized principally in galenical extracts rather than extracts of the latex, and is prescribed to treat sleep disorders, restlessness, nervous excitability particularly in children, and irritable cough9.

The K vitamins, a group of napthoquinones, are required for the carboxylation of number of proteins, including the bone matrix protein osteocalcin10helping to strengthen the bone matrix. There is emerging evidence that suggests that vitamin K may have protective effects in terms of age related bone loss, and epidemiological evidence is suggestive of an association between low vitamin K intake and an increased risk of osteoporotic fracture risk 11.

Vitamin K occurs as a series of compounds with a common napthoquinone nucleus and differing isoprenoid side chains. The form that occurs in plants, phylloquinone or vitamin K1, is the major dietary source and is found in green leafy vegetables and certain vegetable oils, such as soybean, rapeseed and olive oils12. Vitamin K1 is associated with and most abundant in, photosynthetic tissues of plants;therefore, the greener the leaf, the higher the vitamin K1 levels13.

The most well-documented role of vitamin K is in the liver, where it acts as a cofactor in the coagulation cascade resulting in blood clotting. In fact, the “K” is derived from the German word “koagulation”14. Some people are at risk of forming blood clots, which can block the flow of blood in the arteries of the heart, brain or lungs resulting in heart attack, stroke or pulmonary embolism. These people may be prescribed anticoagulants such as warfarin, which inhibits coagulation through the antagonism of the action of vitamin K. Consequently, patients taking these drugs are cautioned against consuming large quantities of vitamin K containing foods in their diet15.

Vitamin K2, or menaquinone, is synthesized in the human gastrointestinal system by microflora and appear to be a minor portion of the daily requirement for vitamin K 12, 15. It appears as if approximately 60 to 70% of the intake of the vitamin K group is lost to the body through excretion, which emphasizes the requirement for a continuous dietary supply to maintain tissue reserves 12,1.

In Australia, there is uncertainty with regard to setting an RDA because of the variable production of vitamin K by bacteria in the colon. The requirement is believed to be 1µg/kg body weight/day16. Nutritional texts in references to data from the USA, commonly state that the average American diet contains between 300 and 500mg of vitamin K per day, which far exceeds the 1µg/kg body weight/day requirement16. Presuming the Australian diet is approximately similar to the US, one could assume that people in both countries are unlikely to suffer vitamin K deficiency. However, reliable data on the vitamin K content of foods has demonstrated the vitamin K intake of many individuals fails to meet the 1µg/kg body weight/day requirement16. The evidence suggests that even the requirement of 1µg/kg body weight/day may not be enough for vitamin K to maximally carboxylate the bone matrix protein osteoclacin16.

Osteoporosis is a skeletal disorder in which bone strength is compromised, which results in an increased risk of fracture. Sustaining a hip fracture is one of the most serious consequences of osteoporosis17. Worldwide, almost 50% of women and 30% of men will suffer a fracture related to osteoporosis in their lifetime, and in Australia the estimated direct cost of osteoporosis related fractures is $800 million annually18.

The term osteoporosis means bone fragility and is synonymous with low bone density. Undoubtedly, osteoporosis is a multifactorial disorder with nutritional factors such as vitamin K, vitamin D and calcium intake being several factors contributing to an increased risk of fracture. Other factors include, but are not limited to, increasing age, female gender, oestrogen deficiency, smoking, metabolic diseases, such as hyperthyroidism, and the use of corticosteroids and anticonvulsants17.

Positive studies have taken place investigating the hypothesis that high intakes of vitamin K are associated with a lower risk of hip fracture in women. A prospective analysis within the Nurses’ Health Study cohort involving 72,000 middle-aged and older women and taken over 10 years, concluded that low intakes of vitamin K is associated with an increased risk of hip fracture. Within this study the researchers took a closer examination of iceberg and romaine lettuce, spinach and broccoli, as these were the greatest dietary contributors to the vitamin K intake in this cohort. The researcher examined whether these foods had protective effects against hip fracture in a similar manner to that observed for vitamin K intake. Women who consumed lettuce one or more times a day had a 45% lower risk of hip fracture than women who consumed lettuce one or fewer times per week. There was no observed association with spinach or broccoli, although this may have been due to the lower frequency of consumption of these foods19.

The Framingham Offspring Study is a longitudinal, community based study of cardiovascular disease among the children and spouses of the participants in the original Framingham Heart Study cohort. Between 1996 and 2000, there were 3,532 participants in the sixth examination cycle of the study. The data examined from this cycle found higher vitamin K intakes were associated with higher bone mineral density (BMD) measurements20.

Numerous clinical studies have demonstrated that the supplementation of vitamin K alone or with other vitamins or minerals increases carboxylation of osteocalcin in post menopausal women with osteoporosis21, reduces serum undercarboxylated osteocalcin in elderly women with osteoporosis22, increases BMD in post-menopausal women with osteoporosis 23, and has a protective effect on prednisolone-induced loss of bone mineral density24.

Green leafy vegetables (GLV) offer an inexpensive source of antioxidant phytochemicals. In a study examining the antioxidant potential of 30 GLV, concluded that lettuce, omum and radish leaves demonstrated the highest values25.

It appears as if fresh lettuce is best in terms of antioxidant capacity when compared with lettuce stored under modified-atmosphere packaging (MAP) in studies performed on 11 healthy volunteers:the fresh lettuce demonstrated significantly greater antioxidant activity over lettuce stored under MAP26.

Lettuce has indeed moved from wild weed to functional food, and with adequate intake, seems to have some protective effect in terms of osteoporosis. As an enthusiastic neophyte home lettuce grower, I am encouraged by not only this research but what I’m producing from my own NFT unit. There is nothing like providing fresh lettuce leaves for the daily salad at family meal times. Now where did I leave my Lactucarium!

RobSantich MNHAA has over 20 years’ experience as a herbalist and medicine maker. Amember of the Complementary Medicines Evaluation Committee (CMEC) expert advisory panel, Rob is also Botanical Medicine faculty head at the Australian College of Natural Therapies and has served as an examiner on the board of the National Herbalists Association of Australia. He now runs a herbal practice in Newport, Sydney, and teaches classes in herbal manufacturing. Email:

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