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Wild Storm Shreds Lettuce
Author: Steven Carruthers
Practical Hydroponics & Greenhouses

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

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