Posts Tagged ‘ NFT ’

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.

Ozonation
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 (www.flairform.com.au).

“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
Email: gary@ghostgully.com

Joe Crane
Cyber-Hydroponics,
PO Box 3918, Burleigh Town, Qld 4220
Mob:0416 232 030
Fax: 07 3319-0926
Email: web@cybhyd.com
Website: www.cyberhydroponics.com

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
Email: info@blackmaxozone.com.au
Website: www.blackmaxozone.com.au

Graeme Wright
WiSA Irrigation Solutions,
PO Box 592, Echuca, Vic 3564
Ph: 03 5480-7713
Fax: 03 5482-3736
Email: sales@irrigatewisa.com.au
Website: www.iisystems.com.au

Issue 103: Sustainable Aquaponics

November/December – 2008
Author: Dr Brett R. Roe and Prof David J. Midmore

Is aquaponics technology a viable option for potential investors? In this critical assessment the authors highlight issues constraining the development of a sustainable commercial aquaponics industry. They also report on their investigation of linking vermiculture with aquaponics.

By Dr Brett R. Roe and Prof David J. Midmore

First vermiponic NFT trial growing Pak Choi (Brassica rapa, var chinensis).

There are valid arguments as to why aquaponics may be an ecologically-minded and economically viable option for potential investors. However, at this time, the vast majority of aquaponic systems are simply not sustainable. Furthermore, there are other issues that must be considered by anyone contemplating aquaponics, such as the current climate of the Australian industry, hurdles regarding organic certification, and the lack of data that could be used to accurately model aquaponic systems. We propose that the foremost issue regarding the future of the aquaponic industry is the necessity for the continued development of sustainable aquaculture (fish) feeds. Finally, we suggest for those contemplating aquaponics, that they first consider what consultation services, system design, management tools, operating methods and economic structure best suit their needs, skills and budgets.

The Integrated Waste Reclamation and Animal-Plant Production Systems project is undertaking an investigation of vermiponic and vaquaponic methods that aim to generate vermiculture liquor and castings, chemical-free hydroponic plant produce, and live earthworms from abattoir paunch and aquaculture waste via the use of food web conversions and physical linkages. Both vermiponics and vaquaponics represent theoretical and technical progress toward sustainable primary production, which if practised widely, could impart substantial decentralised effects upon waste management, chemical-free food production, soil development and other associated aspects of resource management, environmental stewardship, economics and community health.

Replicated vermiculture conversion pits.

Mr. William ‘Brock’ McDonald, CQ University Vermiponic/Vaquaponic Technician, quantification of earthworms.

Beef cattle paunch waste.

Close up of beef cattle paunch waste.

Ms. Elena Tchurilova, CQUniversity Hydroponic Researcher and M.Sc. degree candidate.

NFT Pak Choi (Brassica rapa, var chinensis).

Aquaponics

There are several arguments as to why aquaponics may be an ecologically minded and economically viable option for potential investors (especially for backyard, hobby or micro-commercial scale systems). These include, but are not limited to, increased efficiency of water usage and treatment, the potential for branding diversified products as organic (or chemical-free), and supply of niche markets. There are a host of aquaponic publications and other sources of information, in most instances generated by a relatively limited number of experts, that discuss the positive aspects of aquaponics in-depth and therefore this article will not further reiterate those viewpoints.

The reality is that the vast majority of aquaponic and aquaculture systems are, at this point in time, simply not sustainable. This is due to the fact that these systems utilise commercially available aquaculture feed (fish meal pellets – fish oil supplements), of which many are partially or mostly composed of fish harvested from wild habitats in volumes and at rates that outstrip the capacity for population recovery.

Of course, aquaponic practitioners cannot be faulted for using such feeds for obvious reasons: the product is affordable, widely available and is readily consumed by fish; the product is high quality in terms of composition and shelf life; there is consistency and ease of application; and most importantly (from the perspective of aquaponics), the composition of the resulting fish metabolic wastes require minimal (if any) fortification and/or enrichment of macro and micronutrients to grow a broad range of plant species.

We suggest that the foremost issue concerning the future of both the aquaponic and aquaculture industries is the necessity of the continued development of sustainable aquaculture (fish) feeds. Leaders of, and experts within, these industries must increase investment in the development of sustainable feeds in order to avoid further damage to natural fisheries and the hastening of the decline of aquaculture-based industries on a global scale.

Commendable efforts by a number of companies, research groups and individuals around the world are underway to further develop aquaculture feeds that are composed of renewable plant and insect ingredients or developed from organic waste sources and/or that are more assailable (e.g. less metabolic nutrient waste by-product). The latter of which may occur to the detriment of aquaponics as the technology, as practised in many configurations, is dependent upon fish metabolic by-products to support plant growth.

In addition to unsustainable aspects of aquaculture feeds, there are other issues that must be considered by anyone contemplating aquaponics as an enterprise, which include but are not limited to the points listed below:

Methodology: A widely accepted aquaponic method requires that aquaculture and hydroponic systems are to be hydrologically linked via in-line recirculation in real-time, and managed primarily for plant production because the plants represent the product from which the bulk of revenue can be generated (Lennard, 2007). The goal of the method is to closely match fish metabolic outputs (the only source of plant nutrients utilised other than carbon) to the plant nutrient requirements, resulting in a near-zero nutrient waste stream; a worthy goal indeed. Therefore, aquaculture enterprises opting to move into aquaponics following that method must prepare for a shift in market focus away from selling fish as the primary product to selling plant produce as the primary product.

Competition with the many dedicated commercial aquaculture and hydroponic producers aside, that method (as far as we are aware) has yet to be successful at any substantial commercial size (e.g. product sales ≥ $200,000 per year) over periods of time that lend stability to the business within the marketplace (e.g. ≥ 5 years). However, it is certainly possible (as some reports suggest) that aquaponic systems are achieving levels of commercial success following the widely accepted method. We urge owners of those systems to allow accurate and detailed documentation of the inner workings of those systems for the benefit of the industry as a whole.

Furthermore, hydroponic linkages to aquaculture businesses that do not aspire to the widely accepted method, but focus on aquaculture as the primary enterprise without focusing on near-zero nutrient waste streams, have been operating successfully at commercial capacities for some time.

Fish as Bio-converters: Rarely is the decision to integrate fish culture into commercial hydroponic systems based on the desire to expand product range. This is particularly true when considering the widely accepted aquaponic method described previously. The fact is that fish within aquaponic systems are primarily viewed as bio-converters used to process fish feed into soluble plant nutrients. The rationale supporting this view commonly centres on the desire to avoid using petrol-chemical derived inorganic hydroponic nutrients because of (1) the environmental impacts associated with their production, use and disposal, (2) the rising cost of inorganic hydroponic nutrient solutions, (3) the ‘chemical’ stereotype that may tarnish the perception of inorganic hydroponic produce, and (4) the inability to potentially market hydroponic produce as chemical-free or organic if grown using inorganic nutrient sources.

In response, we suggest that it is very difficult to accurately determine which source of hydroponic nutrients (i.e. petrol-chemical derived or bio-converted fish feed) causes more or less environmental damage when considering their production, use and disposal from a global ‘cradle to grave’ perspective. For hydroponic practitioners who produce excess nutrient waste streams, it may be possible to implement low-tech methods of managing those waste streams with the added benefits of enhancing local biodiversity and possibly generating a secondary agri-product (e.g. constructed wetlands).

With regard to rising costs of inorganic hydroponic nutrients, we again suggest it is difficult to accurately determine the long-term economic trends of the hydroponic nutrient industry as opposed to aquaculture feed industry. Additionally, when applied to hydroponic systems, the true costs of nutrient use become site-specific due to specific system designs, management and production methods, environmental aspects and other unique factors.

As for negative perceptions, we believe the hydroponic industry has, for the most part, successfully overcome this issue, and that most consumers are now accepting of inorganic hydroponic produce. Furthermore, the issue of organic or chemical-free hydroponic and/or aquaponic produce is not only a question of definition and methods of production, but more important is the state of competition with traditional agriculture and aquaculture industries and the influences those industries have upon collateral organisational and governmental policy and regulation.

Hence, given these and other arguments presented in this discussion (e.g. technical challenges of adding aquaculture to hydroponics), whether or not it makes sense to integrate fish as bio-converters into commercial hydroponics is a debatable issue. We suggest as an alternative that the hydroponic industry invest in the development of hydroponic nutrient solutions that are generated from renewable resources and/or organic waste sources.

Industry Experts: It may be difficult to obtain unbiased opinions and recommendations regarding the design and operation of aquaponic systems as profitable and stable businesses of commercial scale because conflicts of interest may exist with aquaponic experts (e.g. researchers, consultants, system designers and aquaculture/hydroponic distributors), who profit from selling aquaponics in one way or another. The majority of experts who sell aquaponics have not, do not, and possibly could not make an exclusive living by managing aquaponic systems or otherwise selling animal and plant products produced in aquaponic systems they themselves own or operate. To obtain overtly cautionary or negative consultation with respect to investing in an aquaponic system is unlikely, even if expert consultants have never achieved commercial success over periods of time that lend credibility to their skills and the aquaponic methods they endorse.

Counterbalancing that, those who champion aquaponics are necessary if the industry is to improve, evolve, gain credibility and proliferate. Therefore, until unequivocal, reproducible and transparent evidence (biological, economical, geographical, and methodological) proves validity beyond a doubt, we suggest that consultation grounded in commercial success and factual information (both positive and negative) must be the goal for any reputable aquaponic expert. Furthermore, performance bonds linked with consultancies and design services (which are standard practice in many industries) would most certainly give credibility to consultancies confident enough in their skills and aquaponic technology to bond their services and products. Consultancies would then take a fiscal responsibility for the outcomes of the systems they are involved with from a design, operational and production standpoint.

Industry Representation: In Australia, ongoing attempts to form organisations that aim to represent a unified aquaponics industry have achieved limited success. Loosely defined factions and individuals within the Australian aquaponics community have emerged and maintained degrees of separation between themselves. It is our view that this has occurred due to differing opinions and conflicting experiences regarding aquaponics and aquaponic methodology, and the ever-present lure of profit to be had by those who aspire to dominate the fledgling industry. Problems such as these are not confined to the aquaponics industry, as similar problems exist in most primary production industries.

Such a lack of cohesiveness among experts and practitioners imparts an embarrassing weakness to the Australian aquaponic industry that can only be rectified when all those involved exercise humility and work together towards the progression of the industry in a professional and altruistic manner. To begin with, we suggest that the most commonly referred to definitions of aquaponics (which underpin the widely accepted method of aquaponics described earlier) be broadened to include integrations that practise any method of aquaculture linkage to hydroponics. This shift in philosophy stands to embrace practitioners currently alienated by narrow definitions that only recognise methods of in-line recirculation (i.e. hydrologically real-time linkage between the aquaculture and hydroponic enterprises). Also, if standard aquaponic methods (SAM) come to form through suitable channels of industry consensus, we suggest they include as a primary tenet the use of sustainable feed sources in applications where it is technically and economically feasible.

Furthermore, any individuals that comprise a representative organisation must not aspire to make a profit from the aquaponic industry directly, indirectly, collaterally or otherwise. Individuals given the honour to represent the industry from apex positions of authority and influence must not accept substantial payment in any way, shape or form, but serve the industry for the good of the industry itself without prejudice or ulterior motive. This condition may be difficult for some to accept, but nevertheless it would most certainly alleviate many conflicts apparent at the national organisational level.

Of course, there are other tenets by which any representative organisation must abide; the subject of which could embody a protracted discussion paper.

Certification: Government agencies and certification organisations have yet to legislatively embrace aquaponics in a way that would allow the industry to capitalise on aspects of aquaponics (e.g. chemical-free or organic branding/certification) that could make those businesses more competitive with stand-alone aquaculture and agriculture operations. Hence, a unified aquaponic association that took on the role of organic certification of aquaponic products could fill a position where a void currently exists. Whether or not any future certification body would fall victim to the organisational pitfalls discussed earlier is unknown, but we remain optimistic.

Aquaponic Modelling: We believe there is a lack of aquaponic data which meet the scientific standards required to be useful in modelling (i.e. predicting) within acceptable ranges of accuracy the inputs, outputs and variability of aquaponic systems operating under a variety of abiotic and biotic conditions (e.g. climate, water quality, species used, economic circumstances). Virtual or ‘soft’ models, as opposed to quantitative models, are highly theoretical and are constructed with either minimal or without quantitative data and therefore rely primarily on assumptions and questionable numerical values to drive decision frameworks. Although virtual models are easier to construct than their mathematically derived counterparts, this benefit comes at the expense of robustness and accuracy of the modelling tool because models are only as good as the quantity and quality of data used to build them. If investors choose to use modelling tools to aid in the development or management of aquaponic systems, we believe it is imperative to evaluate the underlying data sources from which the model is constructed (if any) to assess their usefulness prior to investment.

Skill Sets: Most potential aquaponic investors are not highly skilled in both aquaculture and hydroponics and the integration of the technologies. Hydrologically linking aquaculture to hydroponics introduces a host of biological, physical and chemical dynamics which constantly interact (synergistically and antagonistically) at various system levels. Because of this, standard pitfalls associated within stand-alone aquaculture and hydroponics now become more complicated, which invokes further demand upon the practitioner to increase skill level and possibly investment (by way of training, and ongoing consultation), or suffer the possible consequences of reduced productivity or system failure.

Commercial Viability: A number of commercial aquaponic systems (of differing designs) we have visited and/or have first-hand knowledge of in Australia and abroad are not commercially viable as stand-alone businesses, but are supported by collateral commercial ventures, federal-state-community grants, and/or volunteer or subsidised labour. Currently, the inability of commercial aquaponic enterprises to become and remain independently financially viable appears to be the rule rather than the exception.

Aquaculture Feeds: The price of commercial fish feed containing high percentages of fish product is increasing due to the depletion of natural resources and rising costs associated with manufacture and distribution. If this trend continues, profit margins of aquaponic and aquaculture businesses could suffer as long as they remain dependent on those commercial feeds.

Parasites: Control of parasitic infestation in plants and infection in fish using proven treatments and medications can cross-contaminate between fish and plant components in systems that follow an in-line recirculation design. Aside from issues of plant and animal toxicity, the loss of an organic certification (or chemical-free brand) could result. However, it should be noted that it is normal for parasites to be present in diverse ecosystems, and reside within their hosts, in numbers that cause nominal impacts. Also, biodiversity within systems may help guard against explosions in parasite populations through bio-control mechanisms, although this aspect of parasitology has yet to be evaluated sufficiently within aquaponic systems.

Kit Systems: Purchasing small-scale, ready-made aquaponic kit systems from reputable distributors may be a practical choice because kit systems are fast, easy, and can circumvent common design pit-falls and wasting money and time ‘re-inventing the wheel’. However, on the down-side, aquaponic kits are more expensive than DIY systems, may be designed to keep customers dependent on collateral support products and services, and most importantly, detract from the critical knowledge that can be gained from building and managing aquaponic systems designed to custom specifications. For those with the skill and knowledge required to build aquaponic systems, the essential hardware is readily available from a range of local hardware stores to specialist aquaculture, hydroponic and aquaponic distributors. Furthermore, most of what is known about building and managing aquaponic systems can be accessed via aquaculture, hydroponic, aquaponic and collateral information sources (e.g. academic journals, trade magazines, training courses, and internet forums). Hence, for those wishing to design and construct small-scale systems, there are ample resources available to them without having to pay consultant fees or for ready-made aquaponic systems to support their efforts.

Rooftop Systems: Recently, the potential for rooftop aquaponic systems has been given attention by several media sources, although the authors of this discussion are not aware of any existing rooftop aquaponic systems, or for that matter, the existence of rooftop hydroponic systems of commercial scale that are economically viable. Investigations undertaken by the authors (2007) regarding constructing an aquaponic/hydroponic system upon a Brisbane shopping centre rooftop suggested that, at that time, the rooftop application did not make economic sense as a stand-alone business when applying a standard investment/return curve over a 5-year period. This was primarily due to the costs of retrofitting the existing rooftop structure to enable the support of production systems.

Additionally, because rooftops upon which commercial production would make sense are located in densely populated urbanised zones, a myriad of hurdles would need to be overcome with respect to zoning, town planning and construction, environmental health and waste management, food production, preparation and distribution, and other operational and logistical challenges. Local authorities will in most instances define rooftop systems as intensive agriculture/aquaculture activities, and therefore changes to governmental policies across multiple departments will be a prerequisite to ‘fitting’ any rooftop system into existing urban development and regulatory frameworks.

However, it is certainly possible to construct rooftop aquaponic systems given enough money, time, interest and collateral support, and we applaud any ‘green’ rooftop project as there are undeniable environmental and social benefits associated with green rooftops of any kind.

Aside from these issues, we encourage continued investigations and practical applications of aquaponic systems of any configuration; especially those systems that aspire toward commercial and research applications. However, this discussion questions whether it is wise to invest in aquaponics as a business venture. From a broader perspective, this discussion questions the ability of those historically involved with the organisation of the Australian aquaponic industry at the national level to rise to the challenge and effectively lead the industry into the future via overcoming the obstacles currently apparent, as well as those on the horizon. However, because the Australian aquaponic industry is still very young, now is the time to impart an industrial code of practice to effectively govern and uphold the reputation of the industry as it evolves.

Finally, we suggest as a preliminary step for those considering investing in aquaponics, that they first consider what consultation services, system design, management tools, operating methods and economic structure best suit their needs, skills, budget and other investor specific conditions prior to investment.

Vermiponics and Vaquaponics

Moving beyond aquaponics, the Integrated Waste Reclamation and Animal-Plant Production Systems project that is underway at the Centre for Plant & Water Science (CQUniversity – Rockhampton) is undertaking a step-wise investigation of methods that aim to generate vermiculture liquor and castings, chemical-free plant produce and live earthworms (that could be used as fish feed) from abattoir paunch and aquaculture waste, water, atmospheric carbon dioxide and sunlight (for the most part) via the use of food web conversions and physical linkages that are practical and technologically straightforward.

The first phase of this investigation centres on vermiponics, which is defined as the integration of vermiculture with hydroponics utilising any design, linkage or methodology. The second phase of this investigation centres on vaquaponics, which is defined as the integration of vermiculture, aquaculture and hydroponics utilising any design, linkage or methodology. Both vermiponics and vaquaponics represent theoretical and technical progress towards sustainable primary production, which if practiced widely, could impart substantial decentralised effects upon waste management, chemical-free food production, soil development and other associated aspects of resource management, environmental stewardship, economics and community health.

Since the inception of the project several vermiponic goals have been met; vaquaponic integrations are planned for late 2008. We intend to report our work in respective academic journals at the conclusion of the research project.

Acknowledgements

We would like to express our gratitude to the Rural Industries Research Development Corporation, Vermicrobe International Pty Ltd, and Ell-grow Systems (by Boxsell Hydroponics Pty Ltd) for their generous support of this project. Additionally, a special thanks to both William ‘Brock’ McDonald (Project Technician) and Elena Churilova (MSc. Candidate) for their on-the-ground technical and logistical support.

About the authors

Dr Brett Roe completed a Ph.D. of Applied Science (2005), in part, by successfully integrating fish and crayfish aquaculture with hydroponic plant production (utilising both in-line recirculating and batch-flow aquaponic designs) that resulted in high quality market-sized products. Dr Roe currently serves as an Honorary Research Fellow with the Centre for Plant & Water Science – CQUniversity Australia. Email: b.roe@cqu.edu.au

Professor David Midmore is a trained crop physiologist with research experience on four continents that extends into systems analysis and integrated approaches to solving issues of resource use and food production. Professor Midmore is the Director of the Centre for Plant & Water Science – CQUniversity Australia.

Together, they are supervising (Midmore) and managing (Roe) the Integrated Waste Reclamation and Animal-Plant Production Systems project located at CQUniversity, Rockhampton, Queensland.

References

Lennard, W. (2007). Aquaponics: What’s the Reality?

Proceedings of the Moraitis Australian Hydroponics & Greenhouse Conference, Tasmania, 24-27 June 2007.

Issue 90: Preliminary observations on simplified NFT

September/October – 2006
Author: Dr Allen Cooper

Growth of the spring cabbage plants was vigorous and very healthy.

Dr ALLEN COOPER demonstrates that water taken up by plant roots is not lost solely from the leaves, but that a large amount is lost from the roots themselves. In this article, the father of NFT documents four scientific firsts, including correlations between day-length and nutrient uptake, between nutrient uptake and the direction of change in day-length, and the photoperiodic relationship with the interaction of day-length and the direction of change in day-length.

At the age of 83 I do not have many years left in which to complete the development of a cheap, simple form of NFT. I am therefore publishing, while there is still time, the information that I obtain as soon as I obtain it in the hope that if I do not have the time left to complete the work, someone may have become sufficiently interested to finish the job. It may be an imprudent course of action but I know that I shall not live to regret it.

It is well established that plants do not grow sufficiently well in a static nutrient solution to produce a crop. Even bubbling oxygen into static nutrient solution is not sufficient to ensure the long-term maintenance of plants or good growth. A minimal requirement in water culture is the re-circulation of a sufficiently large total volume of nutrient solution. The simple form of NFT that I am trying to develop requires no electricity to achieve the circulation. The plants themselves provide the motive power.

There is much about the functioning of plants that has never been questioned. There are widely held beliefs that are accepted as being true without ever having been tested. These believed “truths” are sometimes not explicitly stated but are tacitly implied. The very general subject of plant metabolism provides an example. A visit to a cowshed shows that animal metabolism is imperfect. The organs of the cows for excreting the waste products of their metabolism are clearly apparent and the products of excretion are even more apparent. However, it is tacitly implied that plant metabolism is perfect, presumably because the organs of excretion are not apparent and the products of excretion are even less apparent. Another example of the mythology in plant physiology is the belief that roots absorb water and leaves lose it. Like many beliefs with conviction there is an element of truth in this belief but it is not the whole truth.

A critical examination of the spatial growth pattern of Helianthus annulus throws some light on both of the above beliefs. H. annulus is a perennial plant that, as its name implies, grows with the passing of the years in the form of a ring. If a young plant of H. annulus is placed in the bare soil in the centre of the ring it will die. However, if the soil is removed from the centre of the ring and all root material is carefully sieved out of the soil and the soil is thoroughly washed before being replaced in the centre of the ring, then a young plant will grow well in the centre of the ring. A large scale version of this “poisoning” of the soil is provided by the peach tree replant problem in California where it is well known that young peach trees have been grubbed.

Fundamentally, plants are not very different from animals. In the nineteenth century in London when the products of human excretion were separated from one of the main products for ingestion, namely the water supply, mortality decreased dramatically and population growth escalated. This analogy suggests the untested possibility that in both H. annulus and in peach trees the organs of ingestion and the main organs of excretion are the same organs, namely roots.

It is obviously impossible for the volume of soil in which a plant is growing not to have moisture gradients within the volume of the soil. It is reasonable to make the untested suggestion that the roots at the wet end of a moisture gradient absorbs water that contains nutrient while the roots at the dry end of the gradient excrete liquid containing the waste products of metabolism, in other words plant urine. There is no need for an anus because, unlike animals, plants do not ingest solid food. The leaves are ideally situated to handle gaseous ingestion and the excretion of gaseous waste products of metabolism. Thus, in both leaves and roots the same organ may be capable of both ingestion and excretion. The closest analogy in animals is the mouth that is capable of both swallowing and vomiting.

The above suggestions rest on the ability of “wet” roots to absorb liquid and the ability of “dry” roots to exude liquid. To test this hypothesis I set up a horizontal length of roofing gutter closed at both ends, and beside it and touching it a very slightly sloping adjacent gutter open at one end. The open end was sited above a bucket. Spring cabbage plants were propagated in pots filled with soil until there was sufficient root growth to enable the mass of roots and soil to be slit vertically with a knife from the base upwards to provide a plant with a root system divided into two parts. The plants were placed astride the touching gutters so that one half of the root system was in the horizontal supply gutter that was filled with nutrient solution and the other half was in dry drainage gutter.

The spring cabbage plants were grown outdoors in the simple equipment from September to April inclusive. The volume of nutrient solution in the supply gutter decreased progressively until it was replenished, and a considerable volume of liquid was collected daily in the bucket under the open end of the drainage gutter. There was no doubt that the “wet” roots were absorbing liquid and the “dry” roots were exuding liquid. In this way the plants provided the motive power that achieved the circulation of the nutrient solution without a need for electrical power. Re-circulation could have been achieved by manually emptying the contents of the bucket into the supply gutter. Millennia ago the Egyptians perfected a simple technique for lifting irrigation water that is still in use.

The photograph (please ignore the stone trough; it was too heavy for me to move) shows that the growth of the spring cabbage plants was vigorous and very healthy, suggesting that the plants had benefited from being provided with a dining room separated from their lavatory. Like the Victorian Londoners and H. annulus, they seemed to thrive when not forced to ingest waste products of metabolism. However, this is an untested concept of plant mythology that was fashionable only until the nineteenth century when the work of the German chemists led to the founding of the artificial fertilizer industry and created the resulting increases in crop yields. It is a concept that has remained unfashionable ever since and has been little examined.

Correlation between day-length and nutrient uptake
Another item of plant mythology is the belief that some aspects of plant growth and development are controlled by day-length per se. An enormous amount of work has been done on the influence of day-length on flowering despite the fact that flowering provides a very limited assessment of the influence of day-length on the physiology of plant growth and development because flowering is a fairly discrete response and its progress is difficult to follow without destructive sampling. What is required for study is, firstly, a response to day-length that is continuous and, secondly, a non-destructive method of measuring the response continuously or, at least, daily.

The work that has been done on the response of flowering to day-length has been done in constant day-lengths. In most of the world constant day-lengths do not occur but, despite this the myth has arisen that the same response to day-length obtained in constant day-lengths will apply in day-lengths that are increasing or decreasing. In other words, the response to day-length will be the same in an increasing day-length as in a decreasing day-length. The validity of the assumption has never been tested. The mythology would be in trouble if it were found that plants do not respond to day-length per se but to the interaction between day-length and the direction of change in day-length.

In order to ensure good plant growth I concerned myself with changes in the concentration of the nutrient solution and the maintaining of concentrations that were favourable to plant growth. Consequently, detailed data were obtained daily on the changes in concentration to decide whether to add water or nutrient solution to the supply gutter. The electrical conductivity of the liquid in the supply channel and of the liquid draining from the drainage channel was measured daily. These data are shown in Diagram 1 as the reduction in the cF of the liquid in the drainage channel relative to that of the liquid in the supply channel. Although the electrical conductivity of the liquid in the drainage channel would be increased by the excretion of any waste products of metabolism, and reduction in the cF of the liquid in the drainage channel relative to the cF of the liquid in the supply channel would provide a measure of nutrient uptake.

To eliminate any short-term fluctuations so that the long-term trend could be seen clearly, the data in Diagram 1 are for 10-day means plotted against the time of year. There was no significance in using 10-day means; it merely made the arithmetic easier. The data show that from late September to early November (i.e. from A to B) nutrient uptake decreased, whereas from early November to mid-December (i.e. from B to C) it increased. In mid-December a pronounced discontinuity occurred (i.e. between C and D) when the highest recorded uptake was followed by a very low value. From late December to mid-February (i.e. from D to E) nutrient uptake increased. The subsequent pattern of nutrient uptake (i.e. from E to F) was not well defined.

In looking for an explanation of this seasonal pattern of nutrient uptake, the discontinuity in mid-December is a good starting point. The greatest nutrient uptake occurred on the 8th of December, and the subsequent very low value occurred on the 18th of December. Therefore, an approximate estimate of the date of occurrence of the discontinuity is the 13th of December. What happened about this date?

The data in Diagram 2 suggests a possible answer to the question. In this diagram the day-length experienced by the plants in minutes from sunrise to sunset at the latitude of 50O 45′ N (the location of the experiment) has been plotted from early December to early January. Throughout early December the day-length progressively and regularly decreased, but on the 15th of December the regular daily decline in day-length ceased. The close correspondence between this date and the date of the discontinuity in nutrient uptake suggests the following hypothesis for disproof.

Correlation between nutrient uptake and the direction of change in day-length
There was a biochemical mechanism within plants that was detecting the direction of change in day-length. Immediately the decline in day-length ceased the relation between day-length and nutrient uptake changed. If this were correct then it would follow that plants were responding, not to day-length per se, but to the interaction between day-length and the direction of change in day-length. This possibility is shown in Diagram 3 where the reduction in the electrical conductivity of the liquid from the drainage channel relative to that of the supply channel is plotted against day-length in both decreasing day-lengths. The same lettering of A to F has been used as in Diagram 1. The data obtained in decreasing day-lengths are shown as open circles; the data obtained in increasing day-lengths are shown as solid circles.

It can be seen that in a declining day-length of not less than 564 minutes (the day-length of the 8th of November at the location of the experiment), nutrient uptake decreased as the day-length decreased (A to B). With further decrease in day-length, nutrient uptake increased as the day-length continued to decline (B to C).

In an increasing day-length, nutrient uptake increased (D to E) with increasing day-length until a day-length of 608 minutes was reached (the day-length of the 16th of February at the location). With further increase in day-length (E to F) the relation between nutrient uptake and day-length was not well defined.

It is of interest that the influence of day-length on nutrient uptake between E and F appeared to be less dominant than in other day-length conditions, presumably because other influences were capable of affecting the relationship when the day-length was greater than 608 minutes and was increasing.

Despite this variability of response there appeared to be an optimal day-length of 608 minutes for nutrient uptake by spring cabbage plants when the day length was increasing.

It would be interesting to see if the volume of water lost by the roots is also dependent on the interaction of day-length and the direction of change in day-length. If nutrient uptake is responding to such an interaction, it is reasonable to suggest that excretion would react correspondingly.

The correlation between nutrient uptake and day-length is obvious from the data. What is required is a controlled environment facility in which to determine whether the relation is casual. The use of a divided root system as described earlier would provide a simple, very sensitive method of exploring the responses of root physiology to the environment in a controlled environment research facility. It would provide both a response to day-length that was continuous and a non-destructive method of daily or even continuous sampling. Such an exploration would enable much of the potential of a simplified NFT system to be achieved. It might even make the difference between the long-term operational success and the failure of the simplified form of NFT by obtaining a greater understanding of the influence of the re-absorption of the waste products of metabolism on plant growth and development.

Preliminary indications are that re-absorption hastens the passage from root growth to shoot growth to leaf growth to fruit growth to death, and increases the amount of growth of each stage. The growth regulatory chemical involved might even be identified. The possible potential for the control of development of the part of the plant that is to be marketed is obvious. Applying artificial fertilizers merely increases the growth of the whole plant. Precise targeting would be a commercial advantage.

Surely there is a plant physiologist somewhere who is interested?

For further information contact:
Dr Allen Cooper,
23 Longlands,
Worthing BN14 9NW,
United Kingdom.

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