Re: Proposal to ban soluble fertilisers in WA
We have grave concerns about the consideration being given by the Western Australian Government to ban the use of soluble fertilisers. This would almost certainly have a catastrophic impact upon the local commercial hydroponic industry.
The commercial hydroponic industry
Most greenhouses producing crops use hydroponics, and there is also significant outdoor hydroponic cropping, in particular, lettuce. Many people are aware of hydroponic lettuce and hydroponic tomatoes, which are marketed as such. However, there are other major hydroponic crops marketed only as quality produce, and hence not recognised as hydroponic. Amongst these are virtually all continental and Lebanese cucumbers, herbs, an increasing proportion of capsicum and asian greens, plus virtually all greenhouse cut flowers (roses, chrysanthemums, gerberas, carnations, lisianthus, etc, etc) and a range of smaller crops.
There are no formal government statistics kept for the commercial greenhouse or hydroponic industries. However, we do know that there is a significant commercial hydroponic industry in Western Australia.
Benefits of commercial hydroponics
There are major benefits of hydroponic cropping to the general population, irrespective of the high quality of most hydroponic produce. These relate to the environment.
Hydroponics is an inherently highly water and fertiliser efficient technique. This is because virtually all the water and fertiliser added are used by the plants, leaving almost no wastage. Water usage to produce $100 of product is typically only about 1 kilolitre, or even less, compared to 20 to over 100 kilolitres for soil grown crops. Well managed hydroponic systems have virtually no excess fertiliser and hence do not leach into the environment.
Hydroponics and greenhouse culture increases the incentive to use integrated pest management (IPM). IPM significantly reduces the usage of agricultural chemicals, especially the more severe ones, and increasing numbers of commercial hydroponic growers are going this way.
What is hydroponics?
Hydroponics is 'soilless culture', that is, 'growing plants in systems isolated from the soil, with or without a growing medium, and supplied with all the water and nutrients that the plants require.' The name hydroponics is derived from the Greek words hydros, water, and ponos, labor, hence 'water working'. One of its earlier names was 'solution culture'.
The basis for all hydroponic systems is to dissolve soluble fertilisers to give the full balance of nutrients that the plants require. These are usually dissolved in two concentrated solutions ("A" & "B") which are then manually, or more usually automatically, diluted to working strength and added to the system.
The grower continuously controls the working solution acidity by measuring pH and its strength by measuring electrical conductivity (EC). EC works on the basis of measuring the electrical strength of the nutrient ions in the solution. Nutrient balance is checked and corrected by routine chemical analysis.
Problems with slow release fertilisers
The slow release fertilisers which can be substituted for the soluble fertilisers currently used have the following problems:
* They are, obviously, very slow to dissolve and can never give concentrated solutions. This is because some individual fertilisers contain the combination of nutrients which are kept separated in the A & B concentrates currently used. Automatic control requires the use of concentrates.
* The balance of nutrients available in these fertilisers makes it extremely difficult to obtain the required balance of individual nutrients required by the plants.
* Many the slow release fertilisers do not ionise when dissolved, and hence the basic means of controlling solution strength with EC will no longer work, and there is no alternative.
* Combining these problems indicates that it will be impossible to manage a hydroponic system if soluble fertilisers are banned.
Implications for the commercial hydroponic industry
If this proposal was to go ahead the impact upon the commercial hydroponic industry is very easy to predict - it would cease to operate. The only choice for growers, who couldn't obtain the full range of required soluble fertilisers, would be to give up or return to growing in the soil.
The unlikely option of changing to soil growing would lead to:
* Lower yields and quality,
* Impact of soil diseases and the use of agriculture chemicals to control them,
* Increased use of water and fertiliser together with higher levels of leaching.
* The very likely final result of being unable to compete on quality and price with hydroponic produce from interstate. This would lead to their eventual demise.
Yours sincerely,
Graeme Smith
AHGA President
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