Types of Hydroponic Systems for Berry Production.

Hydroponic Systems Adopted by Intensive Berry Cultivation

There are 2 basic types of hydroponic systems – ‘open’ and ‘closed’ systems.  The open hydroponic system means that the nutrient solution is distributed into the system and what the plants do not uptake is run off and not recirculated e.g. free drainage system.  The closed system is the opposite with the nutrient solution being recycled and retained within the system e.g. recirculating system.   It must be noted that strawberries and rubus are especially susceptible to root borne diseases and that is why the majority of growers select the open system because they afraid of recirculating diseases through the irrigation system.  This is unfounded as a good closed irrigation system should have adequate sterilization to prevent diseases being passed through the nutrient solution. Within these 2 types of hydroponic systems there are variations of techniques of how the water and nutrients are delivered to the berries.    Below are some of the different systems:

 

 Nutrient Flow Technique / Aeroponics

 

strawberry production in PVC pipes in Port MacquarieFigure 36 Strawberry production in PVC pipes with Aeroponic System. (Source: W Mann NSW July 2013)

 

Drip Tape or Trickle Feed

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Figure 37 Drip tape under black plastic matting in raspberry production. (Source: N. Mann Spain March 2015)

This is the most common hydroponic system where the fertigation is fed through drip tape which is laid on the bed and usually under the mulch material.   In some countries this is referred to trickle-feed especially in USA – it is cheap and effective but in warmer climates it is advised to have it below the mulch as water can be lost to evaporation.   In New Zealand it was observed drip tape being as far as 1m from the plant on either side for mature blueberry bushes as this berry has wide spreading shallow roots.  (Peach, 2014)

Individual Drippers

NH blueberry pot Netherlands

Figure 38 Northern Highbush Blueberries growing in black pots and blended media with 4 drippers. (Source: N Mann The Netherlands March 2015)

Individual drippers are the most common form of delivery of fertigation in containerized hydroponic berry production.  The better performing berry crops observed around the globe had more than one dripper for pot and ideally 4 – to disperse the water and nutrients evenly for even spread of roots and even uptake up water and nutrients.  In colder climates the black drippers are more common and in warmer climates the white micro-tubing is used to deliver the feed mix – as it reflects the light and so in turn keeps the temperature down of the incoming fertilization and irrigation.

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Figure 39 Coir slabs growing strawberries with white drippers. (Source: N. Mann The Netherlands March 2015)

Run to Waste

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Figure 40 Raspberry in black pots elevated on polystyrene in a run to waste system. (Source: N. Mann The Netherlands March 2015)

It was surprising to see so many projects around the world with run-to-waste irrigation systems especially in the low-tech hydroponic berry growing systems.  There are a couple of reasons why this happens :- water is cheap and plentiful, there is no infrastructure in place to capture and recycle the water, growers are growing to very little drainage (i.e. not watering for the normal 15-40% return), growers are concerned of spreading root pathogens through a recycling system so will not adopt this system, cost of setting up a recirculating system.  Going forward this will have to change as water is a precious and valuable source and cannot be wasted, regulations will also prohibit leachate which is currently occurring, growers will become aware of the massive savings of recycling and re-using the nutrients.  It is far easier to manager EC in a closed irrigation system than an open flow system.  (Donnan, 2015)

Recycling of Water and Nutrients in Table-tops and Suspended Gutters

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Figure 41 Suspended gutters growing strawberries in troughs. (Source: N Mann The Netherlands March 2015)

The more sophisticated the growing system the more sophisticated the irrigation, fertigation and control system that operates it.  Closed irrigation systems are nothing new and common place in most greenhouse growing systems and becoming increasingly embraced by berry growers. All run off from the plants is collected, put through a sterilization system, nutrients and water maybe adjusted slightly depending on the plants needs and the climatic conditions within the greenhouse and then it is re-applied again and again with no waste. The only loss in the system is what the plants are taking up and making in vegetation or fruit. This system provides enormous savings for water and fertilizers use.  (Donnan, 2015)

Raised beds

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Figure 42 Raised beds of sand growing Strawberries. (Source: N Mann Spain March 2015)

Raised beds are the cheapest and most common form of hydroponic berry production.  The soil is treated like a substrate and all water and nutrients are applied regardless of what is naturally occurring or available in the soil beneath the crop.  It is a more complicated growing system as the soil in a field may vary greatly from one area to another yet the fertigation is all the same which can create uneven plant development, health and yield.  Although a cheaper option of growing it definitely has its limitations especially that it requires sterilization at the end of each crop which is tedious and expensive and also because the sterilization kills everything in the soil (good and bad pathogens) if the berry crop does get a bad soil borne disease like Phytophthora fragariae var. rubi there is nothing in the soil to slow down it’s progress and it can wipe out an entire strawberry or raspberry crop in days.  (Eccles, 2014)

 

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