Soil-less production predominates

Article taken from the Berry Yearbook & Buyers Guide

The past decade has seen a seismic shift in the way UK strawberry and raspberry crops are grown, the majority now relying on soil-less production systems.  This trend has been driven by various factors including problems associated with pests and diseases as well as planning issues.  Another factor has been the challenge of attracting sufficient seasonal labour to work in field grown crops and the need to reduce harvesting costs.

With the loss of methyl bromide soil sterilants and with the option to rotate crops becoming increasing difficult due to polytunnels planning restrictions, the industry was forced to think again moving production from soil, to peat and now largely to coir.  The transition to soil-less cultivation methods and in many cases table top growing systems has brought new challenges as well as many benefits.

Dr Jim Smith, technical manager at Everris, estimates 80% of containerized strawberries are current grown in coir, which is widely used due to its excellent growing properties and its sustainability, producing high yields and good quality crops.

“Coir is a relatively consistent material,” he says.  “It takes in water readily and drains reasonably well.  Plants root very freely provided the conductivity is kept low and it has some buffering capacity for fertiliser, though less than peat.”

More stable than peat, water management is easier with coir and there is the potential for higher production levels.  Unlike peat coir-based substrates can be used for two or more seasons helping to improve financial viability.

Coir comes from the pith in the outer shell of the coconut seed.  While the fibre is used for making ropes, mattresses and mats, the pith is dried in the sun, screened to take out the dust and compressed in blocks/slabs/discs etc.  Where there is no shortage of coir, the best quality is limited due to the restricted manufacturing facilities in Sri Lanka and India.

Growing in tropical water, coconut palms are very salt tolerant, with the potassium and sodium salts stored in the plant cells.

“Quality has to be checked as if the coir is not prepared properly by the manufacturer it may have a high sodium  chloride value, which pushes up the conductively and therefore restricts early fertigation,” explains Jim Smith.  “This can be overcome by flushing with a calcium nitrate solution to displace the sodium and then flushing with clean water to get rid of any excess fertiliser.  Potentially this could cause pollution so the system needs managing.

“High quality coir is buffered to remove most of the sodium chloride providing a low nutrient, low conductively product to start the crop going and allowing flexibility in fertigation.”

Strawberry grow bags (modules) are simply laid out in their final positions and wet up.  Coir expands when water is added and fills the slab sleeve.  The slabs can then be planted and appropriate fertigation applied.

A leader in this field, Botanicoir recently launched Precision Plus grow bags containing a blend of different particle sizes to ensure excellent drainage, air filled porosity and water / nutrient holding capacity – as well as long-lasting structural integrity.

While the ‘Precision’ relates to the very specific grading and buffering techniques, the ‘Plus’ relates to the stable structure and the longer durability of the product.  Accordingly to Botanicoir, as long as the bag remains disease free it can last up to four season – which can only be achieved with a high quality product.

Good drainage is important for root development.  According to Mark Davies of Agrovista, Botanicoir Precision Plus is eminently steerable allowing growers to quickly react, increasing or decreasing moisture content, pH or Electrical Conductivity (EC) level.  Especially useful during more stressful periods of crop growth, this helps maximise saleable yield and quality and reduce cost.

Precision Plus grow bags can be supplied up to 120cm long (width and height as required) and with pre-cut planting, dripper and drainage holes as needed.  Stringent, QC procedures at the factory ensure EC, pH, calcium, sodium, boron, magnesium, chloride, silicon and potassium levels stay within the recommended range for strawberry cultivation in coir.

For trough systems several manufacturers supply naked slabs or briquettes.  Botanicoir’s contain the Precision Plus strawberry mix and are subjected to the same strict QC.  With these products flexibility is increased as the numbers of plants per metre can be changed year on year, and the troughs can be moved around without disturbing plant rooting.

Particularly suited to raspberry, blueberry and blackberry growers, Cocogreen and others offer a range of coir disks and blocks for use in rigid plastic container systems. In addition, open top containers are also available from some suppliers.

For growing systems relying on troughs, buckets or pots coir can be purchased ready for use from a growing media manufacturer.  Having arrived in the UK in blocks, these are reconstituted by breaking them up and adding water, lime and fertiliser.  The finished product can then be purchased as bulk, bulk bags, probales or 75 litre bags from growing media manufacturers such as Everiss, Sinclair, Horticulture and Legro Potground.

“Coir comes in one structure which is relatively fine.  Coarser material can only be achieved by adding other material such as peat,” explains Jim Smith.  “Cheaper than coir, peat dominates the soft fruit propagation market although it, has become a minority growing media product in the sector.”  However, looking to the future he says there is interest in blending coir and peat as this appears to improve yield.

Everris has worked with coir for many years, primarily importing and rehydrating coir blocks to produce material for inclusion in its Levington peat reduced, growing media mixes. Orginally destined solely for the UK ornamentals sector, Everris has recently responded to demand expanding its coir processing operations to supply the soft fruit sector.

“Using professional grade coir, the blocks are processed through our designated bulk re-hydration facilities at Nutberry, in Dumfriesshire,” says Scott Garnett, speciality agricultural manager at Everris.  “This means we have complete control over the process ensuring fruit growers received a consistent product.

“During the recent major upgrade of our facilities, the in-house engineering team has designed and built a bespoke coir rehydration facility.  As well as pear-reduced mixes, Everris now supply excellent quality coir stand alone substrate for the UK soft fruit sector.

Guide to coir products available from a number of leading suppliers

Manufacturer / Supplier

Grow bags / modules

Naked Slabs / Briquettes

Discs

Open Top Containers / Pop Up bags

Semi Compressed in bags

Bulk

Botanicoir

 

Bullrush Horticulture

 

 

 

Cocogreen UK

Everris

 

 

 

 

Horticultural Coir

 

 

Legro Potground

 

Sinclair

 

 

 

 

 

 

11 February 2014

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