The debate surrounding peat alternatives has dragged on for decades. In the last few years the clamour from environmental groups urging a stop to the use of peat and the ‘degradation’, as they would have it, of peat bogs through commercial exploitation, has reached a high volume. The big retailers and even the government, worried that a lack of action on the green message will impact their fortunes at the cash till or ballot box, have decreed growers and growing media suppliers must use and investigate alternatives to peat.
But the government’s target of a 90 percent reduction in the use of peat by 2010 looks unlikely to be attained. The Growing Media Association’s chairman Catherine Dawson reckons that if the current rate of change in the industry, based on Defra figures, continues, it will be 2026 before that target is reached. One thing is for certain, as Dawson, in charge of R&D at growing media supplier Melcourt, puts it: “The peat issue is not going away. And the government has repeated that there is no prospect of it dropping its 2010 target.”
Over the last three years the GMA and others have developed the Growing Media Initiative, chaired by the HTA’s Tim Briercliffe, with members including bodies like the RHS, RSPB, B&Q, Focus, Homebase, Co-op and representatives from the growing industry, to look into how to accelerate the rate of change on peat alternatives. A certification scheme is planned to be operational before the end of the year for companies working towards peat reduction. The emphasis will be on bagged products in the retail sector but as Dawson says, the very existence of such a move sends a message to government that the industry takes peat reduction seriously and that government need not interfere with more stringent legislation.
Another aspect to the argument is that the Government is investigating the role of peat land as a ‘carbon sink’. Undisturbed peat bogs hold vast quantities of carbon which become mobilised once the peatland is drained and harvested. This aspect is beginning to engage governments in other countries with large peat reserves and could end up having a much bigger influence than that of habitat loss.
Melcourt only sells non-peat materials and therefore it is no surprise that Dawson believes suitable ingredients other than peat are available in quantity. Bark and wood fibre have a long history of use. She says coir is still very much out there but not in big quantities.
Composted green waste, however, has a ‘lot of technical challenges’: pH’s in excess of seven, high soluble salt level and high bulk density. It can be used at levels in the mix of up to 50 percent but most applications restrict use to 30 percent. It can provide a good source of slow release nutrients, is widely available and although consistency of quality is variable it is relatively cheap if sourced locally.
Dawson explains: “Composted green waste must be used judiciously. It can be a very useful ingredient and shouldn’t be discounted. The reality is that a lot of it will find its way into retail composts rather than commercial. When produced properly it’s very much like loam, which a lot of growers are using... generally though, the manufacturers are better placed than growers to source green compost as they have the specialist testing facilities to do all the necessary quality assurance checks.
“Green compost sometimes also has a useful added benefit in that being highly mircrobially active it can suppress the activity of pathogenic microbes.”
The take-up of peat alternatives among growers is somewhat patchy. It is still a minority ingredient compared to peat although some growers - for example one time Grower of the Year category winner Pepperidge Herbs, Lincs - have gone completely peat free. The GMA chairman says that in her experience growers that approach peat alternatives with an open mind and some enthusiasm tend to get on better with it than those that have it ‘foisted on them’.
“My belief is that for the majority of growers a gradual reduction is the best option. They then have time to get used to the new ingredients, to pick what suits them, taking a season or two to trial it. Ask the supplier lots of questions and ask to see the data. It is far easier to do it at your own pace than to have a customer suddenly putting the pressure on. The expertise developed by the manufacturers now makes it so much easier for growers to make the transition. There’s not a single major manufacturer who doesn’t supply alternatives.”
With all the talk about peat alternatives it is sometimes easy to miss the fact that many still have a question mark hanging over them. These questions are not made any easier to answer by the fact that most research into alternatives is done privately and secretly by companies and the results not made publicly available.
The Board for Horticulture’s Sarah Fairhurst, of Porters Horticulture, Merseyside, points out that growers still cannot be sure that a product such as coir is more environmentally viable or sustainable than peat. There is the question of air miles. Coir is imported from countries like India and Sri Lanka. When processed for use as a growing medium coir must be washed, a process that releases salts into water courses, she says.
Porters, which supplies B&Q, has about 11 acres of glass producing plants such as geraniums and New Guinea impatiens.
Fairhurst says: “It’s making sure we have a long-term viable source. We use about 70 percent peat with alternatives such as wood fibre. We can’t go 100 percent yet as we find alternatives very free draining. But we probably do two or three trials a year. We’ve trialled wood fibre, cocoa grit, coir, even sheep’s wool.
“We don’t think green waste is suitable for our type of plants. It’s fine as a soil improver, conditioner or mulch but we need a reliable source and more data. I would like the government to provide us with an analysis of peat and alternatives. Growers don’t know what they can and can’t use. We’ve got to look at this as a business. I would be quite happy to use a peat alternative but we must have quality, quantity and consistency. A lot of people have put money into this. But I don’t think we as an industry are there yet.”
Along with those problems - and a little at variance with Catherine Dawson - Sarah Fairhurst says that in her experience the use of alternatives means a rise in costs. But neither customers nor consumers seem willing to pay more for their flowers.
This is a theme picked up by Jonathon Cox, managing director of Cumbria-based growing media supplier Humax. He says there is very little opportunity for growers to increase their selling price despite peat alternatives adding 10-12 percent to their production costs.
The biggest issue, he says, is transport. As we have mentioned, coir comes from the Far East. The cost of composted green waste, he says, is double that of peat. Peat has a lower bulk density than green waste compost, which is 20-30 percent heavier. Fuel costs for transporting the composted green waste are therefore more.
Humax, which has drawn from the same peat bog since 1883, has been producing peat alternatives such as recycled green waste and coir for the best part of eight years but, says Cox, very few of his customers are using it.
“In general terms there is no single product across the board comparable to peat for all uses. Green waste consistency varies, for instance the nutrient content. Peat usually has no variation whatsoever. That’s the beauty of it. Our policy for peat alternatives is that if you can add an alternative to your peat-based composts for a specific use we have no hesitation in doing so. But you can’t simply replace peat with a product that’s not performing well - there’s too many livelihoods depending on quality of products. ‘Peat-free’ barely registers on our market share chart.”
Like most, if not all, of the major suppliers Humax does not produce any specific peat alternative product. It creates bespoke formulations to suit individual growers’ needs.
He is fairly sanguine about the target of 90 percent reduction by 2010 and the unlikelihood of the industry reaching it. When it was first mooted it was described as an ‘aspirational target’. Despite various organisations trying to make it a formal figure Jonathon Cox believes Defra is realistic enough to see that having reached a 45 percent reduction by 2006 in the retail market, the industry is moving in the right direction.
He says: “As for the professional market, unless there is some scope for an increase in costs for growers I really think things are going to remain static. We generally find most of our growers are being asked to reduce their prices.”
Bulrush’s Neil Bragg agrees that the use of peat alternatives necessitates production cost rises which put growers in a vulnerable position with their customers. The customers, however, put pressure on their suppliers to go the peat reduction route.
“Growers want consistency in their growing media. But to get consistency you have to pay because you’re adding value to your substrates. The question is: is anybody willing to pay the cost of that?”
“But there’s no mass public opinion on peat reduction. The government only says it something it would like to see and there’s no financial penalty,” he says.
Some HDC projects
HNS 127 Waste into rooting media
The aims of this project were to identify at least three (technically and economically) suitable materials for commercial development for HNS growing media production (finished pots and liners of herbaceous perennials and woody ornamentals).
Identify materials with the potential to replace, in total, 40 percent of the peat used by the UK nursery stock industry.
This project was funded by GrantScape through the Landfill Communities Fund, made possible by donations provided by Waste Recycling Group Limited. The HDC made an enabling 10 percent Third Party Contribution to the project.
After a preliminary screening of waste materials based on physical and chemical characteristics, wastes from different sectors of the paper industry along with carpet shearing waste were considered to have most potential as peat substitutes in HNS growing media. Three types of paper wastes were used:
‘crumb’ waste from recycled paper production,
‘pulp’ waste from virgin paper production;
‘compacter’ waste from recycled cardboard production.
The project identified waste materials that can be used beneficially to substitute peat in growing media for a range of hardy ornamental nursery stock species. Carpet shearing wastes improved the growth of a range of herbaceous perennials and woody ornamentals grown in finished pots and 9cm liners. Composted paper wastes improved the growth and flowering on a range of herbaceous perennials.
The use of wastes from paper and carpet production in growing media for HNS has the potential to improve profitability in several ways: by improving the growth, quality and flowering of a range of herbaceous perennials and woody ornamentals in finished pots and liners; lowering costs by reducing the need for controlled release fertilisers and lime in growing media; reducing the incidence of soil-borne diseases caused by pathogens such as Phytophthora and Pythium species through the incorporation of composted paper wastes in growing media.
This aspect was not investigated in this project, but is supported by a significant amount of research into disease suppression using composts, the report concluded.
It was also said to improve the environmental image of the HNS industry by reducing peat consumption and reducing waste landfilling of other industries.
CP 50 Producing a horticultural growing media peat replacement through the retention of plant structure in composted food-processing waste ‘COMPEAT’
The aim of this proposal is to provide the scientific knowledge necessary to control the production of high-quality horticultural growing media through the retention of plant structure in composted food-processing wastes from a wide variety of traceable sources.
The current supply of peat is under threat as a result of various EU directives, particularly the Wetland Habitats Directive. In addition, targets to reduce biowaste (eg. landfill directive) have encouraged National Government to set aspirational targets for reducing peat use in Horticulture, the hope being that the reduction will be addressed by the use of the composted materials, the report explains.
Although commercial composting produces a low quality, poorly structured product, controlled composting of food processing waste could provide a potentially suitable safe, traceable and sustainable alternative source of growing media. This would also help the food industry to address the increasing difficulties associated with co-product disposal.
The study will assess the potential to develop new and novel materials as growing media which will both prove to be reliable, consistent and predictable for growers in key horticultural sectors. Variability in peat results in up to 10 percent waste during media manufacture. New, predictable and uniform compost-based growing media could create an annual benefit of £6-12 million (wholesale) across the whole industry.
CP 41 - A review of peat usage and alternatives for commercial plant production in the UK
The latest assessment commissioned by Defra is entitled ‘Monitoring of peat and alternative products for growing media and soil improvers in the UK 2005’ and is in the latter stages of preparation by Enviros Consulting and ADAS. Its primary purpose is to establish if the 40 percent replacement target by 2005 has been achieved.
The report observes that the target is generic and covers all uses in all markets and is not applicable to each and every sector. Once published later this year it will be used as a basis for a Defra led discussion with stakeholders to drive and target the process of peat reduction. Further assessments are scheduled for 2007, 2009 and 2010.
growing media statistics
Growing media used in plant production in the UK are made principally in the UK.
In 2005, the volume of growing media supplied to professionals by major manufacturers plus that mixed on the nursery was estimated to be over 1.25M m3, but for retail use the figure was almost 2.4M cu m. Peat comprised 86 percent of professional media and 76 percent of retail media giving an overall peat usage of 79 percent across the two markets, down from 92 percent in 2001 (ODPM, 2002)
Peat usage in professional horticulture is projected to continue to decline over the coming years. Bark will remain the predominant diluent followed by wood-derived materials. Coir will be used in some niche applications but Composted Green Waste use will remain minimal. In the vegetable transplant and mushroom casing sectors peat use will remain at around 90 percent.
In the retail sector peat usage is expected to fall to 65 percent in 2007 and to 55 percent by 2010.
In the professional market, nursery stock was the largest sector in 2005 (32 percent) followed by bedding and pot plants. These three sectors accounted for 79 percent of all media and 76 percent of peat usage by professionals.
By 2010 some predictions state that less than 40 percent replacement of peat is likely in the whole growing media market. On this basis, assuming the growing media and soil improver (GM & SI) markets to be the same proportions as in 2001 and that the latter is entirely peat-free; it is possible to estimate that the degree of peat replacement by 2010 in the combined GM & SI markets will (realistically) be in the order of 60 percent. To achieve the government aspiration of 90 percent peat reduction would require the growing media suppliers to reduce the peat content of professional and retail products by 85 percent overall - more than twice that which is anticipated in some quarters.
There is a large amount of technical information in the public domain and many non-peat substrates have been and continue to be investigated as growing media constituents throughout the world. These include barks (softwood, hardwood, cork oak), sawdust, industrial wood fibres, charcoal, wood wastes, fibre boards, composted green and other wastes, composted animal and human manures, sludges (including paper, and soy scrap) coir fibre and dust, food wastes (rice hulls, grape marc, palm oil fruit bunches, and fruit and vegetable waste), Miscanthus and seagrass, minerals (rock wool, pumice, perlite, vermiculite) and synthetic foams; and most of these have been used successfully as partial peat replacements or, especially in combinations, as peat-free media.
The exploitation of peat and numerous other substrates in growing media for horticultural production in any one country is essentially governed by cost, performance, and geographical, socio-economic and environmental factors rather than the results of research elsewhere.
In countries in northern Europe (such as Finland, Sweden and the Baltic States where there are still vast reserves of horticultural grade sphagnum peat) and in other countries in more southerly latitudes that were once self-sufficient in sphagnum peat (such as Holland, Denmark, Germany and the UK) peat remains the substrate of choice among professional growers and manufacturers for both technical and commercial reasons. In other countries (such as Belgium and France, where for geographical reasons, indigenous peat has always been of limited quality and availability) the horticultural industries which have developed in the last 50 years still use imported sphagnum peat or ready-made growing media from those countries where supplies were freely available, although the use of indigenous organic (waste) materials derived from bark and woody materials etc. is increasing.
It is widely recognised that to sustain a modern, competitive, European commercial horticultural industry, sphagnum peat is critical because no other material combines as many favourable physical, chemical and biological properties at an economic price. This peat is the most versatile, most reliable, most used and most traded material in the production of growing media and the performance of the horticultural industry is thoroughly dependent on growing media based upon it.
While it has been reported that many organic materials have been used successfully, there are recurring concerns about consistency, stability, nitrogen lock-up and the need to modify feeding and watering regimes to take account of the nature of the materials used, together with concerns about material variability, hygiene and the carry over of plant diseases.
The UK is alone in having a government policy of very significantly reducing the use of peat in horticulture and a programme of monitoring the level of its replacement. However, for the last 10 years there has been little publicly funded R&D to support government-endorsed peat replacement targets and to address the technical and horticultural issues through programmes based on scientific and commercial principles.
Since 2001 there has been some government-funded investment in the testing and promotion of composted green waste (CGW) by the Waste and Resources Action Programme; but this has been driven by the need to reduce landfill and has so far not led to any great uptake of this material in professional horticulture by sceptical growers and cautious manufacturers mindful of its variability, technical weaknesses, performance limitations and product liability concerns. This situation is mirrored in Holland, where RHP does not include CGW in any of their recommendations for professional growing media.
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