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8 Review of scientific research on organic farming and growing systems - implications for Scotland

Current and recent organic farming research projects - United Kingdom

8.1 Research projects have been collated for the UK as a whole, rather than by individual country. This is because many projects are collaborative, and involve contractors from England, Scotland and/or Wales. Also, Scottish funders commission work with English contractors, and vice versa.

Scope of the data

8.2 The list is based on that collated in 2003 for Defra project OF0338. Projects active in January 2000 and later are included. Only projects dealing specifically with organic food and farming are included. There is a wealth of projects on non-organic systems with relevance to organic farming but their collation is outwith the scope of this study and would be better tackled on a specific topic basis. Some studies funded by Defra have already done this (e.g. OF0178).

8.3 Errors and omissions in the OF0338 list have been corrected, and more recent projects added to the list. Each project is listed only once against the name of the lead contractor. The projects are listed in alphabetical order of lead contractor. Related websites have been listed only where they are project-specific. Key words allow the electronic version to be searched.

8.4 The quality of accessible data on current projects varies considerably. Of the main funders, Defra have relatively comprehensive details of the objectives of most projects available on-line, but it was difficult to find information on most SEERAD-funded projects, other than the title and contractor.

8.5 Improved on-line access to details of current and recent work would help funders, end-users and research contractors to better direct work and use the results. Contractors do provide some results, but can be constrained in what they can offer, due to the need to get funder approval. Better access to summaries of project results on funders' websites would help both contractors preparing bids and end users to apply the results.

Analysis of the data

8.6 The list includes 160 projects (see Appendix). Most projects cover more than one main topic. The split of projects by topic shows a predominance on crops and horticulture, with over half of the total number showing these as key topics. This is followed by economics with 30 projects, livestock with 29, and soils & crop nutrition with 14.

8.7 It is interesting to note that only 12 projects had a substantial environmental component (only one in Scotland), given that this is the main reason for EU support for organic conversion and the extent of the uncertainties surrounding environmental benefit, particularly in extensive systems. Work in this area can be expensive and of extended duration, but in the absence of definitive data, doubts will remain that organic conversion is the best route to gaining environmental benefit, particularly in the hills.

8.8 Only 7 projects specifically targeted knowledge transfer, but this underestimates the true level of activity, and is probably not of undue concern, as most funders now require clear knowledge transfer in project plans.

8.9 Marketing is low down the scale with only three projects - the DefraOrganic Grain LINK study, SEERAD project SAC/262/00 and the EU funded OMIARID project. However, other initiatives on marketing exist, that are not classed as research, for example the SEERAD funded "Guide to the Marketing of Organic Food" written by SAC. However, market conditions have changed rapidly in the last four years, as organic supply has outstripped demand in many sectors. Some of the earlier marketing studies may need revision to be relevant to current economic conditions.

8.10 The majority of projects are Government funded, either by UK devolved governments or by the EU. Substantial industry funding is limited, and often linked to marketing objectives, rather than a desire to expand knowledge or scientific understanding. The specialist organic industry is not cash-rich, especially in the current market conditions. This means that they have few funds available for research. This is confirmed by difficulties in getting industry partners for the current Organic LINK programme.

Relevance of projects to Scottish conditions

8.11 Organic farming systems work to the same biological principles irrespective of geographical or political boundaries. Therefore, unless dealing with crops or livestock not found in Scotland (e.g. sugar beet), or a specific local initiative (e.g. the Bedfordshire County Council study), there will be some, if not considerable relevance in the majority of these projects, to Scottish conditions.

8.12 We made the initial assumption that all work funded by SEERAD is relevant to Scotland. In addition to work done in Scotland, or funded by SEERAD elsewhere, the following are of particular relevance to Scottish organic farming systems:

• the upland beef and sheep system research at ADAS Redesdale in Northumberland. This represents the dominant land use in Scottish organic farming and there is no comparable long-term study in Scotland. Redesdale is 10 miles south of the Border, and includes farms in Scotland in its linked-farm studies
• the Defra-funded participative research project ( OF0315) on weed control led by HDRA. Stakeholders have directed effort principally at perennial weeds such as docks and thistles. Control of these weeds was raised at all producer consultation meetings as key technical issue. The HDRA project includes a useful website that includes basic weed biology and control information. Much will be relevant to Scottish conditions and could be used as an aid by the advisory services. This study should also help identify areas for further research
• a range of studies funded by the Welsh Assembly Government and the Countryside Council for Wales relevant to upland livestock farming. The farm structure and environment is different in Wales, but these studies could be relevant to some aspects of the Scottish situation.

8.13 Comment was made during our consultation with researchers that the current and recent past programme of organic farming research funded by SEERAD was addressing fundamental science issues rather than the practical problems facing producers. This casts some doubt on our initial assumption that research funded by SEERAD is all of relevance to organic farming in Scotland. However, SEERAD's objective in funding research is not clear from the work funded to date. It includes soil fertility, nutrient cycling and mathematical modelling of arable annual weed populations. This is not answering the producer issues that we have identified. Neither is environmental impact, the reason for government support, or food quality, the reason given by most consumers for the purchase of organic food, obvious drivers for the research. It was pointed out to us that, in contrast, the Defra programme has been more practical and near-market and has resulted in outputs more useful to producers. Our consultations suggest that practical near market research is currently of higher priority to support producers in Scotland, and research to determine the true environmental impact organic systems, particularly hill and upland systems, is needed. The current programme is not meeting either of these needs well, but rather seems to revolve around the interests and specialisms of key organic farming research groups in Scotland.

Related work in other European countries

8.14 A review of organic research across the EU and other neighbouring European States was completed for Defra in 2000 ( OF0171). This included the provision of a searchable database of projects which is available on-line at http://organic.adas.co.uk/.

8.15 Although done four years ago, this remains the only recent comprehensive survey of activity across Europe. Given the relatively slow rate of change in priorities, this is probably still a reasonable picture of current effort. However, it would be enormously helpful to researchers, funders, policy makers and end users if funding could be found to maintain and update such a database. Perhaps this could be done under the currently discussions on a European Organic Action Plan.

8.16 Defra's priority was to examine northern and central European research programmes i.e. those likely to have the greatest relevance for the UK. This included France, Belgium, Holland, Switzerland, France, Germany, Austria, Norway, Sweden, Finland, Spain, Portugal, Luxembourg, Denmark, and Ireland.

8.17 The review concentrated on organic research rather than "low input", or 'integrated' conventional farming systems. Animal health and disease control projects were excluded as these were covered by a concurrent review of animal health and disease control in organic systems by the Veterinary Economics and Epidemiology Unit ( VEERU) at Reading University ( OF0172).

Analysis of the data

8.18 A total of 636 projects were identified (excluding UK). Research in organic agriculture was being conducted in most European countries, with the greatest activity in Germany, Austria, Switzerland, Denmark, Sweden, Norway and Finland. In Southern Europe, there was relatively little research. Avenues followed tend to reflect cropping patterns (e.g. olives, citrus fruits, wine, early vegetables) and particular problems of the Mediterranean region (e.g. maintenance of soil organic matter).

8.19 The projects were dominated by crops (30%), followed by livestock (15%), soil fertility (10%), fruit (6%), environmental impact (5%), vegetables (5%) and food quality (4.5%). The very low proportion of effort into environmental impact, the main reason for EU support, and food quality, the driver for most consumers, is noteworthy. Studies on whole systems were a low proportion of the total, probably mainly a reflection of the cost and long timescale of these studies not fitting well with the general short term funding processes of most funders in the EU.

Applicability of results

8.20 Many aspects of research carried out in Denmark, Germany, Austria, and Northern France have potential application in Scotland, for example in, cultivations, soil fertility, cropping, nutrient management systems, livestock production, and horticulture. Elements of Swedish, Norwegian and Finnish work, particularly related to livestock husbandry and horticulture will also be relevant. Results from these studies should be considered by funders and researchers planning new work.

8.21 In Southern Europe, the research avenues followed tended to reflect cropping patterns and particular problems of the Mediterranean region. Compared with the UK, the contrast in climate, farming and cropping patterns is large. In these areas the most rapid expansion has been in permanent crops and stockless systems, which can pose significant problems for sustainability under semi-arid conditions. However, these studies may become more relevant depending on the rate of climate change in the UK.

8.22 Much of the research programme was at an applied level, designed to tackle specific technical issues. Many of the problems of organic agriculture in northern Europe are common to the UK - rotation design, perennial weed control, pathogen control etc. However, there was a general understanding between researchers that to make progress we need to study underlying mechanisms such as the relationships between soil, plants and mycorrhiza. This provides good opportunities for the combination of fundamental and applied research.

8.23 Research into dairying, pig production and poultry systems is undertaken, but to date there is still only limited beef and sheep research on continental Europe.

8.24 At the time research projects were only at an early stage of development for long-term goals such as the breeding of plants for organic systems, or selective livestock breeding for organic systems. However, recently more emphasis is being placed on some of these aspects.

8.25 It is generally recognised that by its nature, research into organic systems, for example rotation design, requires evaluation over a significant time period. This can cause problems regarding the stability of research funding, which is often allocated over a much shorter time periods. This comment was received from many researchers.

8.26 To account for the trend away from mixed farms, to separate specialist cropping and livestock units, some studies were focussing on developing a relationship between several specialised farms to provide a larger 'mixed' unit. This expansion of the system boundary involved trading of crop products for manures or store animals to achieve a more balanced whole and may be a more realistic and achievable future model for organic production than every unit being a self contained mixed farm.

Review of published information - production related references

Arable and horticulture - system studies in Scotland

8.27 The first system study in Scotland was started in 1987 at the North of Scotland college of Agriculture at Aberdeen and compared organic and conventional rotations to determine implications for crop yield (Mackay, 1990). Cropping was an eight-course rotation of three years grass and clover, winter wheat, potatoes, spring oats, swedes and undersown spring barley. Manures were imported and applied to the root crops and in later years also to the barley in response to low yield. This was probably because of low a proportion of fertility building crops in the rotation. There were also problems with winter survival of wheat, aphids in swedes and blight in potatoes. Crop yields were between 10 and 50% lower in organic compared with the conventional rotation but with the price premiums at the time, this was considered to be economically viable.

8.28 The next large-scale study to be set up was at Jamesfield Farm, near Perth. This was part of the short-lived Organic Farming Centre founded in 1989 by the Edinburgh University School of Agriculture. Funding was by Safeway plc, Scottish Enterprise and the EU (McKinlay, 1990; McKinlay, 1991). The centre aimed to carry out a programme of research and development, to set-up information and training services and to do market studies. The main output of the Centre was a substantial programme of R&D done at Jamesfield in 1990 and 1991. The trials were annual experiments on specific topics rather than long-term studies within a system. The soil and climate at Jamesfield was ideal for vegetable production. The majority of the research done was on vegetables, mainly brassicas and potatoes. Work included weed control using mulches, pest and disease management and nitrogen rates and sources. There were some spring barley trials, mainly in the second year, looking at overwinter green manures, farmyard manure and the use of biodynamic preparations. There was also some monitoring of organic grassland and beef production. There was some useful output on specific issues, mainly related to vegetables. The emphasis on vegetables probably reflected the retailer's priority area.

8.29 Since 1990, the focus of organic farming research has been at SAC Aberdeen. Two organic units were established at Tulloch (Aberdeen) and Woodside (Elgin) farms, funded by SOAEFD. Research continued on these two sites through the 1990's under the 'Sustainable Farming Systems' banner comparing crop rotations and studying crop production, soil fertility and environmental impact. Rather than compare results with conventional comparisons which is fraught with confounding factors, research was rightly focusing on understanding how organic systems operated, using this knowledge to design improved systems and passing that knowledge on to producers. A wide range of publications has come from this work, from peer reviewed papers to farmers leaflets. Highlights being improved knowledge of nutrient flows and budgeting (Watson et al., 2002) which are central to the functioning of organic systems and, in commercial practice, must be got right before worrying about how to control weeds etc.

8.30 Aberdeen University established the Tesco Centre for Organic Agriculture with funding from the retailer in the late 1990's. Experimental work, funded by Tesco and others, was done on commercial farms and covered a range of issues with an emphasis on vegetables and composting and plant disease control. The emphasis on vegetables was, as for the Jamesfield project, probably a reflection of the priority that retailers put on fresh produce. Most of the staff, and the funding, moved to Newcastle University ( http://www.ncl.ac.uk/tcoa/) in the early 2000's although some of the researchers remained at Aberdeen University and SAC.

8.31 Aberdeen University has a small organic group. A major funder is The Kintail Land Research Foundation. Projects include bracken control, organic dairy cow management, and biological control of pests and diseases. The work is relatively new following re-organisation with the departure of the Tesco Centre to Newcastle, and has mostly not been yet been published. Some of the biological control work is on protected crops (Allan et al., 2003).

Organic crops system studies elsewhere

8.32 In England, Defra has funded long-term system studies on arable crops at ADAS Terrington ( http://www.stocklessorganic.co.uk/) and Nottingham University (Sparkes, 2003) and on field vegetables at HDRA ( http://www.hdra.org.uk/research/ir_econ_veg_systems_network.htm ). Aspects of these will be relevant to Scottish conditions but these studies are stockless, a variant of organic farming at the opposite end of the spectrum to permanent grass livestock-only systems. Stockless systems are being researched in parts of Europe where the introduction of livestock to a predominantly arable area would be difficult and costly. Such a situation does not apply in Scotland with the east coast arable area in a relatively thin coastal strip not far from the stock farms in the uplands. Mixed systems are better in terms of nutrient management and habitat provision and avoid some of the problems of stockless system such as perennial weeds and P & K supply.

8.33 In continental Europe, there are two significant long-term crop rotation studies. At FiBL in Switzerland, the DOC trial has compared conventional, organic and biodynamic systems over three sequences of a 7-crop rotation (Dubois et al., 2000; http://www.fibl.org/english/research/annual-crops/dok/index.php ). All three systems are in the same crop sequence of two years grass/clover followed by potatoes, winter wheat, cabbage or beet, winter wheat and winter barley. The systems differ in fertilisation and plant protection; crop rotation, soil cultivations and crop cultivars have been constant. The study was a split plot design with replication allowing conventional statistical analyses of results. The design allows conventional statistical analysis and has given good information on environmental impact of the fertiliser and pesticide parts of organic conversion (Maeder et al., 2002). However, in commercial practice, crop rotation, crop species, cultivations and cultivars would all differ between systems so conclusions on crop yield and quality need interpretation with care. Yields varied considerably between the systems and years. Potato yields tended to fall with time, this was thought to be due to lower nutrient supply and poorer control of blight.

8.34 In Denmark, a large programme of research is being undertaken by a virtual centre under the ' DARCOF' banner ( http://www.darcof.dk/). A key part of the work is a network of long-term crop rotation studies at four sites, established in 1997. The experiments compare four four-year rotations of grass clover and cereals. Three of the four rotations have over 75% arable cropping, atypical of Scottish organic farms. The aim is to investigate how rotation influences yields, nutrient balances, weeds and diseases and soil fertility on different soil types and with different levels of manure input. In a review of progress, they reported that longer term changes in, e.g. soil fertility are important; soil fertility is influenced by rotation design and manure input; weed communities changes with time and leaching losses of N & K are greater on light soils (Anon, 2002b). These conclusions support the results from UK system studies but in general don't add much new knowledge for the Scottish situation.

8.35 Beyond Europe, the Rodale Institute 'Farming Systems Trial' has been operating in Pennsylvania USA since 1981 and consists of three replicated cropping systems; one organic manure based (maize, soya, wheat, clover/hay rotation), one organic legume based (maize, soya, wheat, green manure rotation) and a conventional system (maize, soya rotation) (Lotter et al., 2003). Through interdisciplinary studies, the project has produced good data on underlying mechanisms but the crops grown, and climate, mean that crop-specific data is not applicable to Scotland.

8.36 To summarise: to research factors such as soil fertility, weed populations and environmental impact that are subtle or change slowly, and need detailed monitoring, long-term studies over several complete crop rotations are necessary. Besides the studies done in Scotland, results from studies in England and at FiBL, DARCOF and Rodale on mechanisms, e.g. soil fertility, are likely of relevance to Scottish conditions and have been included in the reviews included elsewhere in this report. However, actual crop yields and quality will be influenced by the particular design of the experiments and will also reflect the local organic regulations, crop species, crop cultivars, soil type, weeds, pests & diseases, and climate, all of which are likely to be different to Scotland. Therefore, crop-specific studies done outwith Scotland must be assessed on a case by case basis for relevance.

Soil fertility

8.37 As discussed above, maintaining soil fertility in its broadest sense is central to maintaining the productivity and environmental benefits of organic farming (Watson et al., 2002) and has been studied in details in many countries. In the UK, a comprehensive range of studies has been funded by SEERAD and Defra; results were collated in a special supplement to Soil Use and Management in 2002. The eight papers gave an excellent summary of current knowledge on soil fertility in organic systems and how to manage it. Stockdale et al. (2002) reviewed the literature and concluded that there is no evidence that the nutrient cycling processes in soil differ significantly between organic and non-organic farms. However, the relative importance of these processes differs. In organic systems, nutrients are added as insoluble organic sources compared with inorganic fertilisers in non-organic systems. The organically managed soil will have to rely more on chemical and biological processes to make the nutrients available to plants. These processes are dependent on environmental conditions and are likely to be more variable between and within seasons than nutrients added as fertilisers. Stockdale et al. (2002) conclude that there is now plenty of evidence from the literature on best practice, e.g. catch crops, timing of cultivations & manure management, to manage this process but that the challenge is to collate and transfer this information to farmers. Many crop (e.g. nitrogen fixation) and soil biological processes (e.g. mineralisation) are temperature limited and will be less effective in the shorter seasons and cooler conditions of more northern and higher parts of Scotland. This links with the research need identified in the producer and researcher consultations for breeding of cultivars better suited to Scottish conditions.

Weeds

8.38 Weeds are the most common crop protection issue raised by farmers in previous reviews (e.g. Cook, 1997) and in consultations with producers in this project. There has been considerable research done, and in progress on weeds, including SEERAD project SAC/328/02 "Modelling of weed population dynamics" and EU project WECOF at SAC Edinburgh, Defra project OGF0177 "Growth and competition model for organic weed control" at HRI and Defra funded OF0315 participatory research at HDRA. As part of the last project, an extensive review of non-chemical weed control has been written (Bond et al., 2003). This is largely concerned with methodology for the control of annual weeds in row crops. The first three projects listed above are also largely concerned with annual weeds in crops. However, the consultations in this project, and in the OF0315 stakeholders group identified perennial weeds in both crops and grassland as the most difficult to control. In the latter project, docks were seen as the most important weed. The stakeholders, both in OF0315 and this project, believe that much knowledge is available both written and experience, and making it better available would be at least as important as doing new research. Our recommendations for improved information provision in Scotland may help to address this. However, effective options for control of perennial weeds such as docks, creeping thistle and couch grass in crop rotations are limited and there is evidence that they are particularly suited to such systems and becoming an increasing problem (Verschwele & Hause, 2003). Control of perennial weeds is likely to be by a combination of agronomy techniques but, to be fully effective, research to gain a better understanding of their biology, particularly method of spread, in organic systems may be necessary.

Cereals

8.39 Cereals are probably the most commonly grown organic arable crop in Scotland. Research was reviewed by Taylor et al. (2001) and by Cormack (2003). Taylor et al. (2001) concluded that many influences on the performance of the cereal crop are determined by overall system factors, rather than the management of the crop in isolation. The availability of nitrogen and other nutrients will, in particular, be determined by system factors rather then how the cereal crop itself is grown. The general level of weed pressure, and the species encountered, will also be a system factor but the ability of the crop to compete with weeds, functions of its vigour, height and structure, will also be a factor. The evaluation of cultivars for organic systems has been disjointed with separate series of trials funded by HGCA, EFRC and plant breeders (by NIAB) and largely done in England. These efforts were unco-ordinated and were not collated for farmer advice. Only the first of these is still running ( http://www.efrc.com/research/cereals.htm ) and is focused on wide row systems and variety mixtures. Information for Scottish conditions is lacking. There was considerable discussion of pests and diseases by Taylor et al., but, in practice, these are seldom of significance in practice (Cook, 1997). The most consistent crop-specific issues are weed control (discussed above) and poor wheat grain quality, particularly low protein content and poor gluten quality in relation to breadmaking (Taylor et al., 2001). Wheat is the cereal of choice for the main grain buyers for animal feed, but is not well suited to the climate and soil type in much of Scotland. Oats, barley and triticale are better suited to Scottish conditions but are already adequately supplied within the UK (Cormack, 2003). This creates difficulties for prospective new organic arable farmers seeking markets. The characteristics of current wheat cultivars have been selected for against a background of high levels of available nutrients and of comprehensive pesticide applications. This means that they are not best suited to lower nitrogen availability and higher weed pressures of organic systems leading to reduced yields and poor grain quality.

Other crops

8.40 Aside from finding a buyer in an oversupplied market, the main difficulty with organic potato production is control of blight caused by Phytophthora infestans. This is currently controlled by cultural methods or by the application of copper-based fungicide spray. However, the use of copper fungicide is soon to be banned. There are two major research projects being done collaboratively in the UK, funded by Defra and the EU, looking at alternatives. These projects are ongoing and have not yet reported results. However initial indications are that effective replacement of copper-based fungicides will be difficult and continued production of organic potatoes in areas of higher blight risk will become more difficult.

8.41 In addition to the work done at Jamesfield in the early 1990's and more recently at Aberdeen University, the main centre for organic vegetable resarch in the UK is HDRA, with some seed research and cultivar evaluation being done by NIAB. Vegetable variety evaluation has been funded by Defra (project OF0304) and production of advisory handbooks sponsored by commercial companies (Anon 2003d). The data presented is from trials on leeks, cabbage, celery, broccoli, lettuce, cauliflower and carrot. However, all of the sites used to compile the 2003 booklet were in England or Wales so care needs to be taken in interpreting the results for Scotland. Research and practical knowledge of vegetable diseases and their control was collated under Defra project OF0168 (Gladders et al., 1999). As this was mainly based around the biology of the diseases and their control, it should largely be applicable to Scottish growers. Research on pests has not been similarly reviewed.

8.42 Organic fruit production, and research, in the UK is currently very limited. When HDRA reviewed economics for Defra, they based their report on data from only 8 apple, 3 pear and 5 strawberry growers (Anon, 1999). They concluded that for top fruit, the conversion process, which takes 3 years, is an obstacle, as is the high costs of establishing fruit with returns not being generated for some years. Yields may fall by as much as 50% and marketable yield decrease to 50% during conversion. They recommend that establishing a new orchard is technically the most satisfactory way of converting to organic production, however, this is expensive, and due to financial constraints of growers, likely to only lead to a slow increase in the number of organic orchards. Soft fruit is probably of more relevance to Scotland than top fruit. Most conventional soft fruit is produced by specialist growers who would have to diversify into other crops in order to make up a satisfactory organic rotation. This is making them reluctant to convert. They concluded that it was more likely that more organic soft fruit growing could be done by existing and new organic arable and livestock farmers. However, they would lack the technical knowledge. To counter that, a further study by HDRA ( Defra project OF0306) is producing a guide for organic soft fruit producers. This will be compiled partly from UK experience and partly from a booklet produced by FiBL in Switzerland. It will include information on important species, such as raspberries, for which information is currently lacking. The booklet is not yet published but should provide a useful source of information for Scotland. However, it is likely that further research on soft fruit growing systems for Scotland will be necessary.

Livestock

8.43 Virtually all UK-based research into organic livestock production is more or less applicable to Scotland. A significant driver of research, particularly for non-ruminants, has been the introduction of EU regulation 1844/99 governing organic livestock production. This included a number of important, time-limited derogations to accommodate specific technical difficulties which could not be overcome in the short-term. As premium prices for organic produce have been eroded, there is an increasing emphasis on improving efficiency and output quality. A significant body of livestock research is conducted using commercial organic farms, to broaden the base of data collection or to provide resources where dedicated experimental facilities are not available.

Beef and sheep

8.44 An early investigation into organic beef production was conducted in the late 1980's at Jamesfield, comparing organic, low input and conventional systems. In 1991, the organic unit at ADAS Redesdale was established supporting 600 ewes and 40 suckler cows. Since 1995 data has been collected from commercial organic beef and sheep farms linked to the organic unit at Redesdale. Two of these farms are in southern Scotland. Research units have also been converted at ADAS Pwllpeiran, SAC at Tulloch, and at the University of Wales, Aberystwyth. Within the Red Meat Industry Forum ( RMIF) - a technology transfer initiative set up following the outbreak of foot and mouth disease, Newcastle University has been running a series of workshops, farmer training and development work to provide information to organic farmers.

8.45 Direct comparisons of organic and conventional production systems are scarce. Nevertheless, at a systems level there is good long-term data available on overall performance, technical issues and constraints. Generally, few technical difficulties are associated with beef production from the suckler herd (Lowman, 1996; MacNaeidhe & Fingleton, 1997; Shell & Younie, 2001). In terms of overall performance levels, strong parallels can be drawn with clover-based, or extensive conventional production systems. Younie & Mackie (1996) quoted a gross margin per head for organic 18 month beef 30% above that of a heavily fertilised conventional system. Gross margin per hectare was similar for both systems given the lower stock carrying capacity of the organically managed sward. Although problems exist on specific farms e.g. trace element deficiencies, overall health status is generally good. In both beef and dairy cattle systems internal parasites appear to be more easily controlled than in organic sheep flocks (Keatinge et al., 2004).

8.46 The impact of conversion on organic sheep production depends very much on the intensity of the production system (Keatinge, 2001). Less impact can be expected in extensively managed sheep flocks, compared to lowland flocks managed at higher stocking rates. At ADAS Redesdale, a direct comparison of physical and financial performance has been made of organic and conventional hill sheep systems, using pure-bred Scottish Blackface ewes. Although animal performance levels were significantly lower at similar stocking rates, improved prices for organic lamb were sufficient to ensure that flock gross margin was similar to or above that of the conventional system. Comparable levels of gross margin have also been reported from lowland organic and conventional flocks in Southern Ireland ( TEAGASC, 1997). Many organic sheep farmers use other agri-environmental schemes, in addition to the Organic Farming Scheme, to maintain economic viability at lower stocking rates (Elliott & Keatinge, 2001). Controlling internal parasites can be a significant problem in organic flocks, particularly specialist systems with little diversity of cropping or livestock enterprises at the start of conversion (Keatinge et al., 2004). While circumstances are always likely to remain challenging for the organic sheep farmer, significant reductions in anthelmintic use can be brought about through management, nutritional and genetic routes (Keatinge et al., 2004).

8.47 Although the ending of the derogation for non-organic feeds will have a significant impact on organic beef and sheep production, the effect is likely to be less than in organic pig and poultry production. Comparative data is available on the finishing performance of lambs on high-clover silage (Keatinge & Murray, 1994), and using alternative proteins such as beans (Murray & Keatinge, 1994). Organically produced straights are now available at reasonable cost, and are relatively easy to use in lowland situations. However, the availability of 100% organically produced feed, in a form suitable for feeding under extensive conditions (blocks or cobs) is likely to be a significant problem which may impact on the continuing organic status of hill flocks.

Organic dairy production

8.48 Defra have supported a dairy research herd at IGER Trawsgoed since conversion began in 1991. This project also involves data collection on commercial organic herds, mainly located in Wales and South West England. A dairy herd is undergoing conversion at the University of Newcastle, Nafferton Farm, which will provide a direct comparison with a conventionally managed herd on the same site.

8.49 Research at IGER provides good information on physical and financial performance, input:output relationships and technical constraints (Newman & Weller, 2001). Latterly, research is directed towards comparing the efficiency and performance of two contrasting systems of milk production - one pursuing mainly economic objectives and the other a more self-contained closed system. This includes objectives to assess the nutritional value of farm-produced crops, improve feed efficiency, persistency of milk yield and milk quality. Production and animal health parameters were recorded for a sample of UK organic herds by Hovi et al. (2001). Weller & Bowling (2000) reported mastitis incidence, lameness, metabolic disorders and treatments on 10 commercial organic farms. Difficulties associated with forage energy and protein supply (Weller & Cooper, 2001), are currently being addressed in a collaborative desk-study currently led by ADAS ( OF0328). Within this study a database model has been developed modelling the effect of varying cropping systems on whole-farm self-sufficiency. A recent project at SAC Edinburgh, part funded by the Milk Development Council, modelled the physical and financial implications of varying cow breed type used in organic milk production.

8.50 The main regional differences in organic dairying systems are likely to be related to soil and climatic influences on potential self-sufficiency in organically grown energy and protein crops, the seasonality of production, and overall market conditions (Franks, 2003) for organic milk and processed products. While much of the current information can be extrapolated to Scotland, it is likely that more locally derived sources of data, particularly on forages, would be useful for organic dairy farmers.

Pig production

8.51 There is no dedicated organic pig research facility in the UK. One major Defra-funded research project ( OFO169), lead by ADAS with collaboration with Newcastle University, Pig Improvement Company and TESCO, has been conducted on commercial organic pig farms. This ended in 2003. At present, there is little or no organic pig research in the UK.

8.52 Project OFO169, was a wide-ranging study designed to address the main issues associated with organic pig production. Measurements were made of physical and financial performance on commercial farms. Supporting information was compiled from literature review and distilled into a technical guide covering management, nutrition, economics and best practice. A number of specific experiments were undertaken comparing the effect of breed type (traditional - Saddleback and Saddleback x Duroc, with a modern commercial hybrid - Camborough 12) on maternal characteristics and performance of the progeny. In addition, the interactive effects of breed type, feed type and housing on finishing performance, carcass and eating quality were also assessed. Limited data was collected on animal health and parasite burden. Ranging behaviour was studied to determine effects on sward utilisation (Mowat et al., 2001), animal welfare (Kelly et al., 2002), and manure deposition (Marcellis et al., 2002). However, a full environmental assessment of the impact of including an organic pig enterprise within the rotation was beyond the scope of the project. The study provides valuable 'benchmark' data for organic production in the UK. However, the financial sensitivity of the production system to small changes in pigmeat or feed input prices was emphasised (Martins, 2001).

8.53 It is likely that the findings of the research are highly relevant to Scottish conditions. Slight regional variations may occur in the type of crop rotations practised, and market conditions for organic pigmeat. Information is still lacking on some technical aspects e.g. most appropriate genotypes, nutrition (the role of forage in the diet, amino acid nutrition of the young pig), ecto and endo parasite control and overall environmental impact within the rotation. Furthermore, there has been to research to evaluate the role of more novel production systems e.g. the integration of pigs and grazing cattle (Sehested et al., 1999).

Poultry production

8.54 There is no dedicated organic poultry research facility in the UK. Over the last 5 years, a significant amount of research, mainly technical workshops, simulations and literature reviews has been conducted into organic and traditional poultry systems at ADAS Gleadthorpe. The main conclusions from this work are given below. Some development work on the integration of poultry and agro-forestry systems is beginning at Sheepdrove Farm in Berkshire, with private funding through the Sheepdrove Trust.

8.55 Research into organic poultry has been funded almost exclusively by Defra, and is directed towards specific technical issues related to implementation of EU reg. 1844/99. These issues are more acute in the poultry sector given the contrast between conventional poultry systems, and organic production, which emphasises reduced stocking density, lower inputs, less environmental control, and a greater link between production system and the land used for crop production and manure disposal. The application of stricter organic standards in the UK, particularly those certified by the Soil Association, are often seen as reducing the competitiveness of UK organic producers relative to those in other EU countries. A defra-funded study tour by ADAS (Elson, 2001) identified significant differences in the way organic poultry regulations (and potential for specific derogations) were being interpreted in France at the time, compared with UK certifying bodies.

8.56 At ADAS Gleadthorpe, investigations have been made into the effect of breed suitability, and aspects of management and system design, comparing traditional UK breeds with a modern hybrid, under an extensive production system (Gordon, 2002). Parameters measured in this wide ranging study included growth patterns, effect of high and moderate nutrient rich diets, meat yield and quality, brooding performance, range behaviour and bird health and welfare. The work characterised the relative merits of varying breed, management and rearing options for extrapolation to a range of extensive poultry systems.

8.57 Over the last 50 years most poultry in the UK have been managed in specialist indoor systems. This has meant a lack of information on methods of integrating poultry into crop rotations, which take into account the nutritional and physiological needs of the birds, as well as the recycling of nutrients between soil, plants and bird. The integration of poultry into whole system rotations was addressed in a desk study by Gordon (2001). This focused particularly on the supply of home-grown protein, nutrient recycling and gross margins from different crop rotations. The impact of total protein supply from organic sources, on amino acid nutrition, manure composition and overall efficiency was highlighted.

8.58 Technical difficulties associated with organic pullet rearing were addressed in a further desk study by Gordon (2000). This focussed on the effects of photoperiodism on bird maturity and performance, feeding (particularly amino acid nutrition, and potential links with injurious feather pecking), housing and pasture management, and food safety. A similar study addressed technical issues in the organic breeding and hatching sector (Gordon, 2003). An ongoing project ( OFO327), also based at ADAS Gleadthorpe, is using simulation modelling to compare nutrient inputs and outputs to assess the feasibility and performance implications of meeting the feed requirements of the laying hen solely through organically produced ingredients. One aspect of the study is to evaluate the amino acid composition of organic and non-organic wheat and peas grown at various locations throughout the UK.

8.59 The research conducted to date in England has identified most of the technical issues associated with organic poultry production in the UK as a whole. Some of these difficulties could be expected to be exacerbated under Scottish conditions where wetter weather and shorter days may affect photoperiodism, ranging behaviour, poultry house management, and the range (particularly of protein) crops which can be produced. Desk studies and simulation exercises provide a useful framework for understanding the likely extent of problems and potential solutions. However, further research is required to validate the conclusions of this work, particularly in terms of amino acid nutrition, bird health and welfare, endo-parasite control and the contribution of pasture to overall management and nutrition. These information deficits are not restricted to Scotland, and therefore any proposals for research funding would have to be weighed up against the cost benefit for the Scottish organic poultry sector.

Animal health and welfare

8.60 High regard for animal welfare is a central tenet of organic farming, and is a significant purchasing trigger some consumers (Harper & Henson, 1998). Overall, there are disease issues which cause concern on organic farms, which are usually species specific. However, there is also a wider debate on the suitability, behaviourally and physiologically, of modern breeds (particularly of monogastric animals) for organic management conditions. As yet only a few studies have addressed this aspect, which is likely to require long-term study and system development. Relatively little research has been done in the UK comparing the incidence of zoonotic diseases in organic and conventional livestock, although there is some Danish evidence for higher levels of Campylobacter in organic poultry (Heuer et al., 2001).

8.61 Various surveys have been undertaken to determine the nature and extent of disease problems in organically managed livestock (Kintail, 1991;Roderick & Hovi, 1999). The results are consistent, and identify a number of specific issues which tend to cause concern to the organic farmer - internal parasites in grazing stock, nutritionally related reproductive problems in breeding stock, mastitis in dairy cows, clostridial vaccination, flystrike in sheep etc. Some of these are already being addressed in UK research programmes, for example, work on parasite monitoring in organic sheep is being conducted by SAC at Tulloch and on a number of commercial organic farms. Researchers at SAC Edinburgh have been investigating the nutritional basis of immunity to roundworms in sheep (Houdijk et al., 2001) and the potential role of bioactive forages (Tzamaloukas et al., 2004) for parasite control, applicable to both organic and conventional production systems.

8.62 Very few studies have been done on alternative therapies such as homeopathy and herbal treatment, underlining the lack of factual data on the safety and efficacy of these approaches. Some observation studies have been undertaken (Lowman, 1989; Keatinge, 1996). The first major study on the use of homeopathy in the UK, for mastitis control in dairy herds, is currently being carried out by Bristol University Vet School and Reading University.

8.63 European and now UK research is being directed towards methods of measuring animal health and welfare, particularly in relation to the implementation and interpretation of the organic standards. The advantages of being able to quantify health and welfare are seen in terms of benchmarking current performance as a baseline for improvement, or for comparing organic with other farming systems. Scoring systems have been developed on the continent, notably for cattle (Bartussek, 1999). However, these have tended to be input based i.e. on criteria such housing design, lying area available etc. Increasingly the greater value of output parameters e.g. incidences of lameness, mastitis, flight reflexes etc are recognised as a more valid measure of an animals physical and psychological well being (Main et al., 2003).

8.64 Existing knowledge and information on animal health, welfare and husbandry was drawn together by Hovi & Kossaibati (2002a) to provide a resource of advisory material on organic livestock. The compendia produced cover pigs and poultry, sheep/goat, dairy and beef systems. Targeting advisors, inspectors and vets, Hovi & Kossaibati (2002) used a questionnaire survey to assess perceptions of the impact of organic livestock standards on animal welfare. Efforts have been made to develop herd/flock health plans (Huxley et al., 2003; Hovi, 2003), as a more meaningful tool to improve the planning and management of animal health on organic farms. A decision support tool based on disease risk assessment was developed with Defra funding ( OF0310), to address the controversial issue of vaccine use on organic livestock farms in the UK.

8.65 At a European level, a comprehensive resource on animal health and welfare was developed under EU funded Network on Animal Health and Welfare in Organic Agriculture ( NAHWOA) which ran for three years until 2002. The network included 15 research institutes from eleven EU countries, including representatives from England, Scotland and Wales. The main aim was to provide a joint platform for research organisations involved in organic livestock production and to create a forum for an on-going discussion on animal production, welfare and standards in organic farming. Information and research results from a series five workshops were collated into a single volume ( CABI, 2003). Although much of the contents relate to European livestock systems, it is the most up to date and comprehensive work on the subject, and includes many papers which can directly or indirectly be related to UK conditions. Scottish researchers are currently involved in an another wider network financed by the EU from 2003 onwards - Sustaining Animal Health and Food Safety in Organic Farming ( SAFO). This should continue to be a useful vehicle to incorporate and interpret developments in organic livestock production across Europe to the Scottish situation, and reduce the research need in areas of common interest.

Organic grassland and forage production

8.66 Organic farmers have tended to take a lead in the use of forages, herbs and generally more diverse seeds mixtures (Weller & Jones, 2002), compared to conventional producers, who historically have tended to rely on bagged fertiliser. Over the last 30 years, extensive research and development has been carried out into production from grass and legumes (notably white clover) under conventional farming systems, covering both upland and lowland situations (Davies & Hopkins, 1996). Much of this research can, or has already, been applied in organic production.

8.67 In the pursuit of more home grown protein, an increasing range of crops e.g. peas, beans, sainfoin, lucerne, lupins, birdsfoot trefoil etc are also being evaluated at IGER, mainly for application in lower input conventional systems. Some of this work has potential for Scotland, however without careful choice of species and variety, novel crops such as Lotus, or even more sensitive native crops such as peas, are less likely to be suited to Scottish conditions.

8.68 At present, there is a derogation for the use of a limited proportion of non-organically produced seed on organic farms. Organic seed, even for relatively common species is in short supply. Furthermore, there is a dearth of information on the agronomic requirements and production potential of seed produced specifically for use in organic systems (Marshall & Humphries, 2002). If breeding initiatives for organic seed are focussed on the requirements of the South and West of the UK there is danger that Scottish producers may lose out, in terms of varieties and cultivars suited to the climate and growth pattern required for production in Scotland.

8.69 Annual weeds are generally not considered a problem in organic grassland, and do not tend to persist beyond the establishment phase of an organic ley. With regard to perennial weeds, specific research has been carried out at IGER investigating cultural control of docks in organic grassland. Although some progress was made in identifying management strategies (e.g. soil aeration, use of competitive seeds mixtures) which affect the establishment and spread of docks, no single method was identified to adequately control dock infestation, and they remain a significant problem on some organic farms. Anecdotal evidence suggests that on upland organic farms, rushes are an increasing problem. No research has been carried out on cultural control of rushes in recent years.

8.70 Herbs such as chicory, plantain are often included in organic grassland mixtures to improve drought resistance and enhance mineral nutrition of grazing livestock. Chicory appears to establish well under Scottish conditions (Younie et al., 2001), and significant improvements in lamb trace element status have been recorded in grazing lambs. There is increasing interest in the antiparasitic effects of Lotus, and particularly chicory (Marley et al., 2003). Collaborative trials with ADAS are being conducted at SAC Aberdeen ( OFO185) evaluating the effect of chicory on parasite burden in lambs. EU funded work is ongoing at SAC Edinburgh, in a programme to screen a range of native and novel plant species for direct and indirect effects against internal parasites (Athanasiadou, 2002). Much of this research is developmental, and further research is required to fully understand underlying mechanisms, and develop approaches for practical application.

Environmental Impact

8.71 A recent comprehensive review was completed for Defra in 2003 (Shepherd et al.), with authors drawn from ADAS, Elm Farm Research Centre, IGER and Defra. A refereed paper based on this review has been submitted for publication to The Journal of the Science of Food and Agriculture. The review included the results of previous reviews by authors in Denmark (Hansen et al., 2001), New Zealand (Condron et al., 2000), the EU (Stolze et al, 1999) and the UK (Stockdale et al., 2001), as well as original publications. Shepherd et al. concluded that, for a number of reasons, comparing organic and non-organic systems is not straightforward:

• basis of comparison: Arable and horticultural crop yields from organic systems tend to be less than in conventional systems. Organic yields have been reported to be, on average, 50-95% of the conventional yield, depending on species and position in the organic rotation (Watson et al., 2002). Therefore, one issue is how to take account of the lower yield potential of organic systems when assessing environmental impact. Assessment of relative environmental impact may be skewed depending on whether it is measured per unit of land area, per unit of economic activity or per unit of produce.
• type of farms compared: Most trials have compared lowland mixed crop and livestock organic farms with similarly structured conventional farms. Therefore, this would not include comparisons of organic farming systems with the most intensive conventional farms, which is perhaps a comparison that should be made. There are also few comparisons between organic and conventional extensive farms (i.e. upland grass based livestock systems).
• lack of clear definition of what is meant by 'conventional' agriculture. Whereas organic agriculture is defined in EU and Sector Body standards, there is no similar definition for what is meant by conventional agriculture, and practices in both systems will change over time, especially in relation to market signals.

8.72 As Shepherd et al. concluded, the vast majority of environmental impact studies relate to lowland systems and there is a dearth of information from upland livestock systems that form the vast majority of the organically farmed land in Scotland. The available data has been summarised by the Organic Centre Wales ( OCW) in a review funded by the Countryside Council for Wales and the Welsh Assembly Government. At the time of writing this is not complete, but we are grateful to the OCW for allowing us access to the third draft of the report.

8.73 While standards for organic farming do exist, in practice, they are not wholly implemented on every organic farm:

• they can be subject to derogations e.g. use of some non-organic inputs by derogation as restricted practices.
• some expected changes are not mandatory, for instance organic conversion need not necessarily lead to lower stocking rates of sheep or the introduction of cattle onto hill farms, both recognised as probably beneficial to biodiversity.
• attention to non-cropped areas, e.g. hedges and woodland as wildlife habitat is encouraged, but the extent of any activity will depend primarily on the enthusiasm of individual farmers. This applies equally to non-organic and organic farmers.

8.74 Therefore, great care has to be taken in drawing conclusions when comparing farming systems, particularly in desk studies where assumptions are made about the implementation of the organic standards.

8.75 We have reviewed the literature under the two main organic farming types in Scotland: hill & upland, and mixed ley & arable farms.

Hill and upland

8.76 The vast majority of organic land in Scotland is unimproved semi-natural grassland, primarily grazed by sheep. The main management changes on conversion to organic methods are likely to be:

• Reduced stocking rate of sheep (not mandatory but a likely outcome of the reduced home-grown fodder production with the elimination of nitrogen fertiliser)
• Introduction or increased in cattle (recommended but not universal)
• Elimination of synthetic fertiliser inputs (affecting only inbye and improved land)
• Elimination of herbicides (likely to affect a limited area, mainly for bracken control)
• Reduction in the use of anthelmintics (derogations are available to continue use of certain products in some cases)
• Changes in dipping (organo-phosphates not allowed, pyrethroids are allowed).

8.77 All of these changed practices will have environmental impacts, some positive and some negative. However, as the OCW study for CCW reports (Anon., 2004b), some of these changed practices are optional, some will affect only limited parts of the farm system, and some may be subject to derogations to allow continuation of non-organic practices. Data to confirm what actually happens, in practice, on organic hill farms, and on how this differs from pre-conversion farming practice, are not available. Therefore, it is difficult to quantify the likely actual environmental impacts of these farms. Any projection will have to make assumptions about actual practices. Assuming that the organic standards, mandatory and optional, are applied in full, on all farms, will give an incorrect picture.

8.78 Reviewers are agreed that the impact of organic conversion on unimproved semi-natural grassland is likely to be substantially less than on lowland arable, horticulture of mixed farms. This is not from comparative measurements, but from the observation that following conversion of most lowland systems, the elimination of herbicides, pesticides and synthetic fertilisers, and the introduction of more varied cropping are all likely to lead to marked improvements in biodiversity and water polluting potential within a relatively short timescale.

Impact on Biodiversity

8.79 There is a general agreement, based on research in non-organic systems, that stocking rate has an impact on vegetation composition (Shepherd et al.; Anon., 2004). Long-term intensive grazing will tend to encourage grass domination, and low grazing pressure encourages heather and scrub vegetation. Which is preferable will depend on the objectives for that particular farm and area. The only UK measured data is from the Defra study at ADAS Redesdale in Northumberland (Adamson et al., 2002). A number of hefts, both organically and non-organically managed were compared. They concluded that stocking rate was the main factor affecting vegetation composition, irrespective of management system. Higher stocking rates resulted in a decrease in Calluna vulgaris and an increasing dominance by rough grasses. There may be subsequent effects on birds if habitat change was significant but this would only be likely with more extreme changes in stocking rate.

8.80 The introduction of cattle is seen as beneficial in encouraging more flexible grazing management and more diverse vegetation. Although encouraged by certification bodies, in practice increase in cattle numbers is probably limited due to the costs of buildings and additional management input needed (Anon., 2004b). After the MTR, the introduction of cattle may become even more difficult given the current level of dependence of cattle gross margins on headage support payments.

8.81 Prophylactic use of anthelmintics for internal parasite control is not allowed, but their use may be permitted to treat animals under certain circumstances. Some products, notably the avermectins (used also for sheep scab), are thought to have potential residual effects in the faeces which may affect invertebrates feeding on the dung for several weeks following excretion. Concern about widespread permissions for the use of anthelmintics was expressed in the consultation with Jamie Robertson of Aberdeen University. Studies from Ireland reported by Anon. (2004) suggest a link between reduced anthelmintic use and dung beetle numbers. To better understand the situation, the actual use of anthelmintics on organic farms needs to be measured, and the effects of drug residues on invertebrates and animals further up the food chain needs investigating.

Impact on air quality

8.82 The impact of organic conversion on gaseous emissions is complex and data from organic systems is very limited. Reduced stocking rates are likely to lead to lower emissions per unit area of ammonia, and methane (Shepherd et al., 2003). However, methods of housing and manure handling will influence ammonia losses and a higher fibre diet, as is likely following organic conversion, may lead to increased methane losses per animal. Nitrous oxide is lost from soils and manures in appropriate conditions; it is unlikely that there would be a significant effect of organic conversion. Net emissions of carbon dioxide will depend largely on fossil fuel use. The main impact of organic conversion will be on reduced use of fossil fuel for the production of fertilisers. However, this benefit will be largely realised at the point of fertiliser manufacture rather than on the farm.

Impact on water quality

8.83 Risks to water quality are primarily from nutrient and manure leaching and run-off, and from the disposal of sheep dip.

8.84 The organic standards ban organo-phosphorus and organo-chlorine (gamma HCH) compound dips, mainly because of human health concerns. Synthetic pythrethroids are permitted with restrictions, but are more toxic to aquatic organisms than organo phosphates (Anon., 2004b). Therefore, the main risk to the environment is probably to aquatic life and drinking water quality associated with the disposal of spent dip. It is common practice to spread spent dip on land either directly or after treatment with certain chemicals or mixing it with slurry. Therefore the impact of conversion to organic methods will depend on what change in product use is realised, and on how carefully the spent dip is disposed of. Data of actual practice would need to be collected to determine whether organic conversion has a negative or positive impact.

8.85 The main nutrient pollution risk will be from the storage, handling and application of manures and slurries. The quantities involved following conversion may increase if cattle numbers are increased but in many cases will be unchanged. For all agricultural systems, the Code of Good Practice for the Prevention of Environmental Pollution from Agricultural Activity provides advice on the storage and use of slurries manures and composts. There are no additional standards prescribed for organic procedures at the present time. Storage and handling methods are not likely to show a significant difference between conventional and organic farming (Frost, 2003) so the risk of pollution will depend on how closely the code is followed on individual farms irrespective of organic or conventional. Synthetic fertilisers are likely to be used on only a small proportion of the land area on most hill farms and therefore would be unlikely to lead to significant environmental impact when discontinued following organic conversion.

8.86 The use of other pesticides such as herbicides and fungicides is generally very small on conventional hill farms so the benefit of conversion is likely to be limited.

Impact on soil quality

8.87 Soil fertility is determined by a set of interactions between the physical and chemical environments of the system and by biological activity. Organic matter is linked intrinsically to soil fertility, because it is important in maintaining good soil physical conditions (e.g. soil structure, aeration and water holding capacity), which contribute to soil fertility, and it is an important nutrient reserve. Stolze et al. (1999), in their review of the environmental effects of organic farming, concur with the view that soil organic matter, biological activity and soil structure are all important aspects of soil quality, but also include susceptibility to soil erosion. Although there is no specific data comparing conventional and organic farms, it can probably be assumed that grazing pressure and therefore erosion rates on unimproved grassland should be lower on organic hill farms (Anon., 2004b). It is unlikely that this would result in any significant change in soil organic matter content or structure. Reduced use of use of anthelmintics may have an effect on soil biological activity but research is lacking. Therefore, overall, impact on soil quality under unimproved grassland is likely to be minimal following organic conversion. There will also be effects of organic management on soil quality of improved and in-bye grassland on hill farms. However, these occupy a much smaller land area and the impact in practice will depend very much on how the grass and grazing pressure is managed, rather than the change to organic methods per se so it is not possible to generalise.

Mixed farms (or ley-arable farms)

8.88 The key difference in conversion to organic methods compared with hill and upland farms are changes in the crops grown and in the ways that they are grown. There is plenty of evidence that environmental benefit is likely from the cropping part of the rotation. Different crops and a better mix of spring and autumn sown crops are likely to be grown. This wider variety provides greater structural diversity, habitat diversity and, therefore, should lead to a greater diversity of wild flora and fauna (Unwin et al., 1995).

Effects on biodiversity

8.89 Stolze et al. (1999) undertook a thorough review of the effects of organic farming on the ecosystem and concluded that organic farming clearly performed better than conventional farming in respect of floral and faunal diversity, and that organic farming had greater potential to deliver wildlife conservation and landscape effects. Shepherd et al. (2003) collated the conclusions of several reviews addressing the impact of organic farming on biodiversity of the whole system under UK conditions (Unwin et al., 1995; Younie & Baars, 1997; Gardner & Brown, 1998). There was conclusive evidence from a number of countries that organic mixed farming systems favour greater diversity of plants, invertebrates and birds. A more recent report of work on paired organic and conventional mixed farms in southern England and in Wales showed significantly higher total bat activity on organic farms (Wickramasinghe et al., 2003).

8.90 In contrast to most hill farms, a significant feature of organic lowland farms are field boundaries and other non-cropped areas. These contribute to habitat diversity and may generally be better managed on organic farms because of the likely greater interest of these farmers in conservation. Gardner & Brown (1998) concluded that the nature and extent of these habitats are the key to determining the overall biodiversity of the agricultural areas, because it is these non-cropped areas that are the reservoirs for faunal and floral diversity. Wickramasinghe et al. (2003) concluded that higher bat activity on organic farms may reflect features such as taller hadgerows and better water quality on the farms that they studied.

8.91 Some aspects of organic crop production can have a negative impact. Mechanical weed control can have a negative impact on ground nesting birds (Fuller, 1997), but this will depend on the timing and method of control (Welsh et al., 2002). The use of wider row spacing, which is required for inter-row hoeing in cereals, may in itself encourage ground nesting birds into the crop (Welsh et al., 2002).

Impact on air quality

8.92 As noted above, the impact of organic conversion on gaseous emissions is complex and data from organic systems is very limited. Most of the gaseous emissions relate to livestock and manure. Shepherd et al. (2003) concluded that it seems likely on balance that there is little difference between organic and conventional systems in the amount of ammonia which is lost from the system per unit of yield, but it is likely that emissions are lower per unit area. The main risk of Nitrous oxide emissions arise from manure and from the waterlogging of soils by heavy rainfall following fertiliser application. In the absence of direct measurement Shepherd et al. (2003) concluded that it is not possible to assess whether there is any difference in risk from organic or conventional production. About 75% of methane on farms is emitted directly from ruminant animals (chiefly cattle and sheep). There will tend to be higher emissions from organic systems, as organic diets tend to be high in roughage and low in concentrates. On average, production intensity is lower in organic than conventional systems, so methane generation from organic sheep and cattle farms is likely to be greater per unit of food produced. Because of the lower stocking densities, it maybe similar or less on an area basis. Net emissions of carbon dioxide will depend largely on fossil fuel use. The main impact of organic conversion will be on reduced use of fossil fuel for the production of fertilisers. However, this benefit will be largely realised at the point of fertiliser manufacture rather than on the farm.

Impact on water quality

8.93 Risks to water quality are primarily from nutrient and manure leaching and run-off, and from pesticides.

8.94 Organic mixed farms operate at a lower level of nitrogen intensity than conventional systems, with nitrogen inputs from fixation by legumes, or from importation of animal feed onto the farm rather than from the use synthetic nitrogen fertilisers. Also, organic farming adopts many of the practices that should decrease losses: maximising periods of green cover, use of straw-based manure, lower stocking densities. Shepherd et al. (2003) concluded that the body of evidence suggests that leaching losses are generally less from organic systems - though this is not always guaranteed. For instance, there is a particular risk of high leaching losses following ploughing of legume rich leys when nitrogen mineralisation is in excess of crop demand, especially if autumn sown crops are grown in this situation (Philipps et al., 1995). There is no direct evidence of differences in phosphorus losses between organic and conventional agriculture.

8.95 Pesticide use in organic farming is very restricted. A small number of pesticides are approved for organic use (principally copper, sulphur, natural pyrethroids, and derris), and they are only used as a last resort in limited situations. Organic farmers use no herbicides, some of which (such as isoproturon) have presented particular water pollution problems. Pesticide pollution of water in organic farming will therefore be far less likely than in non-organic agriculture.

Impact on soil quality

8.96 As discussed above, organic matter is linked intrinsically to soil fertility, because it is important in maintaining good soil physical conditions (e.g. soil structure, aeration and water holding capacity), which contribute to soil fertility, and it is an important nutrient reserve. Shepherd et al. (2003) reviewed several studies that showed higher levels of SOM on organic farms, explained by higher inputs of manures. However, the rate of change will be slow as the additions are only a small proportion of a large existing pool of organic matter in the soil. The long-term DOC experiment in Switzerland after 10 years showed soil C levels of 0.79% in non-organic compared with 0.92% in organic (Raupp, 1995). It seems reasonable to assume that mixed organic farms will mostly have improved soil organic matter content and hence soil fertility under its many measures such as soil structure, nutrient content and resistance to erosion.

9.87 Shepherd et al. (2003) concluded that earthworms are generally more numerous on organic farms but that studies of microbial activity have been less conclusive. They also believed that the lower levels of available nutrients, reduced use of veterinary medicines and the absence of most other pesticides should also be of benefit to soil quality but definitive studies have not been done.

Other farm types

8.98 The main farm type in Scotland not included above is the grass-based lowland livestock farm, e.g. dairy or beef. Many of these will have at least some cereals and rotate part of the grass leys with crops, so the benefits for mixed farming discussed above will apply. However, all-grass farms will not have the habitat diversity benefits of mixed farms. The diversity within the grass fields will depend on the starting point, i.e. the species mixture at start of conversion, and on how intensively that is managed in terms of stocking density and applications of manure. Organic management per se will not necessarily result in a change. Atkinson et al. (1996) reported little change in a ryegrass and white clover sward apart from a higher proportion of clover which was probably the result of the absence of mineral nitrogen applications post conversion. A survey of mainly-grass cattle farms in Ireland showed a greater biomass, diversity and species richness of dung beetles on organic compared with comparable conventional farms (Hutton & Giller, 2003).

Externalities

8.99 The financial cost of the negative environmental impacts of conventional agriculture were estimated by Pretty et al. (2000) to be over £2,000m per year for the UK. Most of these costs, for example to remove pesticides from water, are not included in the retail cost of food. Pretty et al. suggest that these external costs could be brought within the price of products to help encourage systems of farming less harmful to the environment. Whilst it is probably unrealistic to expect this to occur in the near future, their analysis, interpreted for Scottish conditions, may be a useful method for quantifying the relative environmental benefits of farming systems in Scotland and help direct policy decisions.

Quantification of environmental benefit

8.100 A generalised quantification of environmental impact of organic farming systems in Scotland is not possible. This is because it will depend, as discussed at the start of this chapter, on: 1) what intensity of conventional system you compare the organic system with, 2) how organic standards and derogations are applied in practice, 3) how non-cropped land is managed, and 4) the ethos of the organic producer, i.e. whether maximising output and profit, or maximising environmental benefit.

Farming systems beneficial or detrimental to the environment in Scotland

8.101 Definitive categorical statements are not possible as the outcome in terms of environmental impact will depend on: 1) what intensity of conventional system you compare the organic system with, 2) how organic standards and derogations are applied in practice, 3) how non-cropped land is managed, and 4) the ethos of the organic producer, i.e. whether maximising output and profit, or maximising environmental benefit. A lack of UK, and particularly Scottish, field research data on environmental impact of organic conversion from hill and upland systems are also limiting.

8.102 The conversion to organic methods of mixed arable and livestock farms will, on average, result in improvements in biodiversity, soil and water quality. However, on some farms and situations, some impacts of organic farming may be negative, for instance greater nitrate leaching loss to ground water after ploughing-in clover, destruction of nests of ground nesting birds when hoeing for weeds, and greater gaseous emissions from livestock and manure.

8.103 Conversion of grass-based lowland farms will realise less environmental benefit compared with mixed farms, because the diversity of habitat will be less and the pre-conversion levels of pesticide use will be less than on farms with crops.

8.104 Conversion of unimproved grassland is unlikely to yield significant environmental benefit, as the changes to land and stock management following conversion are likely to be minimal. However, direct field measurements are lacking, and none that we could find have been made in Scotland.

8.105 Conversion to specialist organic horticulture may realise environmental benefit but it would depend on what the previous land use pattern was. There may be adverse effects on the environment from; for example, an increased use of plastic mulches, or a greater energy use if flame weeding is employed.

Food Quality

8.106 Two of the main reasons promoted by organic organisations for the consumption of organically grown food, are health and nutritional benefits. A Soil Association review (Heaton, 2001) concluded that collectively, organic food was superior to non-organic but it also showed that many studies resulted in inconclusive or no differences. They reported no substantial studies of health effects on humans. This lack of conclusive proof for claims of nutritional, taste and health benefit has led the Advertising Standards Authority to ban promotional material making such claims. There is a fundamental contradiction here in that one of the primary reasons for purchase of organic food is health benefit which is unsubstantiated and can not be used on packaging or point of sale material.

8.107 Responsibility for food quality and safety in the UK rests with the Food Standards Agency ( FSA). The Agency's position on organic food was stated in their response to a Welsh Assembly consultation (Anon., 2002). "The most important and over-riding point is that the nutrient balance of the diet as a whole is what matters, and differences in nutrient composition of different foods are relatively unimportant. A varied and balanced diet which includes plenty of fruit, vegetables and starchy foods should provide all of the nutrients that a healthy individual requires, regardless of whether the individual components are produced by organic or conventional methods. Consequently any differences in the nutrient content of organic and conventional foods are relatively unimportant. However, it has been suggested that organic food is nutritionally superior to that produced conventionally. The Agency view is that this assertion is not supported by the available evidence."

8.108 Following substantial pressure form the organic movement, the Agency held a research workshop in November 2002 (Anon., 2003). Its objective in doing so was to encourage debate and help the Agency to decide whether it should fund any research in this area in order to help inform consumer choice.

Nutrient content

8.109 Presentations at the FSA 2002 workshop showed that nutrient content of fruit and vegetables varies considerably, depending on variety, growing conditions, farming practices, post-harvest distribution and storage conditions and processing and preparation methods. Reviewing 99 studies, Heaton (2001) discarded 70 for various reasons including insufficient control of these confounding factors. Of the 29 studies remaining, 22 compared dry matter, vitamin or mineral contents of fruit and vegetables. Of the 22 vegetable studies, 13 were peer reviewed. On a fresh weight basis, 7 showed higher mineral content in organic crops, 6 showed inconsistent or no difference and only 1 showed higher content in non-organic crops. Studies on vitamin C showed a similar pattern. However, several of the studies also showed a higher dry matter content in organically grown produce so the higher mineral and vitamin contents could simply be due to less dilution by a lower water content compared to non-organic. Heaton (2001) concluded that although the reviewed data could be interpreted in different ways, there was sufficient trend towards higher mineral and vitamin contents in organically grown fruit vegetables to justify further research.

8.110 Speakers at the FSA workshop noted that, in addition, the bioavailability of nutrients can be significantly influenced by preparation and processing. The same is likely to be the case for secondary metabolites, although far fewer data are available. They noted that, although there is clear evidence that increasing consumption of fruit and vegetables would have significant public health benefits, the evidence linking such benefits to levels of specific nutrients or secondary metabolites was not currently available.

8.111 Professor Sue Southon, IFR, argued that information about nutrient content of food is of only limited value since it is not the same as nutrient value. This is because preparation and processing of food, particularly fruits and vegetables, tend to have a very significant influence on nutrient availability, far greater than relatively minor nutrient differences. Professor Southon emphasised the health benefits of a diet low in fat and energy and high in fruit and vegetables regardless of their source. She was concerned that care should be taken not to confuse people or frighten them off eating a healthy, balanced diet. Since it is the overall balance of the diet as a whole which is important in terms of impact on health, the demonstration of any differences in the nutrient content of organic and non-organic food would not necessarily have any health implications.

Pesticide residues

8.112 The workshop also discussed the possibility of investigating the extent to which organic fruit and vegetables are less likely to have detectable pesticide residues, including multiple residues, than non-organic fruit and vegetables. Clearly all produce, organic and non-organic, is equally likely to be contaminated with residues of pesticides which arise from environmental contamination caused by historic use of persistent pesticides. The rules for organic production, however, allow use of only a few pesticides and the general approach of organic agriculture militates against their use. It is likely, therefore, that organic food will contain fewer pesticide residues arising from use during production than non-organic food (Atkinson et al., 2003). The workshop considered an analysis of US data which indicated that this is indeed the case for fruit and vegetables on the US market analysed for pesticides used in conventional agriculture. This study also found that organic food could contain residues of pesticides which are not allowed to be used in organic production and are not present as persistent environmental contaminants, although it was not clear to what extent fraudulent use was involved, or contamination during production or distribution.

Human Pathogens

8.113 Pathogenic organisms from livestock can contaminate surface waters used for drinking, bathing or irrigation. The increased use of manures in organic systems has led to some concerns of increased risk of product contamination, e.g. directly from field applications or indirectly from contaminated irrigation water. However, Shepherd et al. (2003) concluded that there is no reliable information on any differences in the incidence of zoonoses between organic and conventional farms that use manure. Studies have shown that composting manure and treating slurry, as encouraged under organic standards, decrease the survival of any pathogenic organisms but stacking or long-term storage can also be beneficial. The methods of handling manure between farming systems may not be sufficiently different to produce a consistent effect and, therefore, information on the incidence the organisms is needed before any conclusions can be drawn.

8.114 The Food Standards Agency (Anon., 2003e) have made the following statement about risk of microbial contamination of food: " There is no firm evidence at present to support the assertion that organic produce is more or less microbiologically safe than conventionally farmed produce. However, the Agency recognises that there is a potential risk to food safety from the use of organic wastes in agriculture, both conventional and organic, and, in conjunction with Defra, is carrying out a structured programme of research and risk assessment into the use of all organic wastes on agricultural land."

Health

8.115 There would be substantial challenges in undertaking any research in this area. Not least the problems of framing the question (i.e. what health effects to measure), allowing for confounding factors (e.g. smoking, exercise, alcohol intake), and scale in terms of time and resources. In practice, a study would have to cover a significant part of an individual's lifespan, it would be impossible over that timescale to control the confounding factors, the cost would be high and the time until results were available many years. Therefore it is highly unlikely that a definitive study is either possible or affordable. This leaves a significant problem for retailers and organic organisations in that most consumers will be buying organic food for reasons that are unsubstantiated.

8.116 Following the workshop, the FSA consulted widely asking two main questions:

• would further research into the comparative nutrient content of a selected range of organically and non-organically produced fruit and vegetables make a significant contribution to informed consumer choice?
• would research into the comparative pesticide residue content of a selected range of organically and non-organically produced fruit and vegetables make a significant contribution to informed consumer choice?

8.117 The results of the consultation were not available at the time of writing.

Conclusions

8.118 The following conclusions can be drawn from research in progress:

• approaching 1,000 recent and current organic food and farming research projects were identified across Europe
• there are aspects of many of the studies that are relevant to Scottish conditions, particularly those studying fundamental processes of soil fertility, crop and weed growth, and pest & disease control. The relative importance of different biological processes, crops, pests and diseases will be different because of differences in the soils and climate in Scotland, but a lot should be relevant by careful extrapolation
• research across Europe is dominated by studies on crops and horticulture. Despite this volume of work, conversion of arable and horticulture is under-represented in many States. This is because of the greater costs and risks of conversion of these farm types and because of market uncertainty. There is a dilemma here in that environmental impact following conversion is likely to be greatest on these farms
• work on environmental impact is very limited, despite this being the main policy driver for the support of organic farming
• work on food quality is very limited despite this being the main reason for the purchase of organic food
• studies of upland livestock systems is limited and well below its current percentage of the land area across Europe
• SEERAD research funding is not focused on either resolution of practical producer issues or on determining environmental impact in the hills and uplands which our consultations suggest are priority issues to assist the development of organic farming in Scotland

8.119 The following conclusion can be drawn on food quality:

• Although a significant number of studies on nutrient content have been done, almost exclusively on fresh fruit and vegetables, many were flawed because of poor experimental design and poor control of confounding factors. Organic fresh produce ought to have a lower pesticide content but may be affected by contamination post harvest. Organic fresh produce tends to have a higher mineral and Vitamin C content but this may be at least partly caused by a higher dry matter content. More research is needed to understand these trends, and this is considered by the FSA. Human nutritionists consider these differences trivial and are more concerned about people eating an overall balanced diet. A study to prove or disprove an overall benefit of health from an organic diet would have to be on a long timescale, would involve probably unattainable control of confounding factors and be expensive. It is unlikely that such a study will be funded in the UK at the moment and even if it was it would be many years before data was available. This leaves a difficult dilemma as perceived health benefits are a major reason for the purchase of organic food by many of its key consumers. This is a fragile basis for its future. Perhaps a programme to help consumers better understand the holistic nature of organic methods would help to give a more stable consumer base.

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