A review of current European research on organic farming (OF0171)

This is the final report of Defra project 0F0171. This text has been extracted from the Executive Summary at the start of the attached report. In support of its policy to expand organic farming, MAFF sponsors a programme of research and extension (through Organic Conversion Information Service) to provide information to producers on organic systems of production. The purpose of this review is to provide a comprehensive framework which sets out clearly the content and key results of current European research programmes. The overall objective was to increase the body of knowledge and information available to UK producers and extension workers, and to help direct UK research effort. The priority was to examine northern and western European research programmes i.e. those likely to have the greatest relevance for the UK. Key research institutions, major projects and individual researchers were identified. The data collected were compiled into two research directories. The first was a list of research organisations containing 137 entries. The second was a project list, containing information on 724 individual research projects, including 88 in the UK. The results enabled an overview of the range, content and organisation of organic research programmes. Of the European projects listed (excluding the UK), 40% were related to crop production or soil fertility. A further 14% were on fruit or vegetable production, while 19% were related to livestock or grassland. Results from these studies will be relevant to UK researchers planning new work. Valuable insight was also provided into research methodologies and analytical tools used by European researchers, as well as approaches to dissemination and participatory research. From priorities identified during the compilation of the research directories, three specific study tours were made, focusing on aspects of organic horticulture, arable, and fruit production: - Weed Control in Organic Horticultural and Arable systems - Sustainable Nutrient Management in Organic Field Vegetable Production - Organic Fruit Production. Two technical workshops were also attended and reported: - Designing and Testing Crop Rotations for Organic Farming - Alternatives to the Use of Copper-Based Fungicides in Organic Systems Study tour reports provide detailed information on issues relevant to the UK, results and direction of each research programme. In addition, technical information was collected for technology transfer to UK producers. The research directory and study tour reports are now widely accessible, including on the Web at http://www.adas.co.uk/organic. UK producers, processors, retailers, others in the supply chain, and ultimately the consumer will be the main beneficiaries. Key messages and findings have been provided, some for immediate incorporation into existing production systems. The results will be very valuable to MAFF, research institutes, scientists and research workers when considering current and future UK research needs. Contact with European programmes will help improve the efficiency of UK research programmes, avoid unnecessary duplication and refine research methodology. The work will facilitate further contact between European research workers, to formulate collaborative bids and develop additional sources of funding. It is proposed that the research directories produced by this review are refined and formally updated, on an annual or biennial basis

Organic production in the hills and uplands (OF0319)

It is Government policy to provide a framework in which organic farming can develop, promoting more sustainable and environmentally sound systems of livestock production. Scientific information is required on the development, performance and limitations of organic systems, to facilitate informed decision-making and to aid policy formulation. Using the established organic unit at Redesdale, the overall objective of this project was to evaluate and demonstrate the long-term potential of organic livestock production in the hills and uplands. The experiment was a systems study sited on one discrete farm unit covering 518 ha. Approximately 400 ha had been put into conversion in 1991, so that the experimental period (2002 - 2005) represented years 9 to 12 years of full organic production. Approximately 600 Scottish Blackface ewes were involved in the study, in four self-replacing flocks. At the start of conversion, one original heft (Dargues Dipper) was split to form two sub-hefts of equal stock carrying capacity. One sub-heft (Organic Dipper) was converted to organic production, while the second (Conventional Dipper) continued to be managed conventionally. The two other hefts (Cairn and Burnhead) were both converted to organic production. Beef production was based on spring calving suckler cows, managed in three sub-herds - two a direct comparison of organic and conventionally managed Angus cross cows put to a continental sire; the third consisting of organically managed Angus cows put to an Angus sire. Grassland management was based on a modified ‘Two Pasture’ hill system, integrating native hill, improved hill and inbye land for beef and sheep production. On the native hill, detailed long-term monitoring of vegetation change showed that botanical composition was more affected by previous and current stocking levels, and events such as heather beetle infestation, than by organic and or conventional management. On improved hill land, the underlying trend was regression to rush pasture, leading to reduced productivity on both organic and conventionally managed areas. On the more intensively managed inbye fields, soil fertility levels were adequately maintained on the organic areas, which received only farmyard manure and slurries. Soil pH was more stable than on conventional fields, which received soluable nitrogen fertiliser. Organic inbye fields were sown predominately with short term leys, based on Italian ryegrass and Red or Alsike clover, to provide greater competition for weeds. Production levels were approximately 70% that of fertilised conventional fields. Self sufficiency in winter forage averaged 107% and 93% for the organic and conventional livestock (both sheep and cattle enterprises) respectively. Established infestations of docks production proved difficult to control. Historically, the greatest success was obtained where dock numbers were sufficiently low to enable the plants to be removed manually, or semi-mechanically using a tractor/digger. Data collected as an observation study suggested that for heavy infestations a fallow period and grazing by pigs could have good potential for dock control. Consistent with earlier the phases of the study, sheep production levels were higher in the conventionally managed sheep. Organically managed ewes were significantly lighter and had lower body condition scores at most stages of the production cycle. Average lamb rearing percentages over the three years of the study were 124, 108,108 and 111 for Conventional Dipper, Organic Dipper, Cairn and Burnhead flocks respectively. Average lamb weaning weights (kg) were 31.8, 29.5, 31.3 and 32.9 respectively. Of the total crop, 65% of Conventional Dipper lambs were sold finished at a mean liveweight of 38.1 kg, returning an average of £40.03 (£1.05/kg). The balance (35%) were ewe lambs retained within the flock or sold for breeding. Depending on the flock, the majority of the organic lamb crop (55%-61%) were sold after weaning as stores for further finishing, at a price of approximately £1.15 per kg liveweight. Store hill lambs performed well finishing on an organic lowland farm, returning typical carcass weights of 18.5 kg and a mean sale date of mid-March. An arrangement was entered into to spread the financial risk, sharing the feeders margin between the store lamb producer and lowland finisher. This could be a useful model for wider application, between different farmers or regions with complementary resources. Across all four flocks, the three year average for ewe and hogg mortality was less than 5%. Lamb mortality averaged less than 10%, which compares well with quoted industry figures of 15%-20%. Parasite burdens were low and anthelmintic input was limited to a few individual lambs. No adverse effects were recorded as a result of the long-term withdrawal of clostridial and pasteurella vaccination from one of the three organic flocks (Cairn). Lower levels of performance in the organic flocks could be a multi-component effect of reduced forage availability, lower veterinary inputs, higher levels of subclinical disease etc. However, the most likely factor was the difference in how the improved hill and inbye land was managed under an alternate grazing regime, which allows access by sheep to only half the area of improved hill in any given year. There was little difference in the physical performance of directly comparable organic and conventional sub-herds producing continental cross calves. Conception rates were consistently high, averaging 94%. Calf weaning weights (kg) averaged 292, 297 and 298 for conventional halfbred, organic halfbred and organic Angus sub-herds respectively. Prices achieved (p/kg live weight) for store prices cattle were 102, 127 and 133 respectively. Despite higher prices for organic cattle sold as stores, carcass data from animals sold finished indicated poorer conformation and higher levels of fatness in Angus sired calves. Gross returns were £683 and £648 for continental and Angus calves respectively, representing a difference of £0.10/kg carcass weight (£2.24 Vs £2.34). The main technical issue associated with the organic suckler herd was ensuring an adequate supply of conserved fodder for a 200-day winter. Disease challenges were low and the only veterinary treatment given on a herd basis was a single treatment for lice during the winter period. Average gross margins (£/ewe) before forage costs were £56, £44, £46 and £49 for Conventional Dipper, Organic Dipper, Cairn and Burnhead flocks respectively. Whole flock gross margins averaged £7635, £4609, £5561 and £4315. Lower performance in the organic flocks resulted from a combination of lower sheep numbers, reduced lambing percentages, and the sale of store rather than finished animals. Countryside Stewardship Scheme payments could potentially have increased gross margin in the Burnhead flock to £7915. Gross margins (£/cow), before forage costs, for rearing and finishing enterprises combined were £755, £636 and £527 for conventional halfbred, organic halfbred and organic Angus sub-herds respectively. Forage costs (£/adjusted hectare) averaged £11 and £21 for organic and conventional sub-units respectively. The biggest single contributor to gross margin was stocking rate, which for the organic unit as a whole, was 54% that of the conventional (1.3 LU/adjusted ha Vs 0.7 LU/adjusted ha). For sheep and cattle enterprises combined, gross margins per Livestock Unit (LU), including forage costs, were £451 and £479 for conventional and organic sub-units respectively. The organic unit as a whole returned a gross margin per adjusted hectare 44% less than the conventional (£590 Vs £335). It could be suggested that in reducing stocking rate in pursuit of environmental gain, and adjusting management for better parasite control, the organic system at Redesdale has had to carry a disproportionate financial burden. To offset these effects would require an improvement in output, for example retaining a greater proportion of organic animals for finishing, or entry into an agri-environmental scheme. The period of the study coincides with the last three years of subsidy payments based primarily on the numbers of livestock carried. Historically, stocking rates have been a prime determinant of profitability when measured on a per hectare basis. Under organic management it was not possible to support sheep numbers at previous levels and maintain the same level of individual performance. The advent of support based on Single Farm Payment, further devolves stocking rate from overall profitability. More farmers may be tempted to convert, given that the opportunity cost of conversion is reduced. Decisions will be driven more by the relative strength of the organic market, technical or attitudinal constraints such as feeding 100% organically produced diets, and relative impacts on overall fixed costs. The case for organic farming conferring environmental benefit is clearer in lowland situations than in the hills. In theory, the difference between organic and conventional systems should be less stark under less intensive production prevalent in the hills and uplands. As yet, little has been done to determine the extent to which organic and conventional farmers have adopted practices with positive or negative impact on biodiversity or the agri-environment. Much depends on the attitude of the individual landowner. From a survey conducted by ADAS in Wales, the greatest benefits tend to occur where an organic farm is also participating in another agri-environmental scheme. The extent to which organic, and evolving conventional, systems complement or conflict with cross compliance or Water Framework Directive requirements has yet to be determined. At Redesdale, long-term studies of vegetation change on the native hill, showed a continuing decline in heather cover at the higher stocking rates. Where stocking rates were reduced significantly to accommodate a more balanced organic system there were indications of a positive, albeit slow response in botanical composition. Key to this is the ability to manage moorland in a more proactive way, and to have cattle available to graze Molinia and Nardus. This complementary effect of cattle not only controls the competitive effects of these grassy species with heather, but as demonstrated in other research projects, also benefits sheep performance. If the economics of cattle production becomes very adverse organic farmers may be forced to reduce cattle numbers, which could make some sheep-dominated systems less sustainable. The results indicate that for many hill and upland units, converting to an organic system is not likely to be a matter of minimal changes to existing management. In particular, stocking rate and balance of sheep and cattle at the start of conversion will have a major impact on the management required to achieve acceptable levels of animal performance, financial performance, input reduction and environmental gain. Recommendations were made for further research in the following areas:- Current behaviours and management practices for organic and conventional farmers; the interface of organic farming practice, and that of other agri-environmental schemes; environmental impact at the whole farm, or aggregated farm level; practices to enhance environmental benefit which can be used more widely on organic farms; control of weeds (rushes, thistles, bracken and docks); tightening regulations on non-organic feed allowances; internal and external parasite control; nutrient budgeting; wider cropping options for energy, protein and mineral nutrition; the potential to exploit co-operative effort to overcome technical issues and limitations, and increase environmental benefit

Organic beef and sheep production (OF0147)

This is the final report from Defra project OF0147 To study the potential of organic farming in the hills and uplands, a comparison of organic and conventional production systems at similar stocking rates was made at ADAS Redesdale. This was supported by additional assessments in two further organic flocks, managed at reduced stocking rates, and by data collection on 10 commercial organic farms. Data were provided on physical and financial performance, animal health and welfare, and changes in botanical composition. Specific studies were done to quantify the potential of novel crops for parasite control, the performance of treated and untreated animal manures, and the requirement for trace element supplementation in organic hill stock. The attached main report starts with a detailed executive summary of the methods and findings

Optimising the production and utilisation of forage for organic livestock (CTE0202)

On most organic farms in the UK, forages are fundamental to the application of organic farming practices, particularly where dairy cattle, beef cattle and/or sheep are the major enterprises. Methods used for the production, conservation and utilisation of these forage resources have a major influence on the productivity, efficiency and overall sustainability of organic farms. Forage management and utilisation also have a pivotal role in the maintenance of animal health and in the minimisation of environmental impacts associated with livestock farming. Specific objectives: 1. Extrapolating from published data, to review the requirements for energy and protein across the production cycle for organic milk, beef, lamb, pig and poultry production. 2. To predict the likelihood of meeting all or a minimum proportion of these requirements from a range of organically produced forages. 3. To examine the potential to adjust management or production system to achieve a better balance of nutrient supply and demand 4. To consider likely contribution from alternative forages, and protein sources, as home-grown feeds 5. To assess likely effects on animal health and product quality 6. To develop a database model to predict the potential output and benefits for organic farmers of implementing different options and strategies for forage production and utilisation 7. To determine the environmental losses and gains at each stage of production and utilisation 8. To provide specific guidelines for use by farmers, advisers and policymakers to maximise efficiency in the production and utilisation of forages within a range of organic livestock production systems. Overall, this body of work has indicated that a number of gaps in current knowledge exist such as: the particular suitability of diverse plants and animal genotypes for forage-based organic systems, methods for determining the nutritive value of organically produced forages, trace element nutrition of organic livestock and specific weed and pest control measures in organic crop production. Further dissemination of the outputs from this study, drawn from the five separate work packages in which the work was conducted, will help underpin the sustainability of the organic sector

Efficient use of animal manures within an upland organic system (OF0187)

This is the final report of Defra project OF0187. The attached report starts with a detailed Executive Summary, from which this text is a short extract. The aim of this experiment (1999-2001) was to investigate the agronomic effects of applying treated and untreated farmyard manure and slurry to an organically managed, upland clover/ryegrass pasture. Seven main treatments were imposed in a split plot, randomised complete block design, simulating inputs from organic and conventional systems at ADAS Redesdale. The main treatments were; composted (Treatment A) and uncomposted (B) FYM; aerated (C) and unaerated (D) cattle slurry; ammonium nitrate (E); and a zero nitrogen control (F). A further control treatment (G), to which slurry was applied only in 1996, was added to provide a common control treatment during an earlier phase of the experiment. Target application rates were 150 kg total N/ha for untreated slurry and FYM treatments. Following aeration, the same volume of slurry as for the unaerated slurry treatments was applied. Allowing for losses, composted FYM was applied at a rate calculated to supply 80% (120 kg/ha) of total N compared to the untreated FYM treatment. Ammonium nitrate was used as a conventional control treatment, applied at an annual rate of 240 kg/N/ha. To determine the effect of phosphate and potash, one half of the plots were supplemented when soil levels of these nutrients fell below theoretically optimum levels. Highland Slag and Seagreen K were used as organic sources of P and K, while muriate of potash and superphosphate were used on the conventionally managed plots. Application rates were based on the results of soil analysis, according to standard recommendations for organic (Glenside Organics, Ltd) and conventional (Anon. 2000) production. Overall, the results indicate that high clover swards and the return of major nutrients in slurry and FYM can support a high level of productivity from an organically managed pasture, without the requirement for exogenous fertiliser inputs. Under a conservation system of management, it was clear that soil potassium could be a major limiting factor to herbage yield. However, FYM/slurry maintained an acceptable concentration of herbage K, despite a Soil Index of 0/1. The information generated on nutrient cycling, on output and other measures of productivity raises questions as to the optimum level of soil nutrients required for organic production, the role of soil microbial activity and the potential to better exploit composted FYM. The balance of crop offtake from more modest yields, with nutrients released from the soil, may dictate that high levels of extractable nutrients in the soil may not be a prerequisite for good performance from an organic system

Control of internal parasites in organic livestock without the use of pharmaceutical anthelminthics

Organic systems seek to reduce reliance on external inputs, and develop sustainable methods of production which balance output with high standards of animal welfare. The standards for organic production emphasise preventive control strategies based on grazing management, appropriate breeding and good nutrition. The ultimate goal is to eliminate dependence on anti-parasitic drugs, however this is rarely achieved in practice. The overall objective of this research was to develop organic farming systems, which do not rely on pharmaceutical control of roundworm parasites. Focussing on management and nutrition, the approach was to combine on-farm epidemiological studies, with replicated experiments, in order to develop and demonstrate better systems of control applicable to UK organic farms. The project was a collaborative study involving ADAS, Institute of Rural Science (IRS), Moredun Research Institute (MRI) and Scottish Agriculture Colleges (SAC). Specific objectives: 1. To study the epidemiology of parasitic gastro-enteritis (PGE) on selected 'focus' farms, representing a range of organic systems 2. To quantify the effect of dietary manipulation, novel crops, and drenching with tannins, on the development of PGE in organic sheep and cattle systems 3. To evaluate the role of crop type and pasture larval ecology on the development of PGE 4. To develop the application of alternative approaches on 'focus' farms, under best management practice 5. To ensure effective technology transfer Five commercial organic farms, reflecting a range of production systems (specialist hill sheep, upland beef and sheep, lowland specialist sheep, specialist dairying, and lowland mixed arable / livestock) were selected for detailed epidemiological study. The aim was to assess the level and pattern of parasite challenge, critical points for disease control, and the degree of success achieved with current management practices. The study combined the use of standard epidemiological techniques, with close collaboration of the researchers, participating farmers and their veterinary advisers. Comprehensive epidemiological data were collected over two contrasting seasons (2002 and 2003). Without recourse to routine anthelmintic, control was generally underpinned by grazing management, within the constraints of land/crop resources and diversity of enterprises available for each farm. Role of nutrition: Previous studies, using tightly controlled nutritional protocols and a known parasite challenge, developed a nutritional hypothesis for understanding nutritional influences on the host response to parasites. A replicated experiment was set up to test whether this framework could be extended to organically managed ewes carrying a mixed naturally-acquired infection. Novel crops: A series of experiments were undertaken to determine the potential of several novel crops for parasite control. Parasite pasture ecology: Nematode larvae populations have also been shown to differ between herbage species, potentially due to differences in crop morphology or microclimate beneath the sward (which may affect larval development and survival, or the number of coprophagous or nematophagous organisms at soil level). Several small plot and pot experiments were undertaken to assess the effect of crop type on larval survival, rates of faecal degradation, and soil dwelling invertebrates. Overall, the results from this study indicate that with sufficient diversity of cropping and stocking, it is possible to virtually eliminate anthelmintic usage. However, many farms still face significant difficulties, particularly those systems dominated by sheep. The extent to which control can be achieved by management alone, depends on the farming system, with the greatest opportunity for control in the more mixed, or very extensive production systems. Many of the issues faced by the organic sector are increasingly relevant to conventional farmers where anthelmintic resistance is becoming increasingly prevalent. More integrated strategies are required, not only for organic producers, but also to prolong the life of drenches currently used in conventional farming. Practical recommendations have been derived from this research, and promoted to organic and conventional farmers, based around key messages of system planning, parasite monitoring and maintaining biosecurity

Surveillant assemblages of governance in massively multiplayer online games:a comparative analysis

This paper explores governance in Massively Multiplayer Online Games (MMOGs), one sub-sector of the digital games industry. Informed by media governance studies, Surveillance Studies, and game studies, this paper identifies five elements which form part of the system of governance in MMOGs. These elements are: game code and rules; game policies; company community management practices; player participatory practices; and paratexts. Together these governance elements function as a surveillant assemblage, which relies to varying degrees on lateral and hierarchical forms of surveillance, and the assembly of human and nonhuman elements.Using qualitative mixed methods we examine and compare how these elements operate in three commercial MMOGs: Eve Online, World of Warcraft and Tibia. While peer and participatory surveillance elements are important, we identified two major trends in the governance of disruptive behaviours by the game companies in our case studies. Firstly, an increasing reliance on automated forms of dataveillance to control and punish game players, and secondly, increasing recourse to contract law and diminishing user privacy rights. Game players found it difficult to appeal the changing terms and conditions and they turned to creating paratexts outside of the game in an attempt to negotiate the boundaries of the surveillant assemblage. In the wider context of self-regulated governance systems these trends highlight the relevance of consumer rights, privacy, and data protection legislation to online games and the usefulness of bringing game studies and Surveillance Studies into dialogue

Towards a method for the economic evaluation of environmental indicators in UK Integrated Arable Farming Systems

Integrated Arable Farming Systems (IAFS), which involve a reduction in the use of off-farm inputs, are attracting considerable research interest in the UK. The objectives of these systems experiments are to compare their financial performance with that from conventional or current farming practices. To date, this comparison has taken little account of any environmental benefits (or disbenefits) of the two systems. The objective of this paper is to review the assessment methodologies available for the analysis of environmental impacts. To illustrate the results of this exercise, the methodology and environmental indicators chosen are then applied to data from one of the LINK - Integrated Farming Systems experimental sites. Data from the Pathhead site in Southern Scotland are used to evaluate the use of invertebrates and nitrate loss as environmental indicators within IAFS. The results suggest that between 1992 and 1995 the biomass of earthworms fell by 28 kg per hectare on the integrated rotation and rose by 31 kg per hectare on the conventional system. This led to environmental costs ranging between £2.24 and £13.44 per hectare for the integrated system and gains of between £2.48 and £14.88 for the conventional system. In terms of nitrate, the integrated system had an estimated loss of £72.21 per hectare in comparison to £149.40 per hectare on the conventional system. Conclusions are drawn about the advantages and disadvantages of this type of analytical framework. Keywords: Farming systems; IAFS; Environmental valuation; Economics; Earthworms; Nitrates; Soil faun

Finishing store lambs from organic hill and upland farms OF0119

1. The aim of this study was to assess the economics and constraints associated with home finishing lambs on a range of organic hill and upland farms in England and Wales, and to evaluate the potential for further finishing on registered farms in the lowlands. 2. The current state of the organic sheep sector is briefly reviewed. This identifies problems of scale, limited premia and uneveness of supply as limiting factors to more rapid development of the market and associated production systems. 3. To quanitfy the effect of organic management on financial performance, hill and upland farms were classified under four typical systems, depending on the degree of intensification. 4. Without a sizeable area of improved ground, to which fertiliser and other inputs could have been applied conventionally, flocks based on high hill or marginal hill systems were least affected by switching to organic management. Flock Gross Margin on the marginal hill declined by approximately 7%. 5. On more intensive farms, typified by Welsh hill or upland farming systems, there is greater potential to finish lambs at higher stocking rates under conventional management, and the consequences of changing to organic management are greatly increased. Assuming a 10% premium for fnished organic lambs, deviating from convetional practice to produce store lambs or finish lambs at higher production cost, reduced flock Gross Margin by approximately 12-15%. Without a premium, this deficit increased to 15-20%. 6. The Organic Aid Scheme can make good the likely income loss during the first two years after conversion, when the highest rates are payable. However, in the long-term organic flocks must compete solely on the basis os a premium paid for finished, and ideally, for store lambs. 7. Physical and financial constraints were identified as t wy systems had not developed linking potential production of store lambs in the hills/uplands with finishing on organic farms in the lowlands. These were mainly scale and infrastructure, availability of suitable feeds and the likely level of return to the lowland farmer from a store lamb finishing enterprise. Potential sources of feed for finishing organic lambs were assessed. These include permanent pasture, short-term leys, catch crops, grazed set-aside land and conserved fodder. 8. Integration with existing organic systems of all types was estimated to have the potential to finish an extra 10-15,000 lambs per annum, equivalent to the number of lambs currently receiving an organic premium. 9. Further opportunities to expand finishing capacity on lowland farms were examined. Mixed organic farms are likely to have little or no capacity to finish bought in store lambs, except where overall stocking rates are constrained by insufficient ewe/suckler cow quota, or where catch crops are added to the rotation. 10. The addition of a store lamb enterprise to lowland systems was calculated to increase farm Gross MArgin by 2-3%, depending on the type of farm (dairy, stockless arable, or mixed). This represented a marginal return on capital invested in a store lamb finishing enterprise of 9-24%. 1. The financial risks involved, the availability of suitable labour and fixed equipment, and reluctance to vary arable rotations, make store lamb finishing enterprises less attractive to the lowland farmer. 12. Beyond the capacity to increase the number of certified lambs currently offered by up to 50%, greater opportunities are only likely to develop, when there is a significant increase in land (particularly on arable farms) entering conversion

The effect of organic farming systems on aspects of the environment - desk study OF0123

Key Conclusions 1. The crop rotations of organic systems maintain landscape diversity and biodiversity whilst the maintenance of field boundaries on organic units produces benefits to a wide range of organisms. 2. Inorganic nitrogen fertilisation and herbicide treatments of conventionally managed grassland has reduced the floral diversity of permanent pastures and maintained the low diversity of re-seeded pastures, greatly reducing their value as wildlife habitats. 3. Pesticide use is responsible for the removal of food sourcesfor birds and mammals in the form of weeds and invertebrates, as well as removing whole populations of potentially beneficial insects. 4. The majority of water pollution incidents from farms are caused during storage and spreading of cattle and pig slurries. A higher proportion of organic cattle and virtually all organic pigs are kept on solid manure systems and therefore are les of a risk. 5. The nitrogen balance of individual 'conventional' and 'organic' systems will depend greatly on the circumstances and management practices of the individual farms. Consequently it is not possible to generalise that one system is always better than the other in terms of nitrate leaching risk. With this qualification the literature does indicate that generally, organic systems offer less risk of nitrate leaching. 6. Organic systems are less likely to cause loss of phosphate into surface and ground waters. Both leaching and loss in eroded soil are likely to be reduced. 7. Organic management practicess such as rotations, the regular use of manures and non-use of pesticides usually increase soil organic matter contents. 8. Organic practices are likely to increase earthworm numbers compared to conventional systems. The increased numbers are universally acknowledged to benefit soil fertility although such effects are difficult to quantify. 9. Soil erosion is less of a problem on organic units. 10. Accumulations of copper and zinc in soils are much reduced in organic systems because organic pig and poultry producers do not supplement feeds with these metals as growth promoters. Copper fungicides are more widely used on organic farms and their use should be carefully monitored to prevent harmful effects. 11. The practices adopted by organic farmers can reduce emissions of nitrous oxide and methane. Ammonia emissions will not necessarily be less in organic than in conventional farming. 12. Organic farmers adopt practices which benefit the landscape. They maintain and introduce features largely because they are required by the Organic Standards to do so. They introduce such management practices because they are technically necessary for successful organic production