soil protection and soil quality assessment in the ec

The Science of the Total Environment, 129 (1993) 219-239 Elsevier Science Publishers B.V., Amsterdam

219

Soil protection and soil quality assessment in the EC

P.J.A. Howard

The Institute of Terrestrial Ecology, Merlewood Research Station, Grange-owr-Sands, Cumbria £~AI" 6JU, UK

ABSTRACT

The main threats to soils are: extension of urbanization, acidification, accumulation of pollutants, nitrate in groundwater, loss of organic matter and deteriorating soil structure, soil compaction, and erosion. The latter is espedally Lrnpo~apt ;a seuthern EC countries. Dif- ferences in the approaches adopted by different countries reflect differences in the nature and perceived seriousness of soil problems and the nature of the legislatory system. In particular, differences in the approaches of the Netherlands and the UK are discussed. The concept of 'soil quality' is discussed in relation to these two approaches. Suggestions are given for an ecologically based soil protection policy. This paper discusses current soil protection policies and their development in the EC, and the evolution of the associated concept of'soil quality'. It does not deal in any detail with the restoration of soils which have been degraded by the inadequacy of past policies or their implementation. Emphasis is given to northern EC countries because they have been especially active in the development of policies which protect land and soils.

Key words: soil protection; soil quality; assessment; northern EC countries; policy implementation

HISTORICAL INTRODUCTION

In Europe, the first moves towards the development of a soil protection policy were made by the FRG and the Netherlands. In 1985 the FRG published its Bodenschutzkonzeption, which is essentially a set of principles that the Federal Government would like to see adopted into the legislation of the Linder.

In October 1986 a symposium was organized jointly by the senate of Berlin and the Commission of the European Communities (CEC) to discuss the scientific basis for soil protection in the EC [1]. The Fourth Environmental Action Programme of the EC, submitted to the Council of Ministers of the EC in 1986, includes the development of an overall Community policy to protect soils. Specific actions are proposed to tackle the three main causes

220 P.J.A. HOWARD

of soil degradation, i.e. (i) the contamination of soils by harmful substances of various origins; (ii) the degradation of the physical structure and of the chemical and biological status of soils; and (iii) the misuse of soil resources by inappropriate activities [2].

In January 1987 the Dutch Soil Protection Act became operative, this was the first explicit soil protection legislation in north-west Europe. Also in 1987, The Parliamentary Assembly of the Council of Europe (CoE) adopted Recommendation 1048 on the consequences for agriculture of current soil degradation. It recommended that the Governments of member states give new impetus to their soil protection policies by combining the quantitative aspect with the maintenance of soil quality and take all appropriate measures against erosion damage.

The change in the climate of opinion in Europe during the last 10 years has arisen from a recognition of"

(1) the fact that erosion is now a significant problem in some north Euro- pean countries and the entry into the EC of countries from southern Europe with long-standing erosion problems [3];

(2) a number of other threats to the maintenance of the productive potential of the soil resource, e.g. heavy metal contamination, acidification by acidic deposition [4];

(3) the role of soil in mediating other pollution problems, e.g. nitrate contamination of ground waters;

(4) accelerated changes in ecosystems resulting from soil eutrophication (e.g. in the Federal Republic of Germany, the Netherlands, Denmark);

(5) increased sealing of soils by urbanization, industrialization, and roads.

These pressures have made governments recognize the importance and fragility of the soil resource and the need for policies to maintain that resource.

CURRENT SOIL PROBLEMS IN THE EC

Although there are differences between countries in the relative importance of the various threats to soils, there seems to be general agreement on the nature of the important threats, which are: extension of urbanization and infrastructure, acidification, accumulation of pollutants, loss of organic matter and deteriorating ~oi! structure, soil compaction, and erosion. Nitrat~ in groundwater is also a problem. Due to the predominantly sloping terrain and the adverse climatic conditions in southern Europe, soil erosion is the domi- nant cause of soil degradation there and is related to all losses of soil productivity [5]. However, data for southern European countries are difficult to

SOIL PROTECTION AND SOIL QUALITY ASSESSMENT IN THE EC 221

obtain. Italy, for example, is probably the only developed nation with no adequate administration for collecting information on the 'stock-taking' aspects of the land or inventories of changes of use, or of the area and income of farms [6], and as recently as 1988 there was a lack of information on the extent of natural and man-induced soil changes. Furthermore, soil protection was not being discussed on a public scale, although there hav~ been a few relevant academic seminars and conferences (J. Wollesen, personal communication). Most of the impetus for soil protection research seems to come from northern European countries.

The covering of soils by urbanization and industrialization is a matter of concern in many European countries. Not only does this seal the soils, but usually the topsoil is removed beforehand. The percentage of the soils of various countries which are affected are given in Table 1.

Soil erosion is a process which occurs naturally, but its rate increases to the point where it becomes a problem when the vegetation cover is disturbed. In southern Europe in particular, a tendency towards increased deforesta- tion, more rapid crop rotation shorter fallow periods, the introduction of monocultures and overgrazing are all practices which can accelerate erosion.

In Mediterranean countries more than 80% of the land is potentially erodi- ble and about 40% of the land of Spain and Greece has had its productivity seriously reduced'. In Italy, landslides are a problem. A Mediterranean-wide assessment oferosion risk at a reconnaissance level is being carried out under the CORINE project of Directorate-General XI of the CEC. However, larger-scale and more detailed surveys are required for planning purposes, both in Mediterranean and non-Mediterranean countries. According to

TABLE 1

Percentages of land under different uses in various EC countries (see Ref. 8)

Country Urban Agriculture Woodland Other

Belgium 14.6 50.6 20.4 14.4 Denmark 9.2 69.4 ! 1.3 10.1 Netherlands 15.0 64.6 8.8 11.6 UK 8.0 78.2 7.9 5.9 France 4.9 61.2 28.3 5.6 FRG 11.8 54.2 29.5 4.5 Italy 4.2 66.2 21.0 8.6 EC 6.8 64.2 21.6 7.4

222 P.J.A. HOWARD

Foumier (8), average rates of soil erosion in Europe are (in mt/km 2 per year):

(1) Low-relief regions in northwestern Europe (2) Mountain regions in France (3) Small valleys in the Alps and Appenines (4) Albanian mountains

24 180-250 2500 4000

Rates as high as 23 000 mt/km 2 year have been reported in mountainous watersheds ia Greece [9], where some 30% of cultivated land is subject to increasing erosion [6]. The relationship between tourism developments and soil erosion in Greece was discussed by Cassios [10].

The situation is undoubtedly less serious in northern Europe, but an increasing amount of pasture land is being brought under cultivation, crop rotations have been shortened and~ in some regions, there is a tendency towards monocultures such as maize [11], which leaves soil bare until late in the year with consequent risk of erosion. In mountain areas, forest death and tourism are also increasing the erosion problems. It is difficult to identify the scale of the erosion problem with any accuracy. In France, 5 million ha of land are subject to erosion, while in Belgium the figure is 600 000 ha [3]. In FRG soil erosion has long been recognized as a problem and has become especially noticeable over the last 10 years. In England and Wales, about 37% of agricultural land (2 million ha) is threatened by an unacceptable degree of erosion [3].

Soil acidification is one of the major current threats to soils in northern Europe [12]. It is a process which occurs naturally at rates which depend on the type of vegetation, soil parent material and climate. It can be accelerated by man's activities, for example by the choice of tree species, by the use of fertiilizers and the draining of soils and especially by the release into the atmosphere of oxides of sulphur and nitrogen. Ammonia, from intensive stock breeding, has an indirect and fairly localised effect [11]. Increased acidity of percolating water can lead to aluminium ions being leached out from rocks and soils and into watercourses and in waters of low pH and low calcium content dissolved aluminium is highly toxic to salmon and trout. Forestry can increase this effect, as rainwater collected beneath a conifer canopy con- tains much more sulphate than the rainfall itself, due to the collection of air- borne sulphate by tree canopies.

Heavy metals, chiefly zinc, copper, nickel, lead, cadmium, chromium and mercury, are found in domestic sewage sludges and wastes. Over the last 10-15 years, every EC member state has been considering seriously the maximum heavy metal content which is tolerable in farmland [13]. A Joint EC Directive gives maximum ranges of heavy metals in soils. These may be ex-


ceeded only in exceptional conditions, but otherwise should not even be reached. In FRG, a Federal Decree of 1982 controls the use of sewage sludge. In 1988, about 30% of sewage sludge was used on agricultural land and additional problems with organic compounds such as dioxins were becoming evident (E. Fleischhauer, personal communication). France is in the process of working out technical standards for the use of sewage s:~Jdge and standards for determining the levels of trace elements in soils before the first spreading and every 10 years thereafter. In the UK, about half of the domestically-produced sewage sludge is used for agricultural purposes according to a code of practice which aims to control heavy metal inputs to soils by requiring compliance with guidelines which in future will be in line with the EC Directive [14]. A major problem is that once heavy metals get into soils they may persist for thousands of years [15].

Attitudes to the use of pesticides vary. In 1984, in some countries, there appeared to be little concern about the problem in Belgium. In France, some lines of research had been defined to study the way in which pesticide residues act in certain types of soil corresponding to certain situations, and in particular to follow the effects of run-off [14]. However, by 1988 the use of pesticides in FRG was c~asing problems in soil water and ecosystems. Contents of pesticides and their metabolites often exceeded the EC norm of 0.1 x ~ in ground water. Biodegradable pesticides in soils reach an equilibrium with the soil water, so low values in soil water require low values in soils. For example, with atrazine if only one-thousandth of the permitted use level finds its way into the soil the amount in the soil water is greater than the permitted level. In FRG, some pesticides were found in summer rain in quantities greater than 0.1/zg/l (E. Fleischhauer, personal communication). Some 300 organic compounds are applied on a large scale in EC member states [16]. In the Netherlands, 31 compounds have been placed on the 'black list' of compounds which must not be used in the protection zones for drinking water supply. In addition, there is a 'white list' of 206 compounds which may be used in drinking water areas if the directions on the label are followed strictly.

The application of liquid manures and other agricultural residues to soils causes problems because of their contents of nitrogen and phosphorus. There are two main problems: (i) the risk of losses of nitrate into shallow groundwater; and (ii) saturation of the soil with phosphate, which may also move into the groundwater. These problems were discussed by Sauerbeck [13] and Beard [17]. Nitrate in groundwater is a particular problem in the Netherlands, where they try to solve the problem by creating buffer zones in which the spreading of manure is prohibited. The size of a buffer zone is decided from models of nitrate movement, e.g. ANIMO [18]. Deposiuon of atmospheric ammonia and nitrogen oxides on nutrient-poor soils can lead to

224 PJ.A. HOWARV

changes in the vegetation which are considered to be undesir~ble and hence are regarded as a form of degradation, e.g. in heathlands in the Netherlands [19].

Eutrophication was also causing some concern in FRG in 1988. Not only were natural ecosystems decreasing in extent as a consequence of increases in other uses of the land, but general atmospheric emissions were changing their ecological status. The input of nitrogen from the atmosphere was of the order of 30-50 kg/ha per year. Some forest scientists consider that spruce forest, for example, can use only 20-30 kg N/ha per year, so that there is an excess in such soils (E. Fleischhauer, personal communication).

Many of the changes in agricultural practices which have occurred over the past 50 years have reduced the amounts of organic matter in soils. Many people have identified the causes as being related essentially to economic and fiscal policies. It has been noted that the carbon contents of some Belgian soils are decreasing, and in France the phenomenon is noticeable particularly in the south. In the UK, the weakening of soil structure due to loss of organic matter is a fairly general problem of arable land. It has been estimated that the critical organic matter level in such soils is about 2%, but in many cases the actual level is 1-1.5%.

The tendency to use increasingly heavy machinery on both agricultural and forest land, particularly in wet conditions, leads to the formation of compacted layers and hence to the poor development of vegetation. In the UK, moderate or severe compaction is common on heavy soils under arable and intensive grassland cropping systems. Other, lighter but intensively-used, land is also susceptible to compaction though in such soils corrective measures are easier.

Land contaminated by past activities is a major problem in many countries. In Britain, for example, it is estimated that up to .50 000 ha of land may be contaminated with toxic wastes [20]. In Denmark, planners estimate that 60 mt of contaminated soil are scattered throughout the country. The Danish government and private sector interests plan to start a thermal treatment plant in 1991 to remove most of the hazardous compounds from soils. It would take 30 years and D.Kr. 7 billion (£650 million) to process all of the contaminated soil in Denmark. Other countries, including FRG and Holland, are exploring similar methods [21]. The latter two countries have h~d problems with contaminated soils for some time, and these gave a special in~petus to their search for soil quality standards and their concern for soil protection.

CURRENT SOIL PROTECTION POLICIES IN THE EC

The pressures described above have together resulted in an awareness of the importance and the fragility of the soil resource and the need for policies


to maintain it. However, there are differences between countries in the approaches being taken which reflect variations in the nature and the perceived seriousness of soil protection problems between countries and in the extent of the protection afforded by pre-existing legislation.

Thus, soil policy in the Netherlands is embedded in general environmental policy which aims to ensure that protection of one part of the environment should not lead to deterioration of another part. The task of preserving those properties of the soil which are important' for various possible present and future functions led to the so-called 'multifunctionality' concept, which aims at keeping all options open for future generations. In January 1987 the Dutch Soil Protection Act became operative. The provincial governments apply the Act and deal with appeals, not necessarily uniformly. They are more likely than the central government to be sympathetic to appeals on grounds of economics. The number of soil and groundwater protection areas which have been declared varies from province to province, because too much protected land in a province is an economic restriction.

In the FRG the concept of soil protection is integrated into legislation embracing protection of nature and the landscape, air pollutant abatement, noise prevention, protection of water resources and waste disposal. The soil protection programme has seven basic principles: prevention (of soil damage), the 'polluter pays', co-operation (between Ministries and sectors of industry), careful management of fertile land, use of soil condition as a pollution indicator, the social function of soil ownership (stewardship of soil). This approach also states that irrespective of their use to mankind, natural resources are worth saving for their own sake [22]. It is also stressed that more must be done to use land for purposes to which natural conditions of the site are best suited, and to reduce the demands made on soil. Any remain- ing undisturbed areas, or areas still in an almost natural state, should be safeguarded. The Federal Government recognizes that international and intergovernmental co-operation will be necessary, partly because of transborder pollution and partly to avoid unequal economic competition, particularly in the industrial and agricultural sectors.

A catalogue of measures on soil protection (Massnahmen zum Boden- schutz) was adopted by the Federal Government in December 1987 and published in January 1988. However, the Ministers of the Lander decided not to move quickly on this issue because of the required extent of change in policy-making and legislation. There was little political support for action. The lack of action on these measures does not mean that soil protection is being neglected totally. For example, in North Rhine Westphalia soils and water supplies are being monitored for pollutants and for advisory work. A provincial soil information system is needed to promote this work further [23,24]. The Wasserhaushaltsgesetz (Water Management Act) requires the Lander to implement regulations in water conservation areas restricting the

226 PJ.A. HOWARD

types and intensity of farming, amounts and timing of fertilizer and plant protection applications, to ensure that water supplies are not polluted. The different Lander have implemented these regulations in different ways with different provisions for compensating farmers for loss of income [25].

Apart from Article L 421.1 ff of its Forestry Code, which concerns erosion in certain areas, France does not have explicit soil protection policies. French policies which involve soil protection are concerned only with agricultural land. Priority has been given to the study of heavy metals because their accumulation in soils presents a serious problem, and they are easy to measure. However, plant protection products (pesticides, fungicides), erosion, and other forms of physical degradation are also being considered. Currently, in France, special attention is being paid to statistics on the use of manure, pesticides etc., under different types of agriculture, and to the different soil functions [26].

Danish soil and water protection are focussed on the eutrophication of ground and surface waters. There is also concern about acidification of terrestrial ecosystems, largely through dry deposition of ammonia and nitrogen oxides and of the acidification of groundwaters through oxidation of pyrite in shallow sandy aquifers. Although heavy metals and pesticides are not currently a problem, they are being controlled and monitored. Soil protection is dealt with under the provisions of the Environmental Protection Act, last amended in 1987, and is oriented strongly to the prevention of soil contamination. No actual quality standards are set, and no attempt is made to define 'good quality' soil, air, or water. Inherent within the Environmental Protection Act is the concept that land use should be related to the capacity of the land to support it, and that the nature of the land should influence land use.

The UK approach is different, and there is no explicit soil protection legislation. Instead, measures which protect soils, either explicitly implicitly, are built into the general environmental legislation in ways that are discussed in the next section.

In Belgium the state, via various departments of the Ministry of Agriculture, has most control over agricultural policy and the general organisation of agriculture, horticulture, animal farming, and related research. ~.he rbgions exercise control over rural renovation, land division, policy on water, hunting, fishing, and forestry. This division of responsibility generates many equivocal situations with respect to establishing a more ecologically-based agricultural policy. This is a source of conflict, as the responsibility for the protection of the environment and for the reorganisation of rural areas lies wi~h the regions, whilst the organisation of the agricultural economy, e.g. regulations for the use of plant protection products and


animal feed supplements, is generally the responsibility of the Ministry of Agriculture [6].

The constitution of the Portuguese Republic is one of the most extensive in the world with respect to the environment, but much of the basic legislation remains undone and there are organizational problems [6] (see the contribution of Borrego, in this issue). In Spain, the division of responsibilities among many bodies and departments leads to confusion and inefficiency, and schemes to protect the environment may well fail through lack of co- ordination. Some attempts hav~ been made to bring together bodies concerned with environmental issues, but they have not achieved as much as was hoped [6].

In Greece, various administrative entities dealing with questions concerning nature and environmental planning were brought into being by Law 360/1976, but by 1987 they had not become integrally operative~ even though the country has to deal with varying degrees of decline in the state of the environment. The National Council issued several rules, but only the decision relating to atmospheric pollution was totally complied with [6] (see also the article of Klidonas in this issue).

In Italy, a bill to establish an effective Ministry of the Environment was passed as recently as May 1986. The regions have wide powers with regard to land use planning, nature conservation, and protection against pollution. The 100 provinces and 8053 municipalities also have responsibilities, which often overlap. 'Seen as a whole the administrative structure in Italy appears unsatisfactory, both centrally and locally. It needs to be revised, as it was structured at a time when environmental problems were of much lesser importance, both socially and technically' [6].

Of course, pollution does not recognize political frontiers. Outside the EC, apart from measures for protecting forest soil in mountainous areas with a view to preventing avalanches, current Swiss legislation is concerned largel~ with controlling pollution, protecting farmland, and with using land effi- ciently. However, they have an extensive research programme which looks at soil from three different viewpoints: (i) soil as a natural object; (ii) soil as building ground; and (iii) soil as an economic commodity and a legal object [27]. The Swiss philosophy has much in common with that of the Dutch, and they have taken up the concept of multifunctionality.

On 27 June 1985 the Council of Environment Ministers of the European Communities adopted a Directive 'on the assessment of the effects of certain public and private projects on the environment'. This Directive, also known as the Environmental Assessment (EA) Directive, was notified to the Governments of Member States on 3 July 1985. Under article 12(1) the measures necessary to comply with the Directive had to be taken by 2 July

228 PJ.A. HOWARD

1988. Article 3 of the Directive requires that an environmental impact assessment will identify and assess in an appropriate manner the direct and indirect effects of a project on various factors, including soil, water, air, climate and the landscape. The background to the EA Directive has been reviewed by Turnbull and Aitken [28].

SOIL PROTECTION IN THE UK

Although there is no explicit soil protection legislation in the UK, a number of laws and regulations do provide implicit protection, thus land ires been protected under legislation covering the creation and management of National Parks, Nature Reserves etc., which has, to a greater or lesser extent, protected the soils within the areas of the Reserves or Parks. Landscape and nature conservation in the countryside is achieved through the negotiation of voluntary management agreements between the relevant authorities and the land owners or occupiers.

The primary responsibility for the formulation and implementation of land-use policies for urban and rural areas rests with the local planning authorities. The Town and Country Planning Act 1947 introduced a comprehensive land-use planning system for the UK, and its provisions were incorporated into the subsequent Town and Country Planning Act 1971, applicable to England and Wales (and, for Scotland, the equivalent 1972 Act). The use of land for agriculture or forestry is specifies!ly excluded from the definition of development in the Town and Country Planning legislation, the main aim of which is to control development, i.e. any building, engineering, or other works or material change of use [29]. An important requirement of the Town and Country Planning Act is that in deciding whether or not to give planning permission, the planning authority 'shall have regard to the development plan for the area and to any other material considerations'. The value of the soil for any purpose in any location may be regarded by the planning authority as a material consideration if the value or quality of that soil could be demonstrated adequately. For more than 20 years, agricultural land in the UK has received some protection from non-agricultural development as planning authorities have attempted to restrict building on Grade 1 and 2 land. From 1965 the implementation of this policy was made possible by the 5 grade MAFF Agrii:Uifiif~ii Land Ciassilication system [30,31].

Guidelines on the maximum amounts of the most common toxic elements (metals) which can be added to soils over a long period are agreed between the Ministry of Agriculture, Fisheries and F¢od (MAFF) and the Depart- ment of the Environment (DOE). Toxic element conce~;ations in sewage sludge and in the soils to which it is applied are monitored to ensure that these maxima are not exceeded [29].


In their reviews, Lummis [32] and Kromarek [14] concluded that the concept of an overall and all-embracing policy of soil protection is alien to thought in the UK. The pragmatic approach to problems which has govern- ed legislation and attitudes for very many years dictates against a conceptual philosophy such as appears to be inherent in a policy for soil protection. Lummis [32] stressed, however, that the problems of pollution and damage to soil are not being overlooked or treated with less than due regard. On the contrary, he concluded that all the forms of actual and potential harm to soil discussed in his study were subject to controls and measures of one kind or another, ~II aimed at protecting or restoring soil and all making the best use of it. 'V•hether more co-ordination of such policies would improve the end result is a reasonable question to ask: some think that there is such a need. There are no signs in present official thinking that this kind of initiative would be pursued at present' [32].

However, Lummis [32] drew attention to the fact that over three-quarters of the surface of the UK (or at least of England and Wales) is excluded from planning control by virtue of being under agriculture or forestry. He noted that there is increasing evidence that the exemption of most f0hns of agricultural and forestry development is being challenged, and that some change would be needed if the system were to be considered to provide an effective policy for soil protection. Any proposed change of use of a piece of land from agricultm'e and fore~L¥ w~u~, of :ourse, ~fing it 'dllder planning control. Subsequently, the UK recognized the need to establish the basic principles of soil protection with a view to optimizing the management of the soil resource, and DoE commissioned a report on the principles of soil protection in the UK [33].

The UK government now regards the critical load and target load concepts as having important roles in the setting of future emission levels and emission control protocols for acidic pollutant gases. DoE has formed a Critical Loads Advisory Group to advise it on the setting and mapping of critical loads for acidi~y, sulphur, and nitrogen for natural vegetation communities, soils, and surface waters. Critical load and target load maps for sulphur will play an important part in the forthcoming renegotiation of the sulphur protocol.

With regard to the EA Directive, the DoE working party's principal con- clusion was that the requirements of the Directive can be met within the context of the existing planning system, and that the implementation of the Directive would provide a valuable opportunity for rationalising the existing planning activities and advising on good practice. The list of developments for which assessment is not obligatory includes many potentially-damaging activities, mainly industrial. In general, it appears that the Gow, rnment does not foresee that it will be necessary to make the carrying out of formal

230 PJ.A. •OWARD

assessments mandatory in such cases, the existing planning legislation is considered to be adequate. However, it was proposed tha~. the appropriate Secretary of State should have the power to direct that an assessment should be carried out in a particular case if it is deemed to be necessary. The UK Government hopes that developers will use these procedures voluntarily.

PRESENT AND FUTURE ACTION IN EC MEMBER STATES

Over the years !990-!993, the Federal German Governnlent plans to provide DM 65 million for research into soils, including water resources. DM 63 lnillion has already been spent on a number of projects.

In July 1990 the Dutch government allocated an additional billion Dutch guilders (about 310 million) a year to a new version of their country's 20-year National Environmental Policy Plan (NEPP). The revised plan, which Will absorb up to 16 billion Dutch guilders/year by 1994, represents an accelerated implementation of the measures in the original NEPP so that the long-term objectives can be achieved earlier. The Dutch regard this as Europe's most comprehensive environmental initiative [34].

The Netherlands Defence Force has launched Europe's first Defence En- vironmental Programme (DEP) to tackle the growing problem of soil pollution. It will complement the NEPP. A £200 million fund has been established to help the DEP with its first assignment, testing soil samples taken from some 200 polluted sites around the country. Military personnel, assisted by government scientists, will clean up and redevelop at least one-tenth of the most heavily-polluted areas [35].

The British government has introduced a 5-year pilot scheme to reduce nitrate levels in water. Farmers in ten selected areas are being offered between £55 and £380/ha per year to reduce the use of fertilizers and manure and to switch from cereal crops to grassland and trees. In 1990 farmers have until July 31 to enlist in the scheme, and will be expected to start farming in a 'nitrate-sensitive' manner from August 1. There is also a requirement to maintain adequate crop cover in the autumn to prevent nitrate leaching. Farmers not taking part in 1990 can begin in 1991.

A proposal by the EC to control t ~ disposal of chromium-contaminated sewage sludge to agricultural land has yet to be discussed by Environment Ministers. The proposals are likely to be opposed by the UK, which regards them as being unjustifiably strict. Some UK soils have higher natural chromium concentrations than the limits prescribed by the new draft [36].

New rules on waste, water pollution, and battery recycling were agreed by EC Environment Ministers on 7-.8 June 1990. Revisions to the 1975 'framework' Directive on waste have been agreed, but the final text is not yet available, and in any case may be amended because the Directive has now

SOIL PROTECTION AND SOIL QUALITY ASSESSMENT IN THE EC 23 !

been passed to the European Parliament tor a second reading. The latest Directive dealing with discharges of 'black list' substances into water was adopted by Environment Ministers, and is due to come into force by 1 January 1993. The Directive sets environmental quality standards and discharge limits for four black list substances. Under the Directive defigned to promote the recycling of batteries containing mercury, cadmium and iead, such batteries will have to be labelled to indicate their suitability for recycling and their heavy metal content. Alkaline manganese batteries containing more than 0.025% mercury by weight ~vill be banned from 1 January 1993, although a higher value (0.05%) may be ~]lowed for batteries for use in specified extreme conditions [37,38].

A long-awaited EC document on a waste management strategy for the European Community was discussed by Environment Ministers in September 1989. The paper's key proposals, which are set in the con~e×t of the removal of na*.;onal barriers to trade in 1992, are for a major legislative programme to ha__rmonize incineration and landfill standards, an emphasis on disposing of wastes close to the point of production, additional measures to promote recycling, and the beginning ~f a new programme on the clean-up of abandoned landfills [39].

It would take a brave person to attempt to predict the effects of the Single Europeaa Act on soil protection policies of member states, because of the complex interacting factors which will be involved. Not least of these factors will be the economic effects of the setting up of the internal market in 1992 [40]. In theory, important aspects of environmental policy are already the subject of Community legislation, and it will be increasingly difficult for member states to introduce their own policies unless these fit into EC policy. In practice, problems which are being experienced by the Dutch and Federal German governments in implementing their own national soil policies foreshadow similar problems on a larger scale. Much will depend on the way in which any EC Directive on soil protection is framed and on the effects of other environmental Directives.

In September 1992 a European Conference on Integrated Research for Soil aad Sediment Protection is to be held in Maastricht, the Netherlands. It will be concerned with the relationships between soil research, soil protection policies, and laws which provide direct and indirect protection for soils, as well as the assessment of soil quality and problems which arise from soil contamination. This conference has the potential to be a watershed in such issues.

SOIL QUALITY

Discussions about 'soil quality' and its definition appear to have come

232 P.J.A. HOWARD

chiefly from Dutch soil protection policy, the central aim of which is the maintenance of 'good soil quality'. These, in turn, arose from the Dutch problems with contaminated soils and their cleaning, and the necessity to set standards which should be achieved by the cleaning process.

Other countries have not been so concerned with the definition of soil quality and the setting of standards and reference values. In the Federal Republic of Germany, for example, the Massnahmen zum Bodenschutz does not contain a list of soil quality standards. There are scientific, as well as legal, difficulties in the setting of soil quality standards. Furthermore, the setting of soil quality standards differentiated according to soil types would require an official map of suitable scale covering any area of concern. These are not yet available (R. Schier, personal communicaion). At present the only standards and limits are those in the Klarschlammverordnung (Sewage Sludge Ordnance), which sets limits for seven heavy metals.

In France the term 'soil quality' is used in a very broad sense, covering both the phenomena of physical, chemical, and biological degradation and problems of toxicity, heavy metals, and pesticides [41]. In Denmark no actual soil quality standards are set, although the Environmental Protection Act does enable the Minister to do so. No attempt is made to define 'good quality' soil, air, or water. In the UK the concept of soil quality is fairly broad, and is related to the grading of land under the MAFF Agricultural Land Classification system [30,31].

In the Netherlands, it has been suggested that reference values for a 'good soil quality' should be such that the soil poses no harm to any use by human beings or animals, can function in natural cycles without restriction, and does not contaminate other parts of the environment [42]. For heavy metals and organic chemicals, Vegter [43] assumed a linear relationship (which was forced through the origin) between the amount of a heavy metal and the soil clay and organic matter contents, and calculated a reference value for an 'average soil'. In a discussion paper circulated by the Dutch Ministry of Housing, Physical Planning and Environment, the maximum of the range of reference values for a given substance was proposed as a provisional reference value for a 'good soil quality'. However, Lexmond et al. [44] considered Vegters approach to be unsuitable and calculated new 'average background values' (the A valu~ of the Dutch clean-up guidelines). These were subsequently converted into '~gJl quality reference values', and formulae were produced which enabled the reference values to be adjusted for specific soils with different clay and organic matter contents [45,46] although Lexmond (personal communication) did not like these formulae.

The Dutch soil quality reference values have not so far been based firmly on eco-toxicological evi~dence. The ecological risk of a chemical in the environment can be defined as the probability that a random species in a large

SOIL PROTECTION AND SOIL QUALITY ASSESSMENT IN THE FC 233

community is exposed to a concentration of the chemical greater than its no- effect level. The risk can be estimated if both the distribution of environmental concentrations and of no-effect concentrations are known. Conversely, a value in the environment ('advisory value') may be estimated such that the risk does not exceed a prescribed threshold. Van Straalen [47] derived formulae using a 5% risk threshold (including an uncertainty margin to allow for errors ofestimation). Using data for soil invertebrates, advisory values were calculated for maximal concentrations of cadmium, lead, lindane, aldrin, and atrazine in a 'clean' soil. Apart from lead, the largest difference between the advisory values and the reference values from the Dutch Ministry of the Environment was for cadmium (0.16 and 0.8/~g/g, respectively). The advisory value of lead was larger than the reference value (112 and 85 ~g/g respectively), which suggests that lead in soil is not such a problem to soil organisms when concentrations are moderately above background levels.

The natural variability between and within soils and the variation in the impact of a given stress on soil processes and functions mean that there is no single parameter which can be used to define 'soil quality' or 'adverse changes'. A series of reference parameters would be needed, and even given such a series there is no single set of reference values for those parameters which might define 'quality' [12].

The UK view [48] is that there are both theoretical and practical objections to the Dutch methods for setting soil quality standards, even if it were possible to agree on why they are needed and how they should be used. The theoretical (scientific) objections are: (i) the values are based on 'average background' concentrations; the local background concentrations found in different parts of the UK vary markedly and no single 'average background' value can be chosen; (ii) uncertainties over the adequacy and represen- tativeness of the samples from which the 'average background' values are derived; and (iii) uncertainty in relating the sites chosen to define the average background values to those found in other areas (e.g. sites included in clean- up programmes or derelict land reclamation schemes). The main objections in the context of UK policy are: (i) if judged against 'average background' concentrations, however, they have been obtained, many sites already in use in industrial or urban areas will appear to be 'contaminated' when in fact the contamination presents no risk to their present use; and (ii) the background values do not take either present or future land uses into account, although the actual significance of soil contamination depends markedly cn the use.

From that point of view, it is only feasible, in most cases, to have assessments of soil quality which involve considerations of current or intended use, e.g. the various classifications of the suitability of land for particular crops or of the capability of land to support agricultural use. These involve the

234 P.J.A. HOWARD

comparison of actual soil and land properties with the required values for a range of uses. Although it is not yet formally incorporated into statements of policy, the UK view is that a soil need only to be fit for the immediate use. When that use changes the condition of the soil may constrain the choice of future use. If it does so, then appropriate remedial action can be carried out within the context of land reclamation or site development proposals. However, remedial action may be too expensive or impossible in practice, for example if the soil is contaminated by heavy metals. The potential of such land is therefore limited.

An alternative approach would be to aim to prevent either (a) changes in soils which cannot be reversed naturally or by ecological approaches, or (b) to prevent changes in soils greater than those which occur naturally as a result of natural variations in other environmental factors such as climate. There would be no one reference value for each reference parameter but in (a) the datum could be values for the reference parameters in undisturbed natural soils. It would also be necessary to determine the magnitude of change in the parameters, for particular soils, which can be reversed naturally or ecologically; or, in (b) above, the range of variation in the index parameters which occur as a result of natural environmental variations. Domsch [49] has discussed the approach represented by (b) with respect to the impact of pesticides and heavy metals on soil flora and fauna. It is not possible currently to define the limits of change of most reference parameters which are naturally reversible, or are within the range resulting from environmer~al variation. However, it is possible in some cases to identify qualitativdy changes which arc not reversible naturally, e.g. the accumulation of hea~y metals, or to ide~Rify land/soil uses which produce a range of changes which are not reversible naturally, e.g. construction, extraction of minerals, disposal of certain wastes.

The concepts of buffering capacity and resilience, or reversibility, are related to sensitivity and may also be useful in the formulation of soil protection policies [12]. The cfitica! load approach [50] provides a means of linking controls on the load of a given stress to soil protection by means of cause- effect models. The approach requires mathematical models, but the necessary models are available for only a few stresses.

Blum [51] drew attention to the need to give priority to the international standardization of methods for the evaluation of soil quality, the extension of the existing 1:1 000 000 soil map of Europe to all 22 member states of the European Council, and the preparation of soil maps at a larger scale.

AN ECOLOGICALLY-BASED SOIL PROTECTION POLICY

Given that the desirability of some form of soil protection policy was


recognized, for whatever reasons, it would need to be based on some scientific aims and principles. One impo~ant consideration is that soils are regarded as complex, dynamic systems which perform a wide variety of functions and form parts of ecosystems. Hence, soil protection implies the protection of a complex, dynamic, heterogeneous system and the maintenance ~f the complexity, the dynamic nature, and the variability within and between soils. It should not aim to prevent natural changes, or the natural development and evolution of soils. It should protect soil systems from adverse and undesirable changes resulting from man's influence, but could not aim to protect soils against all man-induced changes in soils. It should not be restricted to soils under particular forms of use. It should aim to reverse adverse man-induced changes in soil systems to take account of soils which have already experienced adverse changes.

Because of the problems involved in the definition and assessment of 'soil quality', the approach which would seek to prevent either (a) changes in soils which cannot be reversed naturally or by ecological approaches, or (b) changes in soils greater tha~ those which o~ur naturald_ly as a result of natural variations in other environmental factors, could form the basis of a quantitative definition but would require the evaluation of a series of reference parameters as noted above. A soil protection policy should seek to avoid or restrict activities which produce irreversible changes and to restore the soil by technological means, if the particular use ever ceased.

The implementation of an ecologically-based soil protection policy, whether by an individual government or by the EC, would require:

(1) A characterization and assessment of soils and their current status; (2) The monitoring of changes in soils over time; (3) The assessment of the impact of man's activities on soils, particularly

the impact of changes in land use and management on their characteristic~ and functioning;

(4) The definition of acceptable loads of man-induced stresses and means of controlling those stresses;

(5) The development of alternative management methods and techniques to reduce the impact of man's activities on soils;

(6) The definition of target values of soil parameters to be used in the rehabilitation of damaged soils.

The impact of man's activity on soils could be included in regulations which implement the EC Directive on environmental assessment. While it might not be possible at present to produce quantitative assessments of impacts on soils, as a first stage soils could be ranked in terms of sensitivity. Critical loads, or acceptable loads, provide a means, of linking a soil protec-

236 PJ.^. HOW R̂V

tion policy with legislation concerning the control of activities which may have adverse effects on soils. The development of less-damaging land management strategies has been referred to as 'optimization' in the Netherlands, where great efforts have been made to develop models for mat- ching nitrate fertilizer inputs to plant demand [52]. Parallel work is in pro- gress in the UK. Another aspect of less-damaging land management would be the introduction of new technology, e.g. wider tractor wheels to reduce the loading on the soil. With regard to target values of soil parameters, the evaluation of the success of any restoration should include reference parameters which cover biological, chemical and physical aspects of soils and their functioning. Wherever possible, reference or target values should be assigned to each parameter.

ACKNOWLEDGEMENT

This paper is based substantially upon a report (see Ref. 33) of a study funded by the UK Department of the Environment.

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