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The paper outlines the current knowledge concerning fate of mycotoxins in the soil environment, including - outline of mycotoxins addressed (trichothecenes, zearalenone, fumonisins, aflatoxins, ochratoxins and patulin) - routes by which the mycotoxins enter the soil environment - routes by which they are immobilised or removed from the soil environment - mycotoxigenic fungi and mycotoxins in the soil environment

Mycotoxins are toxic metabolites formed by specific fungi that grow on living plants and their residues under favourable conditions. They are undesirable ingredients of food and feed. Risks are also posed by the spores and toxin-contaminated raised dusts. Contamination by mycotoxins is a severe problem in food security. More than 300 species of fungi with the ability to form mycotoxins have been identified. More than 400 metabolites are assigned to the group of mycotoxins. Fortunately, only about 20 mycotoxins produced by five genera of fungi (Fusarium, Penicillium, Claviceps, Alternaria and Aspergillus) are found regularly or periodically in food and feed at levels which might have an impact on human and animal health (Gareis, 1999a). Since synthetic fungicides are not allowed in Organic Agriculture, fungal populations are often presumed to be higher in this farming system, and a higher frequency of mycotoxin contamination of organic food and feed has frequently been postulated by Tinker (2001). Others argued that omitting fungicides might lead to higher diversification of microbial populations and therefore limit growth of specific mycotoxin producers. There are controversial reports on varying mycotoxin contamination levels of grains produced organically and in mainstream farming (Marx et al., 1995, Berleth et al., 1998, Birzele et al., 2002, Meier et al., 1999, Stähle et al., 1998, Döll et al., 2002). Thus, the first aim of this contribution is to analyse whether a higher occurence of mould on organically grown crops and, as a result, a higher risk of mycotoxin impact due to specific organic farming as well as low input farming methods is confirmed by the reviewed literature. Secondly, factors that may influence mycotoxin contamination in the different cereal production systems are highlighted. Finally, strategies to reduce mycotoxin contamination are described. The recommendations given are limited to the conditions of the temperate European climate.

A multi-soil study was conducted in Denmark including 29 sites, 8 classified as ‘Organic’, 11 as ‘Conventional with manure and synthetic fertilisers’ and 10 as ‘Conventional with synthetic fertilisers’. The variability of fungal abundance within the three farming systems and the long-term effects of different farming systems on fungal propagules in soil were evaluated. Fungal abundance showed large variations within all three farming systems and this variability reduced the possibility to obtain general conclusions on fungal composition in soils under different farming systems. This was illustrated by the results on total propagule numbers of filamentous fungi and yeasts. Penicillium spp. and Gliocladium roseum were more abundant under organic than conventional farming, while Trichoderma spp. were most abundant in conventionally farmed soils with synthetic fertilisers. These results were not altered after adjusting for possible differences in basic soil properties like total-C and N, extractable P, CEC, base saturation and soil density. The paper discusses whether the differences in fungal abundance are characteristics of a farming system itself or associated with certain management factors being more prevalent in one farming system than the other.

Soil crumbs are important to soil functions. These include plant growth, and the growth of fungi and bacteria forming agents for binding and bonding of new crumbs. We have studied how commercial organic and conventional farming affect this interaction. A diverse crop rotation, including grass, and animal manure resulted in stable crumbs with a high content of biological binding and bonding agents. A cash crop rotation with the addition of only synthetic fertilizers resulted in small, stable aggregates – more like clods - with clay as binding agent. Such a soil will provide poor conditions for preparing seedbeds, because prolonged rain makes it soft and muddy while drought makes it hard as brick.

Jordens krummer er vigtige for vækst. Både vækst af afgrøden og de svampe og bakterier, der laver bindemidler til nye krummer. Vi har undersøgt, hvordan praktisk økologisk og konventionel drift påvirker dette samspil. Et varieret sædskifte med meget græs og husdyrgødning gav gode stabile krummer med højt indhold af biologiske bindemidler. Et ensidigt kornsædskifte med kunstgødning gav i stedet stabile knolde, hvor bindemidlet var ler. Sådan nogle knolde kan give et dårligt såbed, fordi våd jord bliver blød som mudder og tør jord hård som beton.

Aims: To examine if molecular amplified fragment length polymorphism (AFLP) fingerprinting of the only ochratoxin A-producing species in European cereals, Penicillium verrucosum, can be used as a method in hazard analysis using critical control points (HACCP). Methods and Results: A total of 321 isolates of P. verrucosum were isolated from ochratoxin A contaminated cereals from Denmark (oats), UK (wheat and barley) and Sweden (wheat). Of these, 236 produced ochratoxin A as determined by thin layer chromatography; 185 ochratoxin A-producing isolates were selected for AFLP fingerprinting. A total of 138 isolates had unique AFLP patterns, whereas 52 isolates could be allocated to small groups containing from two to four isolates with similar AFLP patterns. A total of 155 clones were found among the 185 P. verrucosum isolates, thus 84 % of the isolates may represent different genets of P. verrucosum. As the few isolates that were grouped often came from the same farm, and those groups that contained AFLP-identical isolates from different countries were morphotypically different. On single farms up to 35 clones were found. The few groups of ramets from the same genet indicated that a HACCP approach based on clones may require a very large number of AFLP analysis to work in practice, we recommend basing the HACCP approach on the actual species P. verrucosum. A more detailed characterization should rather be based on the profile of species present at different control points, or analysis of the mycotoxins ochratoxin A and citrinin in the isolates. Examination of 86 isolates with HPLC and diode array detection of P. verrucosum showed that 66% produced ochratoxin A, 87% produced citrinin, 92% produced verrucin and 100% produced verrucolone. Conclusions: Among 184 ochratoxin A-producing Penicillium verrucosum, 155 clonal lineages were indicated by AFLP fingerprinting, indicating a high genetical diversity, yet the species P. verrucosum is phenotypically distinct and valid. Si

Gennemgang af smitteveje for den ochratoksin dannende svamp P. verrucosum og gode råd om forebyggelse

Soil structure is an important element of soil quality since changes in structural characteristics can cause changes in the ability of soil to fulfil different functions and services. Emphasis in this chapter is placed on the role of soil structure in biological productivity of agroecosystems. Combinations of management practices in which the extent of the degradation of soil structure caused by one practice is balanced or exceeded by the extent of regeneration by other practices will help sustain the productivity of agroecosystems. Tillage and practices that change the organic matter (OM) content of soil are foremost among the many practices that influence soil structure. The links between management, OM content and soil structure and between tillage and soil structure are explored. The feasibility of defining management thresholds or soil quality indicator thresholds with respect to soil structure is assessed.

The positive effects on soil tilth from cropping and fertilisation are prone to destructive forces from traffic and tillage. This presentation provides results from a project aiming to quantify the relative importance of crop rotation, fertilisation and traffic/tillage and their interactions. The investigation includes a field trial established 1986 on loamy sand and another initiated 1997 on a sandy loam. All 1986-trial plots are grown with annual cash crops. Annual incorporation of animal slurry and straw residues is compared to reference plots receiving no organic matter. In the 1997-trial, a diversified crop rotation including grass ley and catch crops is compared to a sequence of annual cash crops excluding catch crops. The latter treatment is performed with and without annual application of animal slurry. In both trials, half of all plots were mechanically compacted by tractor the year prior to investigation. The 1986-trial also included part-plots intensively tilled with a rotary cultivator. Results obtained so far in the 1997-trial indicate that soil organic carbon, microbial biomass, hyphal lengths and soil pore volume are significantly increased by manure application but especially by the diverse crop rotation. In contrast, clay dispersibility and wet aggregate stability were not significantly affected. Hence, biological soil attributes may serve as early indicators of soil quality changes. In the 1986-trial, significant effects of the organic matter treatment were apparent for some biological (microbial biomass), chemical (total and hot-water extractable organic C) and physical (bulk soil strength and friability) attributes. The mechanical disturbance by compaction as well as by intensive tillage caused a significant reduction in soil friability though partly alleviated by the organic matter-treatment.

The industrialization of agriculture and the concurrent increase in societal concerns on environmental protection and food quality have put focus on agricultural management and its impact on soil quality. Soil quality involves the ability of the soil to maintain an appropriate productivity, while simultaneously reducing the effect on the environment and contributing to human health. This development has changed society’s expectations to science and there is an urgent need to improve the communication among researchers from different scientific disciplines. The interaction of scientists with decision-makers is a topic of utmost relevance for future developments in agriculture. Reflexive objectivity denotes the exercise of raising one’s consciousness of the cognitive context, i.e. societal priorities and the values and goals of the researcher. The term sustainability comprehends the priorities in the cognitive context and thus constitutes a valuable tool for expressing the basis of scientific work. Soil quality evaluations should include awareness of the stability of any given quality attribute to disturbance and stress. This implies addressing resistance and resilience of the soil functions and/or the physical form in question. Most existing literature on soil quality focuses on assessment of soil quality rather than the management tools available to influence soil quality. Identification of management thresholds rather than soil quality indicator thresholds is suggested as an important means of implementing the soil quality concept. The major challenges facing modern agriculture include proper nutrient cycling, maintained functions and diversity of soil, protection of an appropriate physical form, and avoidance of chemical contamination. It is suggested that these challenges and problems as related to the soil quality concept are discussed in the framework expounded above.

The availability of nitrogen to crop plants is a universally important aspect of soil quality, and often nitrogen represents the immediate limitation to crop productivity in modern agriculture. Nitrogen is decisive for the nutritive value of plant products and plays a key role in the environmental impact of agricultural production. The fundamental doctrine of nitrogen management is to optimise the nitrogen use efficiency of both introduced and native soil nitrogen by increasing the temporal and the spatial coincidence between availability and root uptake of mineral nitrogen. Natural ecosystems have evolved to produce a high degree of coincidence and maintain a relatively tight nitrogen cycle. The management needed to assure the vitality of crop cultivars with a high production potential cause agroecosystems to be relatively open with respect to nitrogen. By shifting the focus from sheer productivity to a balance between productivity, product quality and environmental impact, the management of agroecosystems can be redesigned to allow for a higher nitrogen use efficiency. The important management measures to improve the nitrogen aspect of soil quality are crop sequences that incorporate cover crops, judicious use of soil tillage, improved timing and use of animal manures, crop residues and mineral fertilizers, and a sustainable balance between plant production potential and animal stocking density. This chapter addresses the characteristics of nitrogen cycling in plant production, the premises upon which an improved nitrogen use has to be based, and discusses management principles that can improve nitrogen use in cropping systems.

Subsoil compaction affects all aspects of soil quality, and contrary to topsoil compaction it is persistent. Natural alleviation processes such as wetting/drying, freezing/thawing and biological activity including root growth decrease rapidly with depth. In compacted soil, these alleviation processes are moreover diminished because root growth and biological activity are reduced and soil water contents remain higher in compacted than in well-structured soil. Wheel loads are still increasing and, in consequence, the extent and severity of subsoil compaction. Sustainable soil management requires the uncompromising criterion that no subsoil compaction can be accepted. Consequently, only field traffic with wheel loads lower than the carrying capacity of the subsoil is allowed. This implies that subsoil stress caused by wheel load should not exceed the strength of the subsoil. Therefore, this chapter emphasises the importance of soil strength and the calculation of soil stresses in the subsoil. One of the main constraints in using the carrying capacity concept proves to be the lack of data on soil strength. Existing recommended limits for wheel loads and inflation pressures are not adequate and can result in over or underestimating of allowable wheel loads and subsequent uneconomical solutions or subsoil compaction. Adequate drainage of soils is a prerequisite for reduced subsoil compaction. Mouldboard ploughing with all tractor wheels on the non-ploughed ‘land’ and umbilical systems for applying manure slurry are realistic options to reduce compaction. Controlled traffic systems that limit the wheeled area may be implemented by the use of wide span vehicles and by steering tractors along traffic lanes. Although we support such provisions, our chapter will advocate and focus primarily on adjusting wheel loads to the carrying capacity of the subsoils.

Ensidige sædskifter uden brug af husdyrgødning har vist sig at udpine jorden så meget, at der (bl.a.) bliver problemer med jordens evne til at smuldre under bearbejdning. Økologiske sædskifter vil oftest være så alsidige, at man dér vil opretholde en passende pulje af nydannet, ’aktivt’ organisk stof. Tildeling af husdyrgødning trækker i samme retning. Mekanisk påvirkning af jorden kan eliminere eller i hvert fald reducere de gode effekter af sædskiftet. Der er derfor al mulig grund til at begrænse skadelig pakning af overjorden mest muligt (brug brede lavtryksdæk) samt – om muligt – at undgå brugen af fræser og rotorharver.

Dårlig kornhåndtering kan føre til dannelse af mykotoksiner under tørring og lagring. De vigtigste toksiner på dansk korn er ochratoksin A (OTA), der dannes af Penicillium verrucosum, og trichothecener og zearalenon, der dannes af Fusarium arter. Fusarium toksiner dannes mest i marken mens OTA dannes på lager. I indlægget vil jeg koncentrere mig om OTA.

Presentation of project PREMYTOX and some of its results at the "Night of Culture" 2004

Soil quality is a concept that allows soil functions to be related to specific purposes. Previous books on soil quality have emphasized descriptive aspects, by focusing on e.g. soil quality indicators, indexing, and minimum data sets. This book takes a management oriented approach by identifying key issues in soil quality and management options to enhance the sustainability of modern agriculture. Topics covered include major plant nutrients (N, P, K), soil acidity, soil organic matter, soil biodiversity, soil compaction, erosion, pesticides and urban waste. Also included are in-depth treatments of the soil quality concept, its history, and its applicability in research and in developed and developing societies. The book will be of significant interest to post-graduate students and researchers in agronomy and in soil, crop and environmental sciences, and to stakeholders involved in issues related to land use and agricultural development.

The susceptibility of spelt to ochratoxin A producing fungi has been investigated.

Ligesom der findes vandkvalitet, luftkvalitet og fødevarekvalitet, findes der jordkvalitet. Og jordens kvalitet hænger nøje sammen med dens struktur, f.eks. dens indhold af partikler og porer. Dette kapitel handler om, hvordan økologisk og konventionelt landbrug påvirker jordkvaliteten. På nogle områder er økologisk landbrug bedst, men ikke på alle.

Når jordbundens mikroorganismer og smådyr har det godt, er jorden som regel også god at dyrke planter i. Og jordbundens levende organismer trives, hvis de får rigeligt med næring og fred og ro. Det første kan økologiske jorde levere, men på grund af mekanisk ukrudtsbehandling ofte ikke det sidste. En mindre del af de konventionelt dyrkede marker giver jordbundsorganismer lige så gode betingelser, så økologisk dyrkning er ikke en absolut betingelse for et godt jordliv.