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BACKGROUND: A 2 year study was conducted to evaluate the efficacy of biological control with optimally timed Trichogramma brassicae releases as an integrated pest management tool against the European corn borer (ECB), Ostrinia nubilalis (Hübner), in on-farm experiments (i.e. real field conditions) in three European regions with dissimilar geoclimatic conditions and ECB pressure and conventional management (i.e. insecticide treated and untreated). RESULTS: Biological control with Trichogramma (1) provided ECB protection comparable with conventional management, (2) in all cases maintained mycotoxin levels below the EU threshold for maize raw materials destined for food products, (3) was economically sustainable in southern France and northern Italy, but not in Slovenia where it resulted in a significant decrease in gross margin, mainly owing to the cost of Trichogramma product, and (4) enabled avoidance of detrimental environmental effects of lambda-cyhalothrin use in northern Italy. CONCLUSION: Optimally timed mass release of T. brassicae could be considered a sustainable tool for IPM programmes against ECB in southern France and northern Italy. Better involvement of regional advisory services is needed for the successful dissemination and implementation of biological control. Subsidy schemes could also motivate farmers to adopt this IPM tool and compensate for high costs of Trichogramma product.

Abstract The use of organic soil amendments, such as green manures, animal manures, composts or slurries, certainly has many advantageous aspects for soil quality and is suggested as a promising tool for the management of plant-parasitic nematodes. However, during a recent literature survey we also found numerous studies reporting an increase of plant-parasitic nematodes after the use of organic amendments. Therefore, we critically re-evaluated the usefulness of organic amendments for nematode management and suggest possible mechanisms for a stimulation of plant-parasitic nematodes, as well as mechanisms that might be causing a reduction of plant-parasitic nematodes. In addition, we also elucidate a possible mechanism that might be responsible for the observed overall positive effects of organic amendments on crop yields. It is likely that a significant part of this is, inter alia, due to the proliferation of non-pathogenic, free-living nematodes and their overall positive effects on soil microbial populations, organic matter decomposition, nutrient availability, plant morphology and ecosystem stability.

1,2-dehydropyrrolizidine ester alkaloids (pyrrolizidine alkaloids; PAs) are a class of secondary plant metabolites found in hundreds of plant species. In vitro, PAs are known to affect plant-parasitic nematodes. Thus, PA-producing plants might be used in nematode management. So far, however, Crotalaria is the only PA-producing plant that has been used for nematode control. Consequently, we reviewed the literature on other PA plants and their effects on nematodes. This included the analysis of in vitro experiments with PA plant extracts, host tests with PA plants, as well as experiments in which PA-producing plants were used as different types of soil amendments (mulch, in situ mulching, extracts). Our results clearly show that, in addition to Crotalaria, certain other PA-producing plant species have the potential to be used in sustainable nematode management. This is especially true for management of sedentary endoparasitic nematode species. Promising applications include the use of PA plant extracts and mulches, as well as the use of PA plants for in situ mulching.

The national phosphorus balance can be made more sustainable by reducing the accumulation of phosphorus in agricultural soils and by increasing recycling from waste streams. This study investigated different scenarios for reduction of the national soil surplus on agricultural land. The focus was on scenarios that will not compel agriculture in the Netherlands to change radically e.g. reduction of phosphorus fertilisation levels and reducing animal phosphorus excretion by improving feeding efficiency while maintaining national milk and meat production levels.

The national phosphorus balance can be made more sustainable by reducing the accumulation of phosphorus in agricultural soils and by increasing recycling from waste streams. This study investigated different scenarios for reduction of the national soil surplus on agricultural land. The focus was on scenarios that will not compel agriculture in the Netherlands to change radically e.g. reduction of phosphorus fertilisation levels and reducing animal phosphorus excretion by improving feeding efficiency while maintaining national milk and meat production levels.

Processing of manure intends to increase the use efficiency of nutrients. A concentrated solution of nitrogen (N) and potassium (K) (‘mineral concentrate’) is one of the possible products resulting from manure processing. A study is carried out in the Netherlands to determine the agronomic and environmental effects of the production and use of such mineral concentrates. This concentrate is produced by reverse osmosis of the liquid fraction of separated livestock slurry. On average 92% of the N in mineral concentrate is present as ammonium-N, the other 8% as organic N. Pot experiments with different soils and crops showed that the Nitrogen Fertiliser Replacement Value (NFRV) of mineral concentrate compared to calcium ammonium nitrate (CAN) ranged from 76 – 97%. The NFRV of injected mineral concentrate compared to CAN ranged in the field experiments from 72 – 84% for arable land and 54 – 80% for grassland. NFRV of injected mineral concentrate was similar to that of injected liquid ammonium nitrate. Mineral concentrate is an ammonium (NH4) containing fertiliser with a high pH (about 8). Experiments showed that application of mineral concentrates may result in ammonia (NH3) and nitrous oxide (N2O) emissions. Injection or incorporation of mineral concentrate strongly decreased NH3 emission. The N2O emission from mineral concentrate is probably related to the presence of organic carbon in concentrates and/or high NH3 concentration in the soil. The risk of nitrate leaching from applied mineral concentrates was similar or lower than that from CAN, for both grassland and arable land. Obviously, NH3 emission and denitrification were the dominant N loss pathways after application of mineral concentrate. There is scope to decrease N losses and increase NFRV of mineral concentrate by use of low NH3 emission application techniques, and a further decrease of the organic N content of concentrate. Scenario analyses on national scale showed that large scale use of mineral concentrate and the attending solid fraction in the Netherlands decreased the need for mineral N and P fertilisers up to 15% and 82%, respectively. Moreover, the manure surplus in Netherlands decreases up to 84% and therefore this manure has not to be exported. The total NH3 and N2O emissions and N leaching in the Netherlands hardly changed in the scenarios. Large scale use of mineral concentrate increases the N and P use efficiency on a national scale. Key words: fertiliser, manure, mineral concentrate, nitrogen, potassium, processing, reverse osmosis

Current open field vegetable production systems in The Netherlands do not meet market and society demands. Among the most important demands are: (1) the EU Water Framework Directive, requesting strong reductions in emissions of nutrients and pesticides to surface- and groundwater; (2) continuous delivery of uniform, high quality products by retailers. These demands could not be fulfilled by adapting current production systems, new production systems have to be developed and tested for a number of field grown crops. This paper emphasizes the development of soilless growing systems for leek. Important current product requirements for leek are a white part of the stem of at least 14 cm, a minimal thickness of 2.5 cm and a straight, firm stem. Important system requirements for outdoor cultivation are handling of rainfall, wind and frost. Opportunities for soilless systems for leek are a clean product without soil contamination and a strong reduction in labor need for preparing it for the market. Finally, the developed system needs to be economically viable, acceptable by growers and give sufficient reduction in emissions. From 2008 aspects of plant raising (traditional method with stone wool and coir plugs) were investigated together with demands to get a firm straight stem. Covering of the plants to achieve a long white part was investigated comparing several smart solutions. The use of substrate, NFT and deep flow were also compared. Results show a fast growing crop, where 4 crops per year with at least 80 plants per m2 and a total yield up to 300 t/ha are possible. It can achieve the minimal market weight in a much shorter period (40-60 days in summer) compared to growing in the soil. However, the production of long white stems requires special measures. With a good system design there are hardly any problems with rain and frost.

High qualified strawberry (Fragaria × ananassa) planting material, mainly for export, is produced by Dutch growers on circa 1100 ha field area in The Netherlands. Planting stock must be destroyed if strawberry tarsonemid mite (Phytonemus pallidus) or infection by the plant parasitic nematode Meloidogyne hapla is found by the Dutch Quality Board. Also the nematode Pratylenchus penetrans can attack strawberry plants severely. The presence of tarsonemid mites in plant material can result in a considerable loss of production. Until 2007 in The Netherlands mother planting stock for runner production was treated with methyl bromide (MeBr) to eliminate tarsonemids. This chemical disinfestation method is banned since 2008. From 2007 the choice was made to optimize the Controlled Atmosphere Temperature Treatment (CATT) to provide a non-chemical and sustainable method for future disinfestation. By application of CATT during 48 h at a temperature of 35°C and 50% CO2 mortality of the tarsonemid mites is over 99.8%. No harmful irreversible results of CATT on vitality of mother plants in the field and runner production are found. From 2009 CATT is up scaled to a commercial level and widely applied by Dutch producers of planting stock. As a spin-off also plant parasitic nematodes are reduced by application of CATT. Understanding of the influence of different factors during CATT creates also possibilities for optimization this treatment to control P. penetrans and M. hapla in strawberry plants or in the soil particles attached to the roots. Application of an optimized CATT can prevent further dispersion of these plant parasitic nematodes in the strawberry chain.

Processing of manure intends to increase the use efficiency of nutrients. A concentrated solution of nitrogen (N) and potassium (K) (‘mineral concentrate’) is one of the possible products resulting from manure processing. A study is carried out in the Netherlands to determine the agronomic and environmental effects of the production and use of such mineral concentrates. This concentrate is produced by reverse osmosis of the liquid fraction of separated livestock slurry. On average 92% of the N in mineral concentrate is present as ammonium-N, the other 8% as organic N. Pot experiments with different soils and crops showed that the Nitrogen Fertiliser Replacement Value (NFRV) of mineral concentrate compared to calcium ammonium nitrate (CAN) ranged from 76 – 97%. The NFRV of injected mineral concentrate compared to CAN ranged in the field experiments from 72 – 84% for arable land and 54 – 80% for grassland. NFRV of injected mineral concentrate was similar to that of injected liquid ammonium nitrate. Mineral concentrate is an ammonium (NH4) containing fertiliser with a high pH (about 8). Experiments showed that application of mineral concentrates may result in ammonia (NH3) and nitrous oxide (N2O) emissions. Injection or incorporation of mineral concentrate strongly decreased NH3 emission. The N2O emission from mineral concentrate is probably related to the presence of organic carbon in concentrates and/or high NH3 concentration in the soil. The risk of nitrate leaching from applied mineral concentrates was similar or lower than that from CAN, for both grassland and arable land. Obviously, NH3 emission and denitrification were the dominant N loss pathways after application of mineral concentrate. There is scope to decrease N losses and increase NFRV of mineral concentrate by use of low NH3 emission application techniques, and a further decrease of the organic N content of concentrate. Scenario analyses on national scale showed that large scale use of mineral concentrate and the attending solid fraction in the Netherlands decreased the need for mineral N and P fertilisers up to 15% and 82%, respectively. Moreover, the manure surplus in Netherlands decreases up to 84% and therefore this manure has not to be exported. The total NH3 and N2O emissions and N leaching in the Netherlands hardly changed in the scenarios. Large scale use of mineral concentrate increases the N and P use efficiency on a national scale. Key words: fertiliser, manure, mineral concentrate, nitrogen, potassium, processing, reverse osmosis

M. minor is a recently described nematode (Karssen et al, 2004) that has been found on sport fields, golf courses, and more recently also in potato growing fields in the UK and the Netherlands. A Pest Risk Analyses (PRA) was carried out in 2007, showing a lack of existing information on the damage thresholds on arable crops. Therefore, a project was started in 2008 aimed to resolve this lack of knowledge. Thus, a naturally M. minor-infested field was subjected to a variety of crops (maize, rye, annual ryegrass, potato, sugar beet, black fallow) to asses their host status and, to achieve various initial population densities (Pi) of M. minor in the soil. Subsequently, in spring 2009, two potato cultivars were planted in these plots. From these studies it is obvious that nematode were able to multiply on potatoes whereby reproduction took place within roots as well as potato tubers, respectively. This, of course, increases the risk of spreading this nematode species by seed potatoes. No substantial reproduction was present on other host plants

M. minor is a recently described nematode (Karssen et al, 2004) that has been found on sport fields, golf courses, and more recently also in potato growing fields in the UK and the Netherlands. A Pest Risk Analyses (PRA) was carried out in 2007, showing a lack of existing information on the damage thresholds on arable crops. Therefore, a project was started in 2008 aimed to resolve this lack of knowledge. Thus, a naturally M. minor-infested field was subjected to a variety of crops (maize, rye, annual ryegrass, potato, sugar beet, black fallow) to asses their host status and, to achieve various initial population densities (Pi) of M. minor in the soil. Subsequently, in spring 2009, two potato cultivars were planted in these plots. From these studies it is obvious that nematode were able to multiply on potatoes whereby reproduction took place within roots as well as potato tubers, respectively. This, of course, increases the risk of spreading this nematode species by seed potatoes. No substantial reproduction was present on other host plants

Biological indicators are highly relevant for assessing the condition of a soil as they are integrative; they reflect the overall impact of physical, chemical and biological changes. Indigenous soil organisms are preferable to other test organisms because the diversity and condition of indigenous soil organisms reflect both acute and chronic effects of soil disturbances. Nematodes are ubiquitous, speciose, easily extractable and present in extremely high numbers. Given the ever increasing amount of sequence data, DNA barcode-based community analysis will soon be possible and a next step would be to define objective criteria for the ecological grouping of soil nematodes. Here, we present a framework to ascertain which traits are correlated with a tolerance to stress. For this, a field study on the effects of pH and copper on nematode communities was re-analysed. Changes in abundances of individual genera were correlated with a number of potentially stress tolerance-related characteristics. The generalised least squares (GLS) method was used to account for the phylogenetic dependence of the data. Only the relationship between the ability to enter a survival stage and tolerance to copper at pH 6.1 was found to be significant, but the quantity of missing data probably had a negative impact on the analyses. This study did, however, clearly demonstrate the importance of accounting for the effects of phylogenetic dependence in the data. When the phylogeny was taken into account, we observed an average change in P value of 0.196 (and in some cases as much as 0.6) for the correlations of possible stress-related characteristics and Cu or pH tolerance. This research constitutes a proof-of-principle for a transparent method to relate stress tolerance to (ecological) characteristics. The usefulness of this powerful method should become even clearer when substantially higher numbers of individuals are analysed (as facilitated by using DNA barcodes) and when missing data are filled in

In recent years scientists of Wageningen UR (University & Research centre) dedicated much effort to systems innovations in agriculture and horticulture. Complex and persistent environmental problems require new approaches, new so-called proof of principles that should offer farmers and growers of the future new perspectives in a development course towards more sustainable farm management systems. And this course was – and still is - characterised by intensive cooperation with a large number of stakeholders: farmers and growers and their representatives, businesses in various links of the chain, regional organisations, service industries and knowledge institutions, societal organisations and authorities. This is because development and implementation of sustainable farming requires the development of new techniques as well as – at the same time - acquiring support for the implementation of such changes among all stakeholders. This is why communication and knowledge transfer were playing such an important role in the systems innovation programmes. This report presents the four innovation projects and their results, together with a short description of the embedding of these projects in the future explorations that have been conducted together with stakeholders.

In recent years scientists of Wageningen UR (University & Research centre) dedicated much effort to systems innovations in agriculture and horticulture. Complex and persistent environmental problems require new approaches, new so-called proof of principles that should offer farmers and growers of the future new perspectives in a development course towards more sustainable farm management systems. And this course was – and still is - characterised by intensive cooperation with a large number of stakeholders: farmers and growers and their representatives, businesses in various links of the chain, regional organisations, service industries and knowledge institutions, societal organisations and authorities. This is because development and implementation of sustainable farming requires the development of new techniques as well as – at the same time - acquiring support for the implementation of such changes among all stakeholders. This is why communication and knowledge transfer were playing such an important role in the systems innovation programmes. This report presents the four innovation projects and their results, together with a short description of the embedding of these projects in the future explorations that have been conducted together with stakeholders.

To investigate the possibilities for a more sustainable use of phosphorus it was necessary to have a complete picture of the national phosphorus flows in the Netherlands. In this report a material flow analysis was performed by dividing the national system into a number of subsystems: agricultural subsystems (arable, grazing, intensive livestock) but also non-agricultural subsystems (food industry, non-food industry, feed industry, household, waste management, environment) were included. Quantification of the various phosphorus flows between the subsystems was done for the year 2005 and was based on various data sources. The results showed that in the reference year 2005 a surplus of around 60 Mkg of P existed, roughly half of this amount accumulated in agricultural soil. The remaining part ended up in ground or surface water (around 7 Mkg) or was sequestered in one way or another (e.g. landfill, incineration ashes, sewage sludge etc.). Recycling from society (households and industry) back to agriculture was minimal. Options for a more sustainable use of phosphorus in the Netherlands are discussed.

Biological soil disinfestation is an environmentally friendly method to disinfest soil. From now on we refer to it as anaerobic soil disinfestation (ASD). With ASD a green manure crop (40 t/ha) is homogeneously incorporated into the topsoil (0-30 cm) after which the field is lightly compacted and irrigated. Subsequently the field is mechanically covered with air tight virtually impermeable film (VIF) to restrict oxygen supply to the topsoil. The soil is left covered for six weeks in the summer. In this period anaerobic conditions develop rapidly in which toxic fermentation products are formed. These conditions are responsible for elimination of fungal and bacterial pathogens as well as parasitic nematodes, insects and weeds. In the Netherlands since 2004 anaerobic soil disinfestation (ASD) was applied on approximately 70 ha mainly for asparagus and strawberry runners production. When the asparagus crop was replanted ASD proved to be profitable for many years by controlling Fusarium oxysporum. Although highly effective against soilborne pathogens and pests ASD is not applied widely in the Netherlands due to the high costs of about € 4000 per ha. Apart from the costs this technique needs special attention to prevent plastic damage. Moreover the mechanism behind ASD is not well defined which makes recommendations for growers complex. A new and promising development in ASD is the application of defined products on a basis of mixtures of carbon hydrates and proteins. The mechanism of ASD will be studied in the next few years with some of these products by measuring gases and fatty acids and microbial shifts in relation to efficacy. Chemical soil disinfestation with fumigants is restricted more and more and a non-chemical approach of soil disinfestation like ASD is urgently needed

Pseudomonas syringae pv. porri, the causal agent of bacterial blight of leek, is a current threat for leek (Allium porrum) production in the Netherlands. The roles of post-harvest crop waste and plant invasion from soil in leek plant infection was investigated with the purpose to gain better understanding on the ecology and epidemiology of this pathogen. In a survey done over 167 leek fields, P. syringae pv. porri was present in 101 fields. About a tenfold higher P. syringae pv. porri average infection rate was recorded in leek plants from fields where post-harvest crop waste was returned than in those from fields where no waste was returned. P. syringae pv. porri could survive for at least 1 month in shredded plant material made from infected plants (mimicking crop waste in practice). Field experiments done over three successive years revealed that leek plants that were treated with crop waste at the nursery and production growth stages consistently showed higher infection rates than plants that remained untreated. Plants that were treated with crop waste only at one of both stages revealed intermediate infection rates. In a plant-soil microcosm study, it appeared that P. syringae pv. porri strain P55R colony numbers in the leek rhizosphere were approximately 4 orders in magnitude higher than in corresponding bulk soils. P. syringae pv. porri was shown to colonize leek roots and cells of the pathogen were also present in the leaves. It was concluded that post-harvest crop waste play an important role in the epidemiology of P. syringae pv. porri in leek production. The following route for primary infection of leek plants is proposed, from crop plant residues via soil to leek roots and plants. (C) 2010 Elsevier B.V. All rights reserved.

To investigate the possibilities for a more sustainable use of phosphorus it was necessary to have a complete picture of the national phosphorus flows in the Netherlands. In this report a material flow analysis was performed by dividing the national system into a number of subsystems: agricultural subsystems (arable, grazing, intensive livestock) but also non-agricultural subsystems (food industry, non-food industry, feed industry, household, waste management, environment) were included. Quantification of the various phosphorus flows between the subsystems was done for the year 2005 and was based on various data sources. The results showed that in the reference year 2005 a surplus of around 60 Mkg of P existed, roughly half of this amount accumulated in agricultural soil. The remaining part ended up in ground or surface water (around 7 Mkg) or was sequestered in one way or another (e.g. landfill, incineration ashes, sewage sludge etc.). Recycling from society (households and industry) back to agriculture was minimal. Options for a more sustainable use of phosphorus in the Netherlands are discussed.