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GO-GRASS demonstration results show the importance of supportive business environments that foster innovative, grass-based business. The four business cases havethe potential to deliver improved policies for rural development and rural jobs. The White Paper shows that readiness level of some of these initiatives is above technologyreadiness level (TRL) 7 and that significant market breakthrough requires adequate funding, rules and regulations that do not hinder opportunities, and mechanisms thatvalorise additional benefits such as carbon sequestration.Policy makers can stimulate grassland valorisation and foster new opportunities for farmers and rural businesses by securing grasslands functions as a sustainable sourceof raw materials, a space for social, organisation and business innovations, and an important contributor to carbon removal and climate change mitigation.

In this report an inventory is made about which existing and novel technologies are suitable for manure processing on the farm. This includes new stable concepts, to better valorize the manure streams and to see where issues arise. Each technique has a brief description, the quality of the in- and output of the manure is accessed and the potential of the technique on the farm is researched. Formulated is which techniques, or which combination of techniques has a future in the valorization of manure products from new stable concepts, and where more research is necessary to obtain the features or parameters of the systems., In deze rapportage is geïnventariseerd welke bestaande en nieuwe technologieën gebruikt kunnen worden voor de mestbewerking op de boerderij, ook bij nieuwe stalconcepten, om de meststromen beter te verwaarden en welke knelpunten daarbij optreden. Technieken zijn beschreven, de benodigde kwaliteit van de meststroom is bepaald en de potentie voor toepasbaarheid op boerderijschaal is onderzocht. Geformuleerd is welke technieken of welke combinatie van technieken toekomst zouden kunnen hebben voor een betere verwaarding van mestproducten bij nieuwe stalconcepten en waar nader onderzoek naar kenmerken en parameters gewenst is.

This document gives a short overview of the current (national and EU) legislation (as on December 2022) on the bioconversion of several organic streams by insect larvae and compost worms. Legislation concerns different substrates, the status of the invertebrates themselves and the status of the resulting insect frass and vermicompost. Dutch and EU legislation on the production of insect larvae as feed for farmed and pet animals has been developed and adapted in recent years, for example the allowance of different feed products from designated insect larvae species as fish, poultry and pig feed. The legislation is still in development. Recommendations are given.

Black soldier fly larvae (BSFL) are considered a commercially viable solution for global organic waste problems. The objective of this study was to assess the feasibility of rearing BSFL on a wide range of low-value waste streams and its potential to transform them into high-quality animal feed and fertilizer. Six waste streams of different origins were selected and each tested in triplicate. Several parameters were analysed: growth performance, waste reduction index (WRI), conversion efficiency (ECI) and larval composition. Frass composition was also analysed. Larvae reared on fast food waste (FFW) had the highest ECI and WRI and the lowest values when reared on pig manure slurry mixed with silage grass (PMLSG) and slaughter waste (SW). The highest protein content was found for larvae reared on mushroom stems (MS) although this substrate had the lowest protein content. Moreover, the frass nutritional profile was proportionally related to the substrate’s nutritional profile: the protein-rich substrate (SW) resulted in protein-rich frass and the low-protein substrate (MS) resulted in protein-poor frass. The same was true for the lipid content. In conclusion, this study showed that BSFL can be successfully reared on a wide range of waste streams that can affect the larval and frass chemical compositions.

Vermicomposts are earthworm faeces after processing of different organic wastes. The composition is variable and dependent on the nature of the substrate. Several characteristics make vermicomposts interesting for agriculture (plant growth/health, soil health) such as their macronutrient content (N, P, K, organic matter) and specific components (humic acids, phytohormones, enzymes). This literature overview describes multiple researches on the effects of vermicompost in agriculture with a focus on macronutrient content and plant growth.

Black soldier fly (BSF) frass, resulting after bioconversion of organic materials by Hermetia illucens larvae can be used as fertilizer. This overview provides a literature summary of the main (macronutrient) components in frass and its reported effects on plant growth/health and soil. Frass composition is highly dependent on the substrate. Based on average composition, BSF frasses show resemblances to cow manure (C/N ratio, N content), pig slurry (P content), poultry manure (DM, Kcontent) and compost (DM). The frass has a higher organic matter content than compost and beforementioned manure types. Frass seems to be a fast acting fertilizer. Most of the nitrogen is organic,but ammonia content is highly variable. Reported effects on plant growth were often positive or neutra lbut also sometimes negative compared to organic and mineral control fertilizers and there seem to be maximum application rates above which positive effects diminish. Several authors mention that post-treatment of frass (for example by aerobic composting) is necessary to obtain a stable/mature product.Usually the frass is relatively high in P content, which may require extra N fertilizer addition. Severa lauthors state that chitin in the BSF frass likely benefits resistance to plant pathogens. Finally, adding frass can induce changes in the microbial community of the soil/plant rhizosphere. BSF frass can be used as a circular fertilizer in agriculture.

In an experiment described by Elissen et al. (2019) on anaerobic digestion of black soldierfly (BSF, Hermetia illucens) larvae frass, the frass had been previously hygienised due to Dutch law. However, when the frass would stay on the same premises this hygienisation step may not be necessary. A synergistic effect of mixing insect frass with cattle slurry would provide a more positive business case for the insect farmer, since the frass becomes an interesting co-substrate for digesters, resulting in lower disposal costs or even benefits. To determine this synergistic effect, three substrates were tested in lab-scale mesophilic anaerobic digestion tests: Insect frass of BSF larvae grown on agricultural side-streams, either hygienised at 60 °C for 24h or non hygienised and cattle slurry. Also combinations of cattle slurry with insect frass were tested. Biogas production was determined by measuring gas pressure and analysing gas composition. No synergistic effect of adding insect frass to cattle slurry was found in this experiment, and neither differences between hygienised and non hygienised insect frass were found. In other words, adding insect frass to a cattle slurry digester will not lead to an increase in biogas production different from that expected based on adding up biogas productions of the single substrates. However, the partial replacement of cattle slurry with insect frass will increase the amount of biogas produced per digester volume with a factor 3.5 to 9 for respectively 10 % and 30 % replacement. Therefore, it is still interesting to add insect frass to a cattle slurry digester.

Binnen de PPS Biobased opwaarderen van mest en digestaat is een eerste verkenning gedaan naar de economische haalbaarheid van een frass (insectenmest) vergister op het eigen terrein van een BSF (black soldier fly) larven producent. Er is uitgegaan van mono-mestvergisting met een gecombineerde warmte en energie opwekking via een WKK. Door deze opwek hoeft er minder aardgas en elektrain gekocht te worden. Deze winst wordt toegeschreven aan de installatie en heeft met de gebruikte waarden in dit model een terugverdientijd van 10.8 jaar, een installatie heeft normaliter een afschrijftermijn van 20 jaar, hierdoor wordt er iets meer dan 9 jaar winst gemaakt. De winst kan oplopen tot bijna €55.000 euro per jaar, zonder gebruikmaking van subsidies. Echter zijn een aantal gebruikte waarden nog onzeker en is het verstandig dit nader te onderzoeken.

This report describes five experiments to observe the growth of Dendrobaena veneta and Eisenia fetida on substrates originating from Avebe (potato starch and protein producer), Holland Malt (maltings) or others ( kitchen and garden wastes). The substrates include Tarra (Avebe), Secondary food industry Sludge (Holland Malt and Avebe), Barley Dust (Holland Malt), Germinated Barley (Holland Malt), Bokashi (Jansen Wijhe), Potato Peels (van Vulpen voeders), vegetable fruit and garden waste (van der Wal and Ogar), Apple pulp (van Vulpen voeders), Champost (Koolen champignons CNN) and Carrot and Pumpkin Peels (van Vulpen voeders). The compost worms’ growth was monitored for 4-6 weeks. The compost worms were able to convert the substrates into dry, light and powdery vermicompost high in nutrients and organic matter. The compost worms themselves increased in biomass and produced eggs. The protein content of the compost worms ranged between 57.1 and 68.3 % of DM, whereas the fat content ranged between 7.8 and 9.1% of DM. Tarra and Secondary food industry Sludge (Avebe) are suitable substrates for vermicomposting, when mixed with other substrates. Germinated Barley and Secondary Food Industry Sludge (Holland Malt) are less suitable for vermicomposting, due to substrate instability, even when mixed with other substrates. Additions of barley dust and chalk make the substrates’ texture and composition more suitable for the worms to feed on.

BSF larvae are highly efficient in converting all kinds of waste streams into larval protein richbiomass and organic matter. These properties make the BSF larvae perfect candidates for upgrading local waste streams into organic fertilizer in the pilot project ‘Kringlooplandbouw Veenkoloniën’ (circular agriculture Veenkoloniën). In this report different regional substrates, such as germinated barley, barley dust, secondary food industry sludge, primary sludge, pig manure solids, or combinations of these, were used to grow BSF larvae. The growth of the larvae was closely monitored. At the end of the 7 day experiment, the dry matter of the larvae, the growth rate per day, the conversion rate of the substrate and the ease of separating the frass from the larvae were determined. The BSF larvae grew on each substrate, but the highest growth rate (fresh weight) was observed when the larvae were grown on the substrate of germinated barley + barley dust. The observed growth rate was 10.0 mg/day of fresh weight respectively. The highest substrate conversion index (WRI) based on dry matter of 11.93 g/d was observed in primary sludge + germinated barley. Overall, these regional substrates show potential as a feed stream for the cultivation of BSF larvae.

This report starts with a literature review on the topic. From literature it is known that fungi can selectively digest lignin, thereby releasing other components which may subsequently be easily converted into biogas during anaerobic digestion of normally recalcitrant compounds. In addition, several authors have found that commercial fungi can be grown on alternative substrates such as digestates. Four substrates (flax shives, solid fractions of ACRRES digestate, Greendal digestate and cow manure) were incubated with 10 fungi species (Coprinus comatus, Ceriporiopsis subvermispora, Pleurotus ostreatus, Pleurotus eryngii, Lentinula edodes, Hypholoma frowardii, Clitocyba dusenii, Bjerkandera adusta, Hypholoma fasciculare, Gymnopilus sapineus and Kuehneromyces mutabilis). Most combinations of substrates and fungi resulted in growth/colonization, except for all combinations with Greendal digestate, probably due to fungicidal compounds. The most successful combinations were those with P. eryngii, P. ostreatusand G. lucidumon ACRRES digestate, flax shives and cow manure, based on visual signs of fungal colonisation (air mycelium). In general, (average) biogas productions from the different substrates with or without fungal pre-treatmentdid not vary to a large extent and were relatively low (35-73 nm3biogas per ton product). Although in some graphs a slight positive effect on biogas treatment seemed to be taking place, statistical analysis showed that treatment of cow manure with P. ostreatus,P. eryngiiand G. lucidumdid not significantlyincrease the amount of biogas that could be collected. Fungal pretreatment of flax shives also did not lead to increased biogas production with P. eryngiiand G. lucidumand even to a significantly lower biogas production with P. ostreatus.

The goal of this research was to examine the prospects for humic acid products and in particular a humic acid product produced from animal manure/digestate. Based on a literature review it is concluded that humic acids are used worldwide as biostimulants and overall positive effects on crop growth are reported, but variation in results is high. Stakeholders explained during interviews that in the Netherlands the use of Humic acid products are mostly related to niche markets. For conventional agriculture in the Netherland the value of humic acids has not been proven yet, this can be explained by the high fertility of the Dutch soils, and high yields that are already obtained without adding humic acids. Also field experiments were done. In several field experiments with potatoes and onions the specific humic acid product was tested. Adding the humic acids (on soil and as foliar spraying) did not benefit crop growth, but also did not harm the crops. No effect was found on the development of diseases.

For mushroom production usually a mixture of horse and chicken manure and straw is used. For every kg of mushrooms, 5 kgs of waste is produced, a total of 800.000 tonnes per year in the Netherlands. Processing options are often either costly or complex. As the champost contains high salt concentrations, washing results in a solid (less salty) fraction with better re-use options and a nutrient-rich liquid fraction. On the latter fraction growth of five species of commercially relevant micro algae was tested in small-scale well tests. In addition, the press water was also treated with H2O2/UV to reduce the brown colour of the solution. In the majority of the triplicate well tests, growth of three of the five common saltwater algae species (Nannochloropsis gaditana, Porphyridium purpureum, and Tetraselmis chuii) on press water fractions of spent mushroom waste (champost) was found to be comparable to or better than their growth on control media. Dunaliella salina growth was relatively low. Arthrospira platensis only grew on press water when treated with H2O2. Overall, the results indicate that washing of champost results in a mineral rich solution suitable for growth of several (saltwater) algae.

In literature, the synergistic effect of several substrates on feedstocks for anaerobic digestion/methane production is described for several substrates. Champost from mushroom production, vermicompost from worm composting/vermiculture and BSF (black soldier fly) larvae frass from insect production were therefore tested for this report for their synergistic effect. It was found that insect frass had a very high biogas/methane production as a single substrate. Addition of the frass led to a concentration dependent biogas production in mixtures with ‘old’ digestate higher than was expected based on the results of the single substrates. Champost resulted in some biogas production but from vermicompost hardly any biogas could be produced. Also, no synergistic or concentration effects could be noted from the latter two.

This report describes two bioassays for testing disease suppression by BSF frass in an agricultural soil with two crops: sugar beet (Beta vulgaris) and cress (Lepidium sativum). In the bioassay with beet, soil was infected with the plant-pathogenic fungus Rhizoctonia solani while in the bioassay with cress, soil was non-infected or infected with the plant-pathogenic fungus Pythium ultimum. Both concentrations of the BSF frass (7.5 and 15 g/kg soil) proved to be useful as soil application, leading to good plant emergence and growth of sugar beet and cress plants. The highest concentration of BSF frass (15 g/kg soil, both as total product) had a large fertilizer effect. In experiments with cress without addition of Pythium (i.e. with only natural soil infections), disease suppression with BSF frass was found. In all tests, keratin was added as a positive control treatment, which had a higher disease suppression effect than BSF frass but comparable fertilizer effects.

Dit rapport beschrijft groei op en omzetting van de dikke fractie (28 % droge stof) van digestaat door E. fetida wormen (compostwormen) in 6 kweekbedden van elk 5 m2. De begindichtheid van de wormen was 5 kg/m2. Het digestaat was afkomstig uit de ACRRES vergister die gevoed werd met rundermest en natuurgras. In de vijf weken durende proef bij Lumbriculus te Oostwold werd het voorgecomposteerde digestaat continu omgezet in wormencompost waarbij 22 % (natgewicht) van het digestaat afgebroken werd. De omzettingssnelheid was 1.6-3.2 kg (3.2-6.4 L) per kg levende wormen (per m2) per week. Door het opeten van het digestaat veranderden structuur van en nutriënten in het digestaat: De ontstane wormencompost had een korrelige lichte structuur en ammoniak nam bijvoorbeeld met 65 % af. Ook groeiden de wormen in biomassa en produceerden ze cocons. De gemiddelde groei in natte wormenbiomassa was 4 % per week. De maximale snelheden werden nog niet bereikt in dit experiment, maar het is duidelijk dat vermicompostering tot een substantiële afbraak van de dikke fractie van digestaat leidt en de productie van een nieuwe meststof (wormencompost) en nieuw eiwit (wormenbiomassa).

Micro algae's are used as alternative protein source in human and animal diets. Besides micro algae contain substantial amounts of proteins they also contain a high concentration of, often unique, biological and chemical substances with potential to induce beneficial and health promoting effects in humans and animals. This study was set up to evaluate the potential of these substances to improve (intestinal) health. The effect of extracts prepared from 3 monocultures of micro algae's (Chlorella vulgaris [C], Haematococcus pluvialis [H], and Spirulina platensis [S]) and a mixed culture of micro algae's (AM; a mixture of Scenedesmus sp. and Chlorella sp. ) was studied in the presence and absence of the enterotoxigenic bacterium Escherichia coli k99 strain (ETEC, [E]) as an in vitro challenge. The E.coli-k99 strain with adhesion factor F41 (41/32) was isolated from a mastitis-infected udder. Gene expression was measured in cultured intestinal porcine epithelium cells (IPECJ2 cell line) after 2 and 6 hours incubation with C, H, and S extracts, and after 6 hours with the AM extract, using “whole genome” porcine microarrays. Gene expression profiles were analysed using functional bioinformatics programs to provide insight in the biological processes induced by micro algae extracts.

The aim of this study was to describe the challenges faced by the Dutch dairy sector in terms of climate change mitigation and adaptation, and to show possible pathways for implementation of mitigation and adaptation options towards 2030 and 2050. With regard to mitigation, the dairy sector has to comply with targets for mitigation of greenhouse gas emissions in sectoral, national and European legislation. With regard to adaptation, dairy farms are expected to benefit from increasing temperatures and CO2 concentrations, but this may be counteracted by increases in extreme weather events and animal and plant diseases and plagues. A roadmap is shown with phased implementation of mitigation- and adaptation options, based on their effectiveness, costs, readiness for practical implementation, and interaction with other aspects of sustainability., Het doel van deze studie was om in kaart te brengen voor welke opgave de Nederlandse melkveehouderijsector staat met betrekking tot klimaatmitigatie en –adaptatie, en bij te dragen aan oplossingsrichtingen in de vorm van een routekaart voor implementatie van klimaatslimme maatregelen op de korte- en middellange termijn (2030, 2050). Wat betreft mitigatie moet de sector voldoen aan beleidsdoelstellingen voor reductie van broeikasgasemissies in sectoraal, nationaal en Europees beleid. Wat betreft adaptatie wordt enerzijds verwacht dat de melkveehouderij kan profiteren van hogere temperaturen en CO2 concentraties, maar anderzijds kan een toename in weersextremen en dierlijke/plantaardige ziekten en plagen dit effect afzwakken of teniet doen. De routekaart betreft een gefaseerde implementatie van mitigatie- en adaptatiemaatregelen, waarbij rekening wordt gehouden met effectiviteit, kosten, afwentelingen en praktijkrijpheid van maatregelen.

Non-chemical methods for weed control in arable crops are reviewed.

Hoe kunnen veetelers met minder input meer resultaten halen bij snijmaïsteelt? Dat is de centrale vraag van het project “Duurzaam bodembeheer maïs” (BO-31.03-001-003). Veel melkveehouderijbedrijven telen snijmaïs, een gemakkelijk te telen ruwvoergewas met een goede productie van constante hoge kwaliteit. Als zetmeelbron met een ruime energie/eiwitverhouding past het goed in het runderdieet, naast gras en graskuil. De maïsteelt kan echter nadelige effecten hebben voor de bodem door gewasbeschermingsmiddelen en het uit- en afspoelen van nutriënten. Wageningen UR en het Louis Bolk Instituut onderzoeken in opdracht van het ministerie van EZ duurzame en praktisch haalbare verbeteringen en vernieuwingen. Teeltsystemen die zorgen voor een gezonde bodem worden daarbij gezien als sleutel tot duurzame teelt. Op drie locaties worden diverse teeltsystemen vergeleken in meerjarige proeven uitgevoerd op zand- en kleigrond. Daarbij wordt onder andere gekeken naar opbrengst, onkruiddruk, bodemstructuur, aanwezigheid van regenwormen, indringingsweerstand, waterinfiltratie, stikstofdynamiek en economische aspecten. Deze kennis wordt vervolgens doorgegeven aan de praktijk middels o.a. de beslisboom snijmaïs, een instrument om praktische kennis naar veetelers en erfbezoekers te brengen. De resultaten uit het vijfde projectjaar (2016) worden in deze rapportage beschreven. Onderstaande paragrafen geven eerst per proeflocatie een korte samenvatting van de bevindingen van 2016.

Non-chemical weed management covers all management practices that influence weeds except herbicides. This chapter summarises the major achievements in European research, as well as work undertaken in North America. Research groups from both continents have interacted strongly on the topic over the years and shared common interests on the development of non-chemical tactics. The chapter encompasses preventive, cultural and direct weed control methods, explaining the basic principles and the integration of these tactics in weed management strategies for agricultural and horticultural crops and in some cases amenity areas as well. Preventive methods reduce weed germination, cultural methods improve crop competition and direct physical weed control reduces weed survival. Non-chemical weed management is mainly adopted in organic crop production, as conventional growers still perceive it as more costly and less reliable than herbicide-based weed control programmes.

The paper describes the major achievements made in European research regaridng physical methods for weed control in agricultural and horticultural crops