Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Post-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate
Prats, Sergio A. ; González-Pelayo, Óscar ; Silva, Flavio C. ; Bokhorst, Koen J. ; Baartman, Jantiene E.M. ; Keizer, Jan J. - \ 2019
Earth Surface Processes and Landforms 44 (2019)14. - ISSN 0197-9337 - p. 2837 - 2848.
effectiveness - erosion - mulch - organic matter - wildfire

Mulching with forest residues has proved to be highly effective in reducing post-fire soil losses at the plot scale. However, its effectiveness has not been quantified at the application rates that are typically used in operational post-fire land management (2–3 Mg ha-1 using straw), as well as at scales larger than 100 m2. The present study compared post-fire erosion rates for six convergent hillslopes or swales of 500 to 800 m2, three of which were left untreated while the other three were mulched immediately after the fire with shredded eucalypt bark at a rate of 2.4 Mg ha-1. Erosion rates were monitored at irregular intervals during the first three post-fire years, whilst ground cover was assessed yearly. Selected topsoil properties (0–2 cm) such as organic matter content and aggregate stability were determined at a single occasion – two years after the wildfire, for three micro-environments separately: bare soil, and under mulch/litter and vegetation. Soil losses on the untreated swales decreased with post-fire year from 2.2 to 0.4 and 0.11 Mg ha-1 yr-1 (respectively for the first, second and third post-fire years), while the mulched swales produced 84%, 77% and 38% less soil losses than the untreated swales. Soil losses also depended on slope aspect, with the north-facing swales producing less erosion than the west-facing ones. This could be linked to their significant differences in bare soil, vegetation and stone cover, or a combination thereof. The type of micro-environment also played a significant role in topsoil properties (stone content, bulk density, resistance to penetration/shear stress, porosity and organic matter content). The present results add to the increasing evidence that forest residues should be duly considered for operational post-fire land management. Forest residues were highly effective in reducing erosion from swales at application rates as low as the typical 2 Mg ha-1 of post-fire straw mulch.

Recycling nutrients contained in human excreta to agriculture: Pathways, processes, and products
Harder, Robin ; Wielemaker, Rosanne ; Larsen, Tove A. ; Zeeman, Grietje ; Öberg, Gunilla - \ 2019
Critical Reviews in Environmental Science and Technology 49 (2019)8. - ISSN 1064-3389 - p. 695 - 743.
blackwater - carbon - feces - fertilizer - nitrogen - organic matter - Phosphorus - potassium - recovery - resource-oriented sanitation - sewage - soil amendment - source-separation - urine - wastewater

The need for better nutrient management has spurred efforts towards more comprehensive recycling of nutrients contained in human excreta to agriculture. Research in this direction has intensified throughout the past years, continuously unfolding new knowledge and technologies. The present review aspires to provide a systematic synthesis of the field by providing an accessible overview of terminology, recovery pathways and treatment options, and products rendered by treatment. Our synthesis suggests that, rather than focusing on a specific recovery pathway or product and on a limited set of nutrients, there is scope for exploring how to maximize nutrient recovery by combining individual pathways and products and including a broader range of nutrients. To this end, finding ways to more effectively share and consolidate knowledge and information on recovery pathways and products would be beneficial. The present review aims to provide a template that aims to facilitate designing human excreta management for maximum nutrient recovery, and that can serve as foundation for organizing and categorizing information for more effective sharing and consolidation.

On the role of soil organic matter for crop production in European arable farming
Hijbeek, Renske - \ 2017
Wageningen University. Promotor(en): M.K. van Ittersum, co-promotor(en): H.F.M. ten Berge. - Wageningen : Wageningen University - ISBN 9789463436632 - 211
soil fertility - soil fertility management - soil management - soil conservation - organic matter - soil organic matter - nitrogen - nitrogen fertilizers - green manures - manures - straw - soil carbon sequestration - cover crops - crop yield - yields - meta-analysis - food security - europe - drivers - barriers - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - bodembeheer - bodembescherming - organische stof - organisch bodemmateriaal - stikstof - stikstofmeststoffen - groenbemesters - mest - stro - koolstofvastlegging in de bodem - dekgewassen - gewasopbrengst - opbrengsten - meta-analyse - voedselzekerheid - europa - chauffeurs - barrières

The aim of this thesis was to improve understanding of the role of organic inputs and soil organic matter (SOM) for crop production in contemporary arable farming in Europe. For this purpose, long-term experiments were analysed on the additional yield effect of organic inputs and savings in mineral fertiliser. In addition, a farm survey was conducted to find drivers and barriers for the use of organic inputs and to assess if arable farmers in Europe perceive a deficiency of SOM.

The findings in this thesis suggest that at least on the shorter term, on average, there seems to be no immediate threat from a deficiency of SOM to crop production in arable farming in Europe. The long-term experiments showed that with sufficient use of only mineral fertilisers, on average, similar yields could be attained over multiple years as with the combined use of organic inputs and mineral fertiliser. This was reflected in the farm survey, in which a large majority of farmers indicated not to perceive a deficiency of SOM. Analysis of long-term experiments also showed that more mineral fertiliser N was saved when using farmyard manure at high N rates (with mineral fertiliser application) than at low N rates (without mineral fertiliser application), based on comparisons at equal yield.

Specific crops and environments did benefit from organic inputs and more SOM in terms of crop production. Long-term experiments showed that organic inputs give benefit to crop production in wet climates and on sandy soils. In addition, farmers perceived a higher deficiency of SOM on steep slopes, sandy soils, wet and very dry climates. The additional yield effect of organic inputs was significant for potatoes. More in general, farmers who cultivated larger shares of their land with specialized crops (including potatoes, sugar beets, onions and other vegetables) than cereals perceived a higher deficiency of SOM. It seems that while the functions of SOM can be replaced with technical means to a large extent (e.g. tillage, use of mineral fertilisers), there are limits to this technical potential when environmental conditions are more extreme and crops are more demanding.

The farm survey revealed that farmers perceive a trade-off between improved soil quality on the one hand and increased pressures from weeds, pests and diseases and financial consequences on the other hand when using organic inputs. If policies aim to stimulate the maintenance or increase of SOM, more insight is needed into the conditions that regulate the pressures of weeds, pests and diseases in response to organic inputs. Financial consequences (at least on the short term) should also be accounted for. More importantly however, benefits from SOM for crop production cannot be taken for granted. Only in specific situations such benefits will exist. If European policies on SOM aim to include benefits for crop production, focus should be on areas with more extreme environmental conditions (very dry or wet climates, steep slopes, sandy soils), or cropping systems with more specialized or horticultural crops rather than cereals.

De bodem onder ons bestaan: interview met prof.dr. Lijbert Brussaard over de biologie van de bodem
Brussaard, Lijbert - \ 2017
mycorrhizal fungi - cropping systems - organic farming - minerals - fertilizer application - green manures - organic matter - soil biology - mycorrhizas
Ecophysiology of sulfate-reducing bacteria and syntrophic communities in marine anoxic sediments
Özüölmez, Deya - \ 2017
Wageningen University. Promotor(en): A.J.M. Stams; Caroline M. Plugge. - Wageningen : Wageningen University - ISBN 9789463436540 - 225
degradation - marine sediments - methanobacteria - microorganisms - organic matter - anoxia - sulfate reduction - degradatie - mariene sedimenten - methanobacteria - micro-organismen - organische stof - anoxie - sulfaatreductie

Propionate, butyrate, acetate, hydrogen and formate are the major intermediates of organic matter degradation. Sulfate-reducing bacteria (SRB) contribute significantly to the consumption of these substrates in sulfate-rich marine sediments. In sulfate-depleted sediments, however, complete degradation of propionate or butyrate is only possible via syntrophic cooperation of acetogenic bacteria and methanogenic archaea. Despite that the predominance of SRB in sulfate-rich and methanogens in sulfate-depleted sediments was reported, recent studies showed that both types of microorganism could be present in upper and lower parts of marine sediments. In this thesis, propionate and butyrate conversions and the involved microbial community in sulfate, sulfate-methane transition and methane zone sediment of Aarhus Bay, Denmark were studied using sediment slurry incubations. Interspecies hydrogen transfer and coexistence during acetate degradation were investigated in mixed pure cultures.

In Chapter 2, interspecies hydrogen transfer between aceticlastic Methanosaeta concilii and hydrogenotrophic microorganisms, Desulfovibrio vulgaris or Methanococcus maripaludis, was investigated. Additionally, coexistence of M. concilii and Desulfobacter latus growing on acetate under sulfidogenic conditions was studied. The results of Chapter 2 showed that D. vulgaris could reduce sulfate and grow on leaked hydrogen from M. concilii. Hydrogen leakage from M. concilii provides an explanation for biogeochemical zonation both for competitive (e.g. acetate) and non-competitive substrates (methyl compounds), and this indicates the possible coexistence of SRB and methanogens in sulfate-rich environments.

In chapter 3 and 4, long term incubations were examined focusing on butyrate and propionate conversion and the microbial community dynamics in sediment slurry enrichments at different sulfate (o, 3 and 20 mM) concentrations and incubation temperatures (10°C and 25°C). Sulfate reduction is the dominant process for butyrate and propionate conversion in Aarhus Bay sediments. In the absence of sulfate, both substrates can be converted efficiently, indicating the presence of syntrophic communities throughout the sediment. The fluctuating methane concentrations and the enrichment of anaerobic methanotrophic archaea (ANME) during butyrate and propionate conversion at 10°C suggest the occurrence of anaerobic oxidation of methane (AOM) in sulfate-methane transition zone (SMTZ) of Aarhus Bay.

The microbial community involved in butyrate and propionate conversions were investigated using next generation sequencing (NGS) of the 16S rRNA amplicon sequencing. The enriched sulfate-reducing bacteria at high sulfate concentration (20 mM) were different when butyrate and propionate were used as substrate. Desulfosarcina and Desulfobacterium dominate the butyrate-converting slurries (Chapter 3), whereas Desulfosarcina, Desulfobulbus and Desulforhopalus are the main SRB in propionate-converting slurries (Chapter 4). The increase in the relative abundance of Desulfobacteraceae and Desulfobulbaceae in SZ, SMTZ and MZ sediment slurries suggests the presence of sulfate reducers throughout the anoxic sediment column. In the absence of sulfate, Syntrophomonas and Cyrptanaerobacter become dominant which suggests their role in syntrophic butyrate and propionate conversion, respectively. These results were further supported in Chapter 6. The increase in the relative abundance of Syntrophomonas in the presence of sulfate (Chapter 3) and some members of Desulfobacteraceae (Chapter 4) in the absence of sulfate shows the metabolic flexibility of the microorganisms at different sulfate concentrations. Temperature has an impact on the microbial community (Chapter 4) and IPL composition (Chapter 5) in enrichment slurries. Cryptanaerobacter is dominant at 25°C, and, Desulfobacteraceae (Desulfofaba), especially Desulfobulbaceae members (Desulfobulbus, Desulforhopalus) become dominant at 10°C at 0 and 3 mM sulfate concentrations in propionate-amended enrichment slurries. In butyrate-amended slurries, Clostridiales have higher relative abundance at 10°C regardless of the sulfate concentration and the sediment depth which supports important role of Clostridiales in butyrate conversion in marine sediments. Archaeal community analyses revealed the dominance of hydrogenotrophic methanogens belonging to Methanomicrobiales in both butyrate- and propionate-converting slurries (Chapter 3 and 4) and enrichment cultures (Chapter 6) regardless of the sediment depth, the incubation temperature and the presence of sulfate, which indicate that they are the main syntrophic partners of butyrate and propionate degraders. The other syntrophic partner organisms are the aceticlastic methanogenic families: Methanosarcinaceae and Methanosaetaeceae. The presence of methane-oxidizing archaea (ANME-1b) in low temperature SMTZ slurries together with Desulfobacteraceae (Chapter 3 and 4) suggests the occurrence of anaerobic oxidation of methane (AOM) in SMTZ of Aarhus Bay.

In conclusion, this thesis confirms the presence and activity of methanogens in sulfate-rich, and SRB in sulfate-depleted marine sediments; and their involvement in butyrate, propionate and acetate conversion. Novel bacterial and archaeal members enriched in the sediment slurries are likely involved in propionate, butyrate and acetate conversions at different depths of marine sediments in addition to known the cultured species.

De effecten van gereduceerde grondbewerking : groenbemesters beschermen bodem in winter en verminderen onkruiddruk in groeiseizoen
Balen, D.J.M. van; Leeuwen-Haagsma, W.K. van - \ 2017
Ekoland 37 (2017)5. - ISSN 0926-9142 - p. 12 - 13.
groenbemesters - biologische landbouw - bodemkwaliteit - bodem - bodembiologie - organische stof - gereduceerde grondbewerking - green manures - organic farming - soil quality - soil - soil biology - organic matter - reduced tillage
Binnen de biologische landbouw was er altijd extra aandacht voor bodemkwaliteit. De bodem voedt de plant tenslotte. Intussen beginnen wat meer te leren over welke processen er zich in de bodem afspelen. En over de rol die planten spelen. Naast gewas- en rassenkeuze kunnen groenbemesters en mengsels van gewassen en groenbemesters een belangrijke rol spelen. Zo kan ook de plant de bodem voeden.
Simulation nitrogen-limited crop growth with SWAP/WOFOST : process descriptions and user manual
Groenendijk, Piet ; Boogaard, Hendrik ; Heinen, Marius ; Kroes, J.G. ; Supit, Iwan ; Wit, Allard de - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2721) - 59
crops - growth - soil - nitrogen - organic matter - mineralization - leaching - simulation models - nitrates - gewassen - groei - bodem - stikstof - organische stof - mineralisatie - uitspoelen - simulatiemodellen - nitraten
This report describes a soil nitrogen module (Soil-N), which is combined with the agro-hydrological model, SWAP, and the crop growth model, WOFOST. The core of the Soil-N module is a description of the nitrogen cycle, which is coupled to the organic matter cycle based upon the RothC-26.3 model. Nitrogen can be supplied to the soil as different types of fertilizer applications and through mineralisation of organic nitrogen. Ammonium and nitrate balances are calculated including uptake by plant roots, de-nitrification and leaching of nitrate. Data exchange is on a daily base. The partitioning of nitrogen within crops and the nitrogen contents of crop residues are calculated by WOFOST and passed to the Soil-N module. SWAP generates the data for establishing the water balance of the soil compartment for which the Soil-N perform the simulations. Nitrogen uptake by the crop is calculated as the minimum of the demand by the crop and the availability of nitrogen in the soil. The crop production rate is reduced when the mineral nitrogen stock is limited. Nitrogen-fixation is based on a simple approach. An improved sub-model for phenological stages of soybean was implemented. Increasing atmospheric CO2 concentrations can be accounted for. The innovated integrated model was tested using data sets from The Netherlands, China and Argentina, for which examples are given. This new model can be used as a tool in studies, in which both water and nitrogen can be limited for crop growth.
Visie integraal bodembeheer Algemeen
Haan, Janjo de - \ 2016
arable farming - soil management - water management - soil quality - soil fertility - farm management - rotations - fertilizer application - tillage - agricultural production - biodiversity - climatic factors - ecosystem services - organic matter - teaching materials
Goed organisch stofbeheer
Tramper, Marcel - \ 2016
arable farming - soil structure - organic matter - trace elements - uptake - green manures - chopping - tillage - ploughing - teaching materials - farm management
Vrijloopstallen Utrecht
Galama, P.J. ; Boer, H.C. de; Dooren, H.J.C. van; Kasper, G.J. - \ 2015
Lelystad : Wageningen UR Livestock Research - 45
melkvee - loopstallen - vloeren - ligstro - organische stof - houtspaanders - bagger - ammoniakemissie - utrecht - dierenwelzijn - dairy cattle - loose housing - floors - litter - organic matter - wood chips - dredgings - ammonia emission - animal welfare
De afgelopen jaren heeft de huisvesting van melkvee een grote ontwikkeling doorgemaakt. In de jaren 60 van de vorige eeuw werd de ligboxenstal geïntroduceerd als vervanger van de grupstal. Het belangrijkste doel hiervan was het verbeteren van de arbeidsefficiëntie waardoor boeren meer koeien konden houden. Met de ligboxenstal veranderde ook de mestopslag van een gescheiden systeem voor gier en vaste mest in een systeem voor drijfmest. Ook kregen de koeien meer bewegingsruimte. De afgelopen jaren namen de eisen ten aanzien van welzijn en milieu steeds verder toe, wat geleid heeft tot aanpassing van afmetingen, vloeren, mestopslagsystemen en ventilatie in ligboxenstallen. Toch hebben sommige melkveehouders behoefte aan een stal die enerzijds de koeien nog meer bewegingsruimte geeft dan een ligboxenstal en anderzijds mest oplevert met een hoger organische stof gehalte dan drijfmest. De Provincie Utrecht stimuleert innovatieve stallenbouw.
Producten uit rundermest : de landbouwkundige waarde onderzocht
Curth-van Middelkoop, J.C. ; Verdoes, N. - \ 2015
V-focus 12 (2015)3. - ISSN 1574-1575 - p. 18 - 19.
rundveehouderij - rundveemest - mestverwerking - mestoverschotten - mineralen - rundveedrijfmest - raffineren - organische stof - cattle husbandry - cattle manure - manure treatment - manure surpluses - minerals - cattle slurry - refining - organic matter
Sinds 2014 zijn veehouders verplicht een deel van hun mestoverschot te laten verwerken. Veehouders kunnen dit regelen door mestverwerkingsovereenkomsten af te sluiten met mestverwerkers. Dit artikel beschrijft de landbouwkundige waarde van diverse meststoffen die verwerking van rundermest oplevert.
Ecologie van bosbodems : een verkennende studie naar ecologisch functioneren van bosbodems op zandgronden
Jong, J.J. de; Bloem, J. ; Delft, S.P.J. van; Hommel, P.W.F.M. ; Oosterbaan, A. ; Waal, R.W. de - \ 2015
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2657) - 89
bosecologie - bodemecologie - bodemvruchtbaarheid - humus - organische stof - zandgronden - forest ecology - soil ecology - soil fertility - organic matter - sandy soils
De bodem van een bos is bepalend voor het functioneren van het bos als productie- en ecosysteem. Het is het substraat waar organismen in leven en waar planten in wortelen. De bodem houdt vocht en nutriënten vast en levert deze aan planten en het bodemleven, terwijl planten organische stof aan de bodem leveren. De wijze waarop dit allemaal gebeurt, bepaalt in grote mate welke organismen er in en op voor kunnen komen en hoe die functioneren. De bodemorganismen en voedingstoestand van de bodem worden beïnvloed door beheer en externe factoren, zoals depositie. Kennis van de onderlinge relaties tussen de factoren die de bodemvruchtbaarheid bepalen of door de bodemvruchtbaarheid bepaald worden, is daarom van groot belang voor een duurzaam bosbeheer. Dit rapport bevat een verkenning van de kennis die er aanwezig is op dat gebied.
Tot de bodem uitzoeken : micro-organismen beïnvloeden plantengroei
Beintema, N. ; Groenigen, J.W. van - \ 2015
WageningenWorld (2015)2. - ISSN 2210-7908 - p. 10 - 15.
bodembiologie - bodembeheer - organische stof - aardwormen - bodemkwaliteit - organisch bodemmateriaal - koolstof - micro-organismen - bodemvruchtbaarheid - gewasbescherming - plantenontwikkeling - soil biology - soil management - organic matter - earthworms - soil quality - soil organic matter - carbon - microorganisms - soil fertility - plant protection - plant development
Per vierkante meter bodem leven honderden wormen en insecten samen met kilometers aan schimmeldraden, vele miljoenen aaltjes en miljarden bacteriën. Onderzoek maakt steeds meer duidelijk van het precaire evenwicht ondergronds, en de grote invloed daarvan op het leven bovengronds. Het levert nieuwe strategieën op voor gewasbescherming.
Verdichting voorkomen is cruciaal : de bodem onder een vruchtbare kringloop
Eekeren, N.J.M. van; Rietberg, P.I. ; Gerner, L. ; Leeuwen, M.W.J. van - \ 2015
V-focus 12 (2015)2. - ISSN 1574-1575 - p. 20 - 21.
graslandbeheer - bodembiologie - bodemkwaliteit - bodemdichtheid - kringlopen - organische stof - waterschappen - achterhoek - liemers - grassland management - soil biology - soil quality - soil density - cycling - organic matter - polder boards
In het project Vruchtbare Kringloop werken - naast een samenwerking van LTO Noord, ForFarmers Hendrix, Waterschap Rijn en IJssel, Provincie Gelderland, Rabobank en Vitens - 250 agrariërs in de Achterhoek en Liemers middels de KringloopWijzer aan optimalisatie van hun bedrijfsvoering. Het doel is voorop te lopen met kringlooplandbouw, meststoffen optimaal te benutten en de bodem- en waterkwaliteit te verbeteren. Bodemkwaliteit is een belangrijk aspect in de KringloopWijzer: verhoging van de bodembenutting van N met 20 procent leidt tot een stijging van de bedrijfsbenutting van N van 10 procent. Dit artikel gaat in op de belangrijkste knelpunten in bodemkwaliteit op grasland aan de hand van de resultaten van de BodemConditieScore.
Doorontwikkeling biologische grondontsmetting (bodemresetten) als alternatief voor stomen
Garcia Victoria, N. ; Helm, F.P.M. van der; Streminska, M.A. ; Roelofs, T. - \ 2015
Wageningen : Wageningen UR Glastuinbouw (Rapport GTB 1342) - 68
biologische grondontsmetting - organische stof - grondbewerking - biologische processen - alternatieve methoden - bodemstructuur - glastuinbouw - proeven - energiebesparing - biological soil sterilization - organic matter - tillage - biological processes - alternative methods - soil structure - greenhouse horticulture - trials - energy saving
Biological Soil Disinfection (BSD) or ‘soil resetting’ can technically, energetically and economically be an effective alternative to soil steaming. The program ‘Greenhouse as energy source’ of the Ministry of Economy, Agriculture and Innovation and the Dutch Horticultural Board gave fi nancial support to practical demonstrations and further development of this technology, in order to stimulate implementation of BSD in practice. Chrysanthemum growers, DLV Plant B.V., Wageningen UR Greenhouse Horticulture and Thatchtec B.V. gained experience with BSD in four chrysanthemums companies. Additional research was conducted into possibilities to speed up the process and fi nd reliable process indicators. The disinfection and cultivation results (up to 5 cycles) was after BSD as good or better as after steaming in 3 of the 4 companies. Anaerobic conditions, one of the prerequisites for disinfection, were not achieved in the fourth company, which may explain the unsatisfactory disinfection. In intensive cultivation, three weeks without cultivation need to be included in the planning. Implementation in July offers the best fi t in terms of effectivity and income.The process can be shortened to 9 days by means of a higher Raw Proteine dose, but this leads to growth inhibition in the next cultivation. Adding a “primer” or “inoculum” with own soil bacteria does not suffi ciently increase the operational reliability, and is therefore deleted as a process step in the protocol. The disinfection process can be well monitored by means of oxygen measurement and total nematode counts. Additional indicators are the concentrations of nitrate, ammonium and bicarbonate in the 1:2 soil volume extract.
Alternatieve fosfaat-arme organische materialen voor de bollenteelt : Effect op organisch stof gehalte en bodemvrucht
Os, G.J. van; Lans, A.M. van der; Bent, J. van der - \ 2015
Lisse : Praktijkonderzoek Plant & Omgeving BBF - 37
bodem - organische stof - bodemkwaliteit - bloembollen - fosfaten - bodemvruchtbaarheid - duingebieden - bodemwater - soil - organic matter - soil quality - ornamental bulbs - phosphates - soil fertility - duneland - soil water
Een voldoende hoog organisch stofgehalte in de bodem is nodig voor een goede bodem- en waterkwaliteit en een optimale teelt. Dit rapport beschrijft de resultaten van een tweejarige veldproef op duinzandgrond naar de effecten van fosfaat-arme alternatieven voor huidige organische meststoffen, waarmee telers het bodem organische stofgehalte op peil kunnen houden. In de bollenteelt op duinzandgrond worden stalmest, GFT-compost en groenbemesters toegepast voor het organisch stof management. Dit is een lastige opgave binnen de aangescherpte gebruiksnormen in de mest- en mineralen wetgeving. De aanvoernorm voor fosfaat is de eerste waar telers tegenaan lopen. Op basis van een inventarisatie, uitgevoerd door CLM en PPO (Van Os et al., 2012), heeft het MilieuPlatform een drietal materialen geselecteerd met een gunstiger organische stof/fosfaat verhouding dan die van stalmest en GFT-compost: cacaodoppen, kokosvezels en Biochar. De resultaten uit het onderzoek geven een indicatie van de mate van geschiktheid van deze materialen voor toepassing in de bollenteelt. De beoordeling van de organische materialen heeft plaatsgevonden op basis van de volgende criteria: goede verwerkbaarheid, effecten op vochtvasthoudend vermogen van de grond, de beschikbaarheid van nutriënten N en P, de bolopbrengst, het organische stof gehalte in de bodem en op de bodemweerbaarheid. In de veldproef zijn twee doseringen toegediend van cacaodoppen, kokosvezels en biochar en vergeleken met GFT-compost. Alle materialen waren goed verwerkbaar, maar elk had z’n eigen voor- en nadelen bij de overige criteria. Toediening heeft geleid tot: • Significante verhoging van het organisch stof gehalte in de bodem bij de hoge dosering van cacaodoppen en biochar • Verhoging van het vochtvasthoudend vermogen bij alle organische materialen • Verhoging van de bolopbrengst alleen bij compost en de hoge dosering kokosvezels • Kans op stikstofimmobilisatie bij de hoge dosering van kokosvezels en biochar; hiermee moet rekening worden gehouden bij de bemesting. • Verhoging van NPK-gehaltes in de bol bij hoge dosering van cacaodoppen • Verhoging van de bodemweerbaarheid tegen Pythium, Rhizoctonia solani (bolaantasting) en Meloïdogyne hapla (noordelijk wortelknobbelaaltje) via biologische èn fysisch-chemische mechanismen. Op basis van de gemeten waarden kan het volgende worden afgeleid: • De afbraaksnelheid van de materialen neemt toe in de volgorde: biochar (meest persistent), cacaodoppen, compost, kokosvezels (relatief makkelijk afbreekbaar) • De potentiële verhoging van het bodem organisch stof gehalte bij de maximaal toegestane dosering (op basis van fosfaat-aanvoernorm) neemt toe in de volgorde: cacaodoppen (minste verhoging), Biochar/compost, kokosvezels (grootste verhoging) • Met kokosvezels kan (in theorie) het organisch stof gehalte in de bodem het meest efficiënt worden verhoogd binnen de aanvoernorm, vanwege het extreem lage fosfaatgehalte. Bij gelijke hoeveelheid organische stof is de kostprijs van de geteste materialen (gebaseerd op de huidige leveringshoeveelheden) in alle gevallen aanzienlijk hoger dan die van GFT-compost. Volledige vervanging van compost en stalmest door een van de alternatieve producten lijkt, vanwege de diverse nadelen, niet reëel. Een optimale toediening van organische materialen zal daarom in de praktijk neerkomen op een slimme combinatie van verschillende producten, die gezamenlijk alle gewenste functies van organische stof in de bodem vervullen. Organische stof management is een proces van de lange adem, waarbij de samenstelling van (het mengsel van) de organische producten is belangrijk is. Bij regelmatige toediening van grote hoeveelheden zijn de effecten onbekend. Hiervoor is langjarig onderzoek nodig.
Bodemfysische gegevens in BIS
Bakker, G. ; Heinen, M. ; Wesseling, J.G. ; Groot, W.J.M. de; Assinck, F.B.T. ; Hummelink, E.W.J. - \ 2015
Wageningen : Alterra (Alterra-rapport 2613)
bodemfysica - bodemwater - organische stof - informatiesystemen - soil physics - soil water - organic matter - information systems
Bodemfysische gegevens, zoals de waterretentiekarakteristiek en doorlatendheidskarakteristiek, organisch stofgehalte, textuurgegevens, profielbeschrijving en andere metagegevens zijn belangrijke basisgegevens bij het modelleren van transport van water en opgeloste stoffen in de onverzadigde zone, maar vinden ook tal van andere toepassingen. Omdat er grote behoefte is aan actuele bodemfysische gegevens van hoge kwaliteit en omdat de huidige databases onvoldoende opschalingsmogelijkheden bieden, zijn in dit project 100 nieuwe bodemfysische gegevens van goede kwaliteit gegenereerd. De bodemfysische gegevens en de bijbehorende beschrijvende gegevens zijn ondergebracht in het BIS (Bodem Informatie Systeem). Aanvullend is van 91 bestaande bodemfysische gegevens van hoge kwaliteit in Priapus een koppeling gelegd met beschrijvende gegevens in BIS en de literatuur, zodat er in totaal 191 bodemfysische monsters beschikbaar zijn.
Waarde van organische stof in project Bodemkwaliteit op Zandgrond
Haan, J.J. de; Spruijt, J. ; Verstegen, H.A.G. - \ 2015
akkerbouw - bemesting - bodemkwaliteit - zandgronden - organische stof - landbouwprijzen - berekening - arable farming - fertilizer application - soil quality - sandy soils - organic matter - agricultural prices - calculation
In het project Bodemkwaliteit op zandgrond zijn de baten van organische stofaanvoer uitgerekend. In het bouwplan van de proef blijkt de waarde van effectieve organische stof (EOS) gemiddeld 60 cent per kg te zijn. EOS is het deel van de aangevoerde organische stof met mest, gewasresten of groenbemesters die na 1 jaar nog over is in de bodem. De waarde varieert sterk en is afhankelijk van de prijs van het product en het effect van organische stofaanvoer op opbrengst. Op basis hiervan kan de prijs van mestproducten berekend worden
Dynamics in organic matter processing, ecosystem metabolism and trophic sources for consumers in the Mara River, Kenya
Masese, F.O. - \ 2015
Wageningen University. Promotor(en): K.A. Irvine, co-promotor(en): M.E. McClain; G.M. Gettel. - Leiden : CRC Press/Balkema - ISBN 9781138028159 - 195
organische stof - ecosystemen - landgebruik - ecosysteemdiensten - rivieren - meren - koolstof - stikstof - visserij - aquatische ecologie - organic matter - ecosystems - land use - ecosystem services - rivers - lakes - carbon - nitrogen - fisheries - aquatic ecology

To properly conserve, restore and manage riverine ecosystems and the services they provide, it is pertinent to understand their functional dynamics. However, there is still a major knowledge gap concerning the functioning of tropical rivers in terms of energy sources supporting riverine fisheries. I reviewed the anthropogenic influences on organic matter processes, energy sources and attributes of riverine food webs in the Lake Victoria basin, but also expanded the review to incorporate recent research findings from the tropics. Contrasting findings have been presented on the diversity of shredders and their role in organic matter processing in tropical streams. Recent tropical research has also highlighted the importance of autochthonous carbon, even in small forested streams. However similar studies are very limited in Afrotropical streams making it difficult to determine their place in emerging patterns of carbon flow in the tropics.

This study was conducted in the Mara River, which is an important transboundary river with its headwaters in the Mau Forest Complex in Kenya and draining to Lake Victoria through Tanzania. In its headwaters, the basin is drained by two main tributaries, the Amala and Nyangores Rivers which merge in the middle reaches to form the Mara River mainstem. The overall objective of this dissertation was to better understand the functioning of the Mara River by assessing the spatio-temporal dynamics of organic matter sources and supply under different land-use and flow conditions and the influence of these dynamics on energy flow for consumers in the river. I collected benthic macroinvertebrates from open- and closed-canopy streams and classified them into functional feeding groups (FFGs) using gut content analysis. In total, I identified 43 predators, 26 collectors, 19 scrapers and 19 shredders. Species richness was higher in closed-canopy forested streams where shredders were also the dominant group in terms of biomass. Seven shredder taxa occurred only in closed-canopy forested streams highlighting the importance of maintaining water and habitat quality, including the input of leaf litter of the right quality, in the studied streams. The findings suggest that Kenyan highland streams harbor a diverse shredder assemblage contrary to earlier findings that had identified a limited number of shredder taxa.

I subsequently used the composition of invertebrate functional feeding groups (FFGs) and the ecosystem process of leaf breakdown as structural and functional indicators, respectively, of ecosystem health in upland Kenyan streams. Coarse- and fine-mesh litterbags were used to

compare microbial (fine-mesh) with shredder + microbial (coarse-mesh) breakdown rates, and by extension, determine the role of shredders in litter processing of leaves of different tree species (native Croton macrostachyus and Syzygium cordatum and the exotic Eucalyptus globulus). Breakdown rates were generally higher in coarse- compared with fine-mesh litterbags for the native leaf species and the relative differences in breakdown rates among leaf species remained unaltered in both agriculture and forest streams. Shredders were relatively more important in forest compared with agriculture streams where microbial breakdown was more important. Moreover, shredder mediated leaf litter breakdown was dependent on leaf species, and was highest for C. macrostachyus and lowest for E. globulus, suggesting that replacement of indigenous riparian vegetation with poorer quality Eucalyptus species along streams has the potential to reduce nutrient cycling in streams.

To study organic matter dynamics is these streams, I assessed the influence of land use change on the composition and concentration of dissolved organic matter (DOM) and investigated its links with whole-stream ecosystem metabolism. Optical properties of DOM indicated notable shifts in composition along a land use gradient. Forest streams were associated with higher molecular weight and terrestrially derived DOM whereas agriculture streams were associated with autochthonously produced and low molecular weight DOM and photodegradation due to the open canopy. However, aromaticity was high at all sites irrespective of catchment land use. In agricultural areas high aromaticity likely originated from farmlands where soils are mobilized during tillage and carried into streams and rivers by runoff. Gross primary production (GPP) and ecosystem respiration (ER) were generally higher in agriculture streams, because of slightly open canopy and higher nutrient concentrations. The findings of this study are important because, in addition to reinforcing the role of tropical streams and rivers in the global carbon cycle, they highlight the consequences of land use change on ecosystem functioning in a region where land use activities are poised to intensify in response to human population growth.

Lastly, I used natural abundances of stable carbon (δ13C) and nitrogen (δ15N) isotopes to quantify spatial and temporal patterns of carbon flow in food webs in the longitudinal gradient of the Mara River. River reaches were selected that were under different levels of human and mammalian herbivore (livestock and wildlife) influences. Potential primary producers (terrestrial C3 and C4 producers and periphyton) and consumers (invertebrates and fish) were collected

during the dry and wet seasons to represent a range of contrasting flow conditions. I used Stable Isotope Analysis in R (SIAR) Bayesian mixing model to partition terrestrial and autochthonous sources of organic carbon supporting consumer trophic groups. Overall periphyton dominated contributions to consumers during the dry season. During the wet season, however, the importance of terrestrially-derived carbon for consumers was higher with the importance of C3 producers declining with distance from the forested upper reaches as the importance of C4 producers increased in river reaches receiving livestock and hippo inputs. This study highlights the importance of large mammalian herbivores on the functioning of riverine ecosystems and the implications of their loss from savanna landscapes that currently harbour remnant populations.

The results of this dissertation contribute data to discussions on the effects of land use change on the functioning of upland streams and food webs in savanna rivers with regard to carbon flow and the vectoring role played by large mammalian herbivores as they transfer terrestrial organic matter and nutrients into streams and rivers. This study also provides information and recommendations that will guide future research and management actions for the sustainability of the Mara River and linked ecosystems in the Lake Victoria basin.

Door regelgeving kan het vaak niet zoals je wil
PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2015
Akker magazine 11 (2015)2. - ISSN 1875-9688 - p. 12 - 13.
akkerbouw - duurzaam bodemgebruik - duurzame landbouw - fosfaat - organische stof - bodembeheer - sensors - zeeland - nederland - arable farming - sustainable land use - sustainable agriculture - phosphate - organic matter - soil management - netherlands
Winnaar van de wedstrijd Topbodem, editie 2014-15, Hans Akkermans probeert alles te doen om zijn bodem in topconditie te houden. Toch merkt hij dat de normen voor fosfaat de ruimte beperken om aan duurzame bodemvruchtbaarheid te werken. Voor een goed saldo neigt hij naar intensievere teelten, voor de bodem naar voldoende rustgewassen.
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