Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Current refinement(s):

    Records 1 - 20 / 102

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Organische mestkwaliteit beïnvloedt bodemmicroben en bodemfuncties
    Heijboer, A. ; Berge, H.F.M. ten; Ruiter, P.C. de; Kowalchuk, G.A. ; Jorgensen, H.B. ; Bloem, J. - \ 2016
    Landschap : tijdschrift voor landschapsecologie en milieukunde 27-29 (2016). - ISSN 0169-6300 - p. 27 - 29.
    agro-ecosystemen - bemesting - bodembiologie - micro-organismen - bodemmicrobiologie - stikstofkringloop - fosfolipiden - veldproeven - brassica oleracea var. gemmifera - agroecosystems - fertilizer application - soil biology - microorganisms - soil microbiology - nitrogen cycle - phospholipids - field tests - brassica oleracea var. gemmifera
    Micro-organismen spelen een sleutelrol in bodemfuncties zoals de kringlopen van koolstof en stikstof. Voor een duurzame landbouw is het van belang dat deze kringlopen optimaal functioneren om verliezen van nutriënten zoveel mogelijk te voorkomen. Dit onderzoek geeft inzicht in de rol van bodemmicroben bij optimalisatie van de stikstofkringloop door toevoeging van zowel minerale kunstmest als verschillende kwaliteiten organisch materiaal.
    Functionele diversiteit mycorrhizaschimmels onder druk door stikstofdepositie
    Ozinga, W.A. ; Kuijper, Thomas - \ 2015
    Vakblad Natuur Bos Landschap 12 (2015)117. - ISSN 1572-7610 - p. 20 - 22.
    mycorrhizaschimmels - functionele biodiversiteit - stikstof - stikstofkringloop - depositie - ecosystemen - bosgebieden - mycorrhizal fungi - functional biodiversity - nitrogen - nitrogen cycle - deposition - ecosystems - woodlands
    Bosbodems kunnen veel verschillende ectomycorrhiza-vormende schimmels herbergen. In de herfst is een glimp van deze ondergrondse rijkdom te zien via de vorming van vruchtlichamen (‘paddenstoelen’). De ectomycorrhizaschimmels spelen een belangrijke rol bij onder andere de nutriëntenkringloop, de vastlegging van koolstof en de natuurlijke regeneratie van bomen. Hoge stikstofgehaltes in de bodem leiden echter tot een sterke afname van de abundantie en diversiteit aan mycorrhizaschimmels en dit kan doorwerken in het hele ecosysteem.
    KringloopWijzer moet inspireren
    Haan, M.H.A. de; Aarts, H.F.M. - \ 2015
    Grondig : vakblad voor de cumelasector, specialisten in groen, grond en infra (2015)5. - ISSN 2210-3260 - p. 40 - 41.
    akkerbouw - kringlopen - stikstofkringloop - veehouderij - milieueffect - gewasopbrengst - mineralenopname - bemesting - fosfaat - koolstof - arable farming - cycling - nitrogen cycle - livestock farming - environmental impact - crop yield - mineral uptake - fertilizer application - phosphate - carbon
    De komende jaren moeten melkveehouders verplicht gaan werken met de KringloopWijzer. Dat heeft als doel ze bewuster te maken van hun bedrijfsprestaties en de manier waarop ze de mineralenstroom kunnen sturen. In dit artikel leggen de grondleggers van het systeem uit hoe de KringloopWijzer werkt en waarom dit voor loonbedrijven van belang is.
    NPK balans, N-verlies en beddingsamenstelling van vrijloopstal Hoogland in 2014
    Boer, H.C. de - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 886) - 24
    rundvee - huisvesting van koeien - loopstallen - dierenwelzijn - stikstofkringloop - stikstof - vervluchtiging - bemesting - vergelijkingen - landbouw en milieu - stikstofverliezen - dierlijke productie - melkvee - milieu - cattle - cow housing - loose housing - animal welfare - nitrogen cycle - nitrogen - volatilization - fertilizer application - comparisons - agriculture and environment - nitrogen losses - animal production - dairy cattle - environment
    Een aantal Nederlandse melkveehouders stapt de laatste jaren over van een ligboxenstal met roostervloer naar een vrijloopstal zonder boxen en met een organische bedding. Een belangrijke reden voor deze overstap is het realiseren van een beter dierenwelzijn in de stal. Naast een beter dierenwelzijn heeft de overstap ook andere effecten, waaronder op de stikstofkringloop op het bedrijf. Stikstof (N) verdwijnt uit deze kringloop onder andere door vervluchtiging uit de stal, uit de mestopslag en na het uitrijden van mest op het land. N kan vervluchtigen in de vorm van ammoniak (NH3), lachgas (N2O), stikstofgas (N2) en overige stikstofoxiden (NOx). De vervluchtiging van ammoniak kan bijdragen aan verzuring en eutrofiëring van de natuur en vervluchtiging van lachgas aan opwarming van de aarde. De vervluchtiging van stikstofgas heeft geen directe negatieve effecten op de omgeving. Echter, door het verdwijnen van N uit de bedrijfskringloop moet er wel meer N op het bedrijf aangevoerd worden om de productiviteit van de bodem, de gewassen en de koeien op niveau te houden. Gebeurt dit met dierlijke mest of kunstmest, dan leidt dit alsnog tot een hogere milieubelasting. Gezien de bovenstaande consequenties is het wenselijk om de N-vervluchtiging op het melkveebedrijf zo laag mogelijk te houden. Om inzicht te krijgen in milieu- en productiviteitseffecten van de omschakeling van een ligboxenstal naar een vrijloopstal is het dus nodig om inzicht te krijgen in de hoeveelheid N die vervluchtigt uit de vrijloopstal en deze te vergelijken met de ligboxenstal. N vervluchtigt niet alleen uit de stal maar ook na het uitrijden van mest uit de stal op het land. Een stalsysteem met een relatief lage Nvervluchtiging direct uit de stal kan een relatief hoge N-vervluchtiging na mesttoediening hebben, en omgekeerd. Bij de ligboxenstal met productie van drijfmest wordt bijna de helft van de totale Nvervluchtiging (stal + land) na het emissiearm uitrijden van de mest op het land gerealiseerd (zie paragraaf 2.4). Om een meer volledig en betrouwbaar beeld te hebben van de N-vervluchtiging van een stalsysteem is het daarom gewenst om de N-vervluchtiging direct uit de stal en na mestaanwending gezamenlijk te beoordelen.
    Ontwikkeling van de N-balans, het N-verlies en de beddingsamenstelling van vrijloopstal Hartman in 2013/2014
    Boer, H.C. de - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 885) - 43
    stikstofbalans - stikstofverliezen - stallen - landbouwschuren - huisvesting van koeien - stikstofkringloop - melkveehouderij - duurzame veehouderij - mest - landbouw en milieu - rundveehouderij - dierenwelzijn - loopstallen - nitrogen balance - nitrogen losses - stalls - barns - cow housing - nitrogen cycle - dairy farming - sustainable animal husbandry - manures - agriculture and environment - cattle husbandry - animal welfare - loose housing
    Een aantal Nederlandse melkveehouders stapt de laatste jaren over van een ligboxenstal met een roostervloer naar een vrijloopstal met een organische bedding. Deze overstap heeft meerdere effecten, waaronder op de stikstofkringloop op het melkveebedrijf. Stikstof (N) verdwijnt uit deze kringloop onder andere door vervluchtiging uit de stal, uit de mestopslag en na het uitrijden van mest op het land. N-vervluchtiging kan negatieve effecten hebben op de milieukwaliteit en leiden tot verlies van productiviteit. Daarom is het wenselijk om het N-verlies door vervluchtiging op het melkveebedrijf zo laag mogelijk te houden. Het onderzoek in dit rapport richtte zich op het vaststellen van het totale N-verlies door vervluchtiging uit de vrijloopstal van de familie Hartman in Heibloem (Limburg).
    Ontwikkeling van de N-balans, het N-verlies en de beddingsamenstelling van vrijloopstal Ottema-Wiersma in 2013/2014
    Boer, H.C. de - \ 2015
    Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 881)
    huisvesting van koeien - melkveehouderij - stikstofbalans - stikstofverliezen - stikstofkringloop - vervluchtiging - rundveemest - stalinrichting - loopstallen - rundveeteelt - dierenwelzijn - landbouw en milieu - cow housing - dairy farming - nitrogen balance - nitrogen losses - nitrogen cycle - volatilization - cattle manure - animal housing design - loose housing - cattle farming - animal welfare - agriculture and environment
    Een aantal Nederlandse melkveehouders stapt de laatste jaren over van een ligboxenstal met een roostervloer naar een vrijloopstal met een organische bedding. Deze overstap heeft meerdere effecten, waaronder op de stikstofkringloop op het melkveebedrijf. Het onderzoek in dit rapport richtte zich op het vaststellen van het N-verlies door vervluchtiging uit de vrijloopstal van de VOF Ottema-Wiersma in Midwolde (Groningen).
    Nitrogen : too much of a vital resource : Science Brief
    Erisman, J.W. ; Galloway, J.N. ; Dise, N.B. ; Sutton, M.A. ; Bleeker, A. ; Grizzetti, B. ; Leach, A.M. ; Vries, W. de - \ 2015
    Zeist, The Netherlands : WWF Netherlands (WWF science brief NL ) - ISBN 9789074595223 - 27
    stikstofkringloop - waterverontreiniging - eutrofiëring - emissiereductie - broeikasgassen - terrestrische ecosystemen - wetenschappelijk onderzoek - milieubeleid - nitrogen cycle - water pollution - eutrophication - emission reduction - greenhouse gases - terrestrial ecosystems - scientific research - environmental policy
    It is now clear that the nitrogen problem is one of the most pressing environmental issues that we face. But in spite of the enormity of our influence on the N cycle and consequent implications for the environment and for human well-being, there is surprisingly little attention paid to the issue. While biodiversity loss and climate change have spawned huge budgets to create national and multidisciplinary programs, global organizations, political and media attention, the N challenge remains much less apparent in our thinking and actions. This is because we are educated with the important role that N plays with regard to food security. This paper aims to contribute to the understanding of the N challenge, and to provide options for decreasing the negative impacts of excess N.
    Invloed bedrijfsvoering akkerbouwers op financieel resultaat en stikstofhuishouding
    Prins, H. ; Daatselaar, C.H.G. - \ 2013
    Wageningen : LEI, onderdeel van Wageningen UR (LEI report 2013-065) - ISBN 9789086156603 - 78
    akkerbouw - bedrijfsresultaten in de landbouw - stikstofkringloop - waterkwaliteit - monitoring - bodemtypen - zandgronden - zware kleigronden - arable farming - farm results - nitrogen cycle - water quality - monitoring - soil types - sandy soils - clay soils
    Onder de vlag van het Landelijk Meetnet effecten Mestbeleid (LMM) heeft het LEI de invloed onderzocht van de bedrijfsstructuur en de bedrijfsvoering van akkerbouwbedrijven op het stikstofoverschot, de waterkwaliteit en de financiële bedrijfsresultaten. Met behulp van regressieanalyse met paneldata is nagegaan hoe groot de invloed is van de bedrijfsstructuur en die van de bedrijfsvoering. Het onderzoek betrof de periode 1991-2009, waarbij onderscheid is gemaakt tussen de grondsoorten zand, klei en löss.
    Soil biota and nitrogen cycling in production grasslands with different fertilisation histories
    Rashid, M.I. - \ 2013
    Wageningen University. Promotor(en): Lijbert Brussaard, co-promotor(en): Egbert Lantinga; Ron de Goede. - S.l. : s.n. - ISBN 9789461735485 - 192
    stikstofkringloop - bodemfauna - mineralisatie - rundveemest - decompositie - bodeminvertebraten - bodem ph - aardwormen - graslanden - bodembiologie - nitrogen cycle - soil fauna - mineralization - cattle manure - decomposition - soil invertebrates - soil ph - earthworms - grasslands - soil biology
    Our nutrient world. The challenge to produce more food & energy with less pollution
    Sutton, M.A. ; Bleeker, A. ; Howard, C.M. ; Erisman, J.W. ; Abrol, Y.P. ; Bekunda, M. ; Datta, A. ; Davidson, E. ; Vries, W. de; Oenema, O. ; Zhang, F.S. - \ 2013
    Edinburgh : Centre for Ecology & Hydrology (Key messages for Rio+20 ) - 114
    nutrientenbeheer - kringlopen - stikstofkringloop - fosfor - voedselzekerheid - milieubeleid - duurzaamheid (sustainability) - nutrient management - cycling - nitrogen cycle - phosphorus - food security - environmental policy - sustainability
    The message of this overview is that everyone stands to benefit from nutrients and that everyone can make a contribution to promote sustainable production and use of nutrients. Whether we live in a part of the world with too much or too little nutrients, our daily decisions can make a difference. Without swift and collective action, the next generation will inherit a world where many millions may suffer from food insecurity caused by too few nutrients, where the nutrient pollution threats from too much will become more extreme, and where unsustainable use of nutrients will contribute even more to biodiversity loss and accelerating climate change. Conversely with more sustainable management of nutrients, economies can play a role in a transition to a Green Economy in the context of sustainable development and poverty eradication. The Global Overview develops these essential themes, to prepare societies to take the next steps.
    Implementing water protection policy at farm level in the European Union: lessons from the N-Toolbox case studies
    Cooper, J. ; Burgt, G.J.H.M. van der; Kristensen, H. ; Quemada, M. ; Carmichael, A. ; Gascoyne, K. ; Timmermans, B.G.H. ; Rietberg, P.I. - \ 2012
    Newcastle : Newcastle University - 21 p.
    waterkwaliteit - oppervlaktewaterkwaliteit - grondwaterkwaliteit - stikstofkringloop - nitraatuitspoeling - stikstofverliezen - landbouwbedrijven - bemesting - strategisch management - water quality - surface water quality - groundwater quality - nitrogen cycle - nitrate leaching - nitrogen losses - farms - fertilizer application - strategic management
    In 2008 the European Commission released a call for proposals under the workprogramme topic: novel approaches for reducing nitrogen losses. The objective of the programme was to improve uptake of the Nitrates Directive at the farm level. The consortium (Newcastle University, Louis Bolk Institute, Technical University of Madrid, and Aarhus University) responded to the call by developing a project that combined a review of the state of the art in technologies to reduce losses of N to water, with the upgrading of a user-friendly software package for simulating field-scale N dynamics, and the testing of strategies with farmers. N-Toolbox will lay the foundations for improved implementation of water protection policy at the farm level throughout the EU. This document is a short summary of key findings and experiences from the on-farm case study component of the project in Spain, United Kingdom, The Netherlands and Denmark.
    PlantyOrganic: design and results 2012
    Burgt, G.J.H.M. van der; Bus, M. - \ 2012
    Driebergen : Louis Bolk Instituut (Publicatie / Louis Bolk Instituut 2012-048 LbP) - 37 p.
    bemesting - biologische landbouw - akkerbouw - groenbemesters - teeltsystemen - stikstofkringloop - veldproeven - rotaties - fertilizer application - organic farming - arable farming - green manures - cropping systems - nitrogen cycle - field tests - rotations
    Increasingly strict legislation about fertilizer inputs and developing organic regulations are a strong stimulation to optimize the internal nutrient dynamics of organic arable farms. In the project ' PlantyOrganic', initialized by Biowad and realized at SPNA location Kollumerwaard, a challenging arable system is developed and tested: 100% internal nitrogen supply without input of nutrients from outside. In this report the design of the rotation and fertilizer scheme is presented and discussed, and the starting conditions in spring 2012 are documented. The NDICEA nitrogen model is used to explore the nitrogen dynamics. It is concluded that a 100% farm-own nitrogen supply can be achieved with good production levels. The 2012 results gave no reason to reconsider the rotation and fertilizer design, but since this was the first year of this experiment none of the crops had the pre-crop as foreseen in the design and the fertilizer used was only partly cut-and-carry fertilizer
    PlantyOrganic - Onderzoeksverslag 2012: Onderzoek naar het innovatieve landbousysteem dat zichzelf voorziet van (plantaardige) stikstof en daarmee 100% zelfvoorzienend is
    Burgt, G.J.H.M. van der; Werkman, D. ; Bus, M. - \ 2012
    Biowad - 35 p.
    akkerbouw - groenteteelt - veldgewassen - biologische landbouw - groenbemesters - bemesting - agrarische bedrijfsvoering - duurzaamheid (sustainability) - veldproeven - stikstofgehalte - stikstofkringloop - aardappelen - grasklaver - penen - bloemkolen - tarwe - arable farming - vegetable growing - field crops - organic farming - green manures - fertilizer application - farm management - sustainability - field tests - nitrogen content - nitrogen cycle - potatoes - grass-clover swards - carrots - cauliflowers - wheat
    Onderzoek naar het innovatieve landbouwsysteem dat zichzelf voorziet van (plantaardige) stikstof en daarmee 100% zelfvoorzienend is. In dit rapport worden alle projectactiviteiten in 2012 beschreven en komen de eerste resultaten aan de orde. Aangezien het een meerjarig project is – er wordt verwacht ten minste een volledige rotatie van zes jaar te kunnen onderzoeken – en in dit eerste jaar de meeste gewassen nog niet de voorvrucht hadden die ze in het ontwerp hebben, zijn de resultaten nog bescheiden.
    Explorative research on innovative nitrogen recovery
    Eekert, M.H.A. van; Weijma, J. ; Verdoes, N. ; Buisonje, F.E. de; Reitsma, B.A.H. ; Bulk, J. van den - \ 2012
    Amersfoort : Stichting Toegepast Onderzoek Waterbeheer (Rapport / STOWA 2012-51) - ISBN 9789057735851 - 56
    afvalwaterbehandeling - rioolwaterzuivering - zuiveringsinstallaties - stikstof - terugwinning - stikstofmeststoffen - stikstofkringloop - waste water treatment - sewage treatment - purification plants - nitrogen - recovery - nitrogen fertilizers - nitrogen cycle
    This report comprises the results of an explorative study on innovative nitrogen recovery from side streams of wastewater treatment plants (WWTPs) in the Netherlands. The main objective of the study was to identify promising new technologies for recovery of nitrogen which can be subsequently used as an artificial fertilizer. This shortcircuits the global nitrogen cycle and thereby reduces the environmental impact of the nitrogen cycle that has been distorted by human influence (eutrophication, greenhouse gases).
    Evaluation of the NDICEA model
    Rietberg, P.I. ; Burgt, G.J.H.M. van der - \ 2012
    Driebergen : Louis Bolk Institute (Publication 2012-026 LbP) - 39 p.
    bemesting - modellen - beslissingsmodellen - stikstof - stikstofmeststoffen - stikstofkringloop - voedingsstoffenbeschikbaarheid - fertilizer application - models - decision models - nitrogen - nitrogen fertilizers - nitrogen cycle - nutrient availability
    Within the N-Toolbox project the NDICEA nitrogen model, one of the key tools in the virtual Toolbox, has been improved and tested in England, Denmark and Spain. The model performance was evaluated on datasets from these three countries by means of visual observation, RMSE and RSR from the soil nitrogen dynamics. In England the scenarios with organic fertilizer performed better than those with artificial fertilizer, leading to the suggestion that the calculated nitrogen release out of fertilizer could be improved. Timing of the soil sampling on soil inorganic nitrogen is important to realize a good model evaluation; two samples only, before sowing and after harvest, is not enough. When soil mineral nitrogen samples were taken during crop growth, model calculation and measured values showed sometimes big differences. It is suggested to improve the plant nitrogen uptake sub-model.
    Nutrient flows in urban and peri-urban agroecosystems in three West African cities
    Abdulkadir, A. - \ 2012
    Wageningen University. Promotor(en): Herman van Keulen, co-promotor(en): J.O. Agbenin; Peter Leffelaar. - [S.l.] : s.n. - ISBN 9789461730039 - 217
    stikstofkringloop - kringlopen - voedingsstoffen - stadslandbouw - bedrijfssystemen - west-afrika - nitrogen cycle - cycling - nutrients - urban agriculture - farming systems - west africa

    Key words: Sustainability, CATPCA, two-step cluster analysis, farm types, nutrient balances, West Africa, gross margin, NUTMON/MONQI.

    Urban and peri-urban agriculture (UPA) is defined as the cultivation of crops and keeping livestock within and around cities. In addition to providing the cities’ demand of fresh vegetables, crops and livestock products, it plays an important role in the livelihoods of the urban farmers. With the rapid urbanization in sub-Saharan Africa, UPA provides food and jobs for many urban dwellers. UPA makes use of a diverse range of urban resources such as labour, waste and wastewater to produce food and raise livestock, and it is characterized by large nutrient imports into farms or gardens, often accompanied by environmental and human health risks. In view of the complexity and diversity of the UPA systems, there is a need to understand the socio-economic characteristics of UPA as drivers to farm management practices. This research was conducted in three secondary West African cities with important UPA activities: Kano (Nigeria), Bobo Dioulasso (Burkina Faso) and Sikasso (Mali). From principal component analysis of categorical variables (CATPCA) and two-step cluster analysis, six major farm types were identified based on production systems and market orientation, of which three are common in the three cities and one farm type is unique to each city. The six farm types are commercial gardening plus field crop-livestock (cGCL); commercial gardening plus semi-commercial cropping (cGscC); commercial livestock plus subsistence field cropping (cLsC); commercial gardening plus semi-commercial livestock (cGscL); commercial cropping (cC); and commercial gardening (cG). The former three are common for the three cities, the latter three farm types are unique for one city, each. The diverse activities in these farm types contributed differently to household income. Nutrient balance studies are useful indicators to assess the sustainability of farming systems. From the identified farm types, in-depth assessment of nutrient flows and balances as well as the economic performance of the different production systems was conducted in Kano (Nigeria) using the nutrient monitoring toolbox (NUTMON/MONQI). Farm nitrogen (N) balance was positive at 56.6, 67.4 and 56.4 kg farm−1 yr−1 for cGCL, cGscL and cLsC farm types, respectively. The same trend was observed for phosphorus (P) and potassium (K) in all the farm types except for cGCL where an annual negative K balance of 16 kg farm−1 was found. Commercially-oriented livestock keeping (cLsC) was economically more viable than the other farm types with average annual positive gross margin (GM) and net cash flow (NCF) of 033 and 35, respectively. Cropping activities within cGCL and cGscL had positive GMs (059 and 94) and NCFs (57 and 06), but livestock activities in both farm types incurred financial losses. Using the same MONQI approach across vegetable production systems of the three cities, large amounts of nutrients were observed to be applied with large positive nutrient balances. Average annual N balances were positive for all gardens in the three cities: 279, 1127 and 74 kg N ha–1 in Kano, Bobo Dioulassoand Sikasso, respectively. Phosphorus balance was positive in all cities except annual K deficits of 222 and 187 kg ha–1 in Kano and Sikasso, respectively. Efficiencies were 63%, 51% and 87% for N; with poor P use efficiencies due to excess application in all three cities. K efficiency of 85% was observed in Bobo Dioulassowhile in Kano and Sikasso’s gardens, it was 120% and 110% respectively, indicating K mining. The average annual gross margins/benefits from gardening indicate a higher return of .83 m–2 in Bobo Dioulasso and differs statistically (P<0.05) from returns obtained in Kano (conv2.info.92 m–2) and Sikasso (.37 m–2). Results show that UPA is an important economic livelihood strategy for urban and peri-urban farmers because of positive economic returns but with huge environmental trade-offs as a consequence of excess nutrient application. Efforts to better integrate resource management with measures to improve environmental and food safety are required of UPA stakeholders. Achieving this will require the formal recognition of the UPA sector by city officials, along with formulating realistic strategies for effective nutrient and water management for a more sustainable UPA operation in West Africa. The consistent and replicable typology developed in this study provides a basis to target system-specific technologies and appropriate recommendations to improve use efficiencies of resources as a whole.

    Denitrification in ditches, streams and shallow lakes
    Veraart, A.J. - \ 2012
    Wageningen University. Promotor(en): Marten Scheffer, co-promotor(en): Jeroen de Klein. - S.l. : s.n. - ISBN 9789461733115 - 208
    denitrificatie - sloten - meren - waterlopen - zoetwaterecologie - milieufactoren - stikstofkringloop - waterplanten - opwarming van de aarde - denitrification - ditches - lakes - streams - freshwater ecology - environmental factors - nitrogen cycle - aquatic plants - global warming
    Het Nederlandse oppervlaktewater wordt sterk belast met stikstof. Dit is afkomstig uit de landbouw, maar ook van industrie, verkeer en huishoudens. Door het teveel aan stikstof verslechtert de waterkwaliteit. In ondiepe meren leidt dit bijvoorbeeld tot overmatige algengroei met zuurstofloosheid en vissterfte tot gevolg. Denitrificatie, de omzetting van de stikstofverbinding nitraat naar stikstofgas, is een natuurlijk proces dat stikstof uit oppervlaktewater verwijdert.
    The nitrogen cycle and its influence on the European greenhouse gas balance
    Sutton, M.A. ; Nemitz, E. ; Skiba, U. ; Beier, C. ; Butterbach-Bahl, K. ; Cellier, P. ; Vries, W. de; Kros, J. ; Veldkamp, A. ; Reinds, G.J. - \ 2011
    Edinburgh : Centre for Ecology & Hydrology - ISBN 9781906698218 - 44
    klimaatverandering - broeikasgassen - stikstof - stikstofkringloop - europa - climatic change - greenhouse gases - nitrogen - nitrogen cycle - europe
    Newcomers in plant communities : interactions with soil and climate change
    Meisner, A. - \ 2011
    Wageningen University. Promotor(en): Wim van der Putten, co-promotor(en): W. de Boer. - [S.l.] : S.n. - ISBN 9789085859826 - 136
    plantengemeenschappen - invasieve soorten - stikstofkringloop - planten - klimaatverandering - bodem - geïntroduceerde soorten - stikstof - ecosystemen - interacties - plant communities - invasive species - nitrogen cycle - plants - climatic change - soil - introduced species - nitrogen - ecosystems - interactions

    Soil infertility undermines the agriculture-based livelihoods in Malawi, where it is blamed for poor crop yields and the creation of cycles of poverty. Although technologies and management strategies have been developed to reverse the decline in soil fertility, they are under-used by smallholder farmers. This study was conducted to assess with farmers the performance of a range of maize-legume technologies and their benefits on soil fertility management in central Malawi. Farmer participatory experimentation was a focus of the study. The aim was to facilitate learning and the interpretation of experiences, improve the communication of information about the concepts and technologies to farmers, and provide insights for researchers.

     Using a combination of survey and participatory methods, 136 smallholder farmers from Chisepo were grouped into four resource groups, comprising of better-resourced (RG 1 with 6 farmers), medium resourced (RG 2, 14 farmers), less well-resourced (RG 3, 64 farmers) and least-resourced groups (RG 4, 52 farmers). Analysing their livelihoods for their effects on soil fertility revealed that soil fertility management is a complex activity which is influenced by ownership of assets. Farmers from RG 1 and RG 2 owned more resources including cattle, had larger fields, hired-in labour for timely farm operations, earned more income and invested far more in soil fertility improvement. Farmers from RG 3 and 4 (who are in the large majority) were resource constrained and did not invest adequately in improving soil fertility. They had large food deficits due to poor crop yields. Ganyu labour (casual work done for other farmers for food or cash) was their main strategy to reduce food deficits. Farmers from all the four RGs were interested in working with research to explore strategies to improve soil fertility. They tested various grain- and green-manure-legumes, and mineral N and P fertiliser on maize and the legumes for effects on crop productivity and soil fertility. Associated production risk and interest in technology adoption were assessed.

     On-farm evaluation was done on maize (cv. MH18) in rotation with pigeonpea cv. ICP 9145,intercropped with groundnut (cv. CG 7), (Mz/Pp+Gn); intercropped with tephrosia (Mz+Tv); intercropped with pigeonpea (Mz+Pp) and in rotation with mucuna (Mz/Mp). These technologies were compared with sole crop maize without fertiliser (Mz−Ft) or with 35 kg N ha-1(Mz+Ft) in experiments with 32 farmers from the four RGs over four years. Economic and risk assessments were made. Maize grain yields (accumulated over the four years) were greater for farmers from RG 1 and 2 than RGs 3 and 4. Mz+Pp and Mz+Tv gave greater cumulative yields than Mz/Pp+Gn and Mz/Mp. The legumes improved maize grain yields by between 0.2 and 4 t ha-1(P < 0.001) over Mz-Ft and additionally they gave legume grain to the household.Mz+Pp was less risky to all RGs, and applying 35 kg N ha-1to the legumes resulted in Mz+Tv, Mz/Pp+Gn and Mz/Mp being least risky to RG 1, RG2 and RG 3. Farmers in RG 1 had the highest returns to labour (USconv2.info.8 day-1with Mz-Ft and US.1 day-1with Mz+Pp) and these increased to 1.9 and 1.7 respectively with 35 kg N ha-1. Mz+Pp intercrop gave consistent positive returns across the RGs and was the only technology to provide positive returns to labour in RG 4. Use of pigeonpea was overall the least risky option, and was especially suited to least-resourced farmers.

     Application of phosphorus fertiliser (0, 20 kg P ha-1) to legumes significantly (P = 0.05) increased grain and biomass yields for mucuna, groundnut, soyabean, Bambara groundnut and cowpea by 1.0, 0.8, 0.5, 1.0 and 0.3 t ha-1compared with unfertilised plots. Cowpea and fertilised groundnut had larger yields in the home fields than middle fields, but other legumes performed better (P = 0.05) in the middle fields.

     Maize responses to small amounts of fertiliser (0, 15, and 30 kg N ha-1and 0, 20 kg P ha-1) in two weeding regimes showed that weeding twice significantly (P < 0.001) raised maize yields by 0.4 t ha-1over weeding once (0.9 t ha-1). Stover yields (significant at P < 0.001) were 2.3 and 1.6 t ha-1respectively. Mean grain N kg ha-1was 17.1 and 9.8 for plots weeded twice and once respectively while that of stover were 10.1 and 5.6 kg N ha-1. Applying N at 15 kg N ha-1increased maize yields, but the 30 kg N ha-1increased yield only on more clay soils due to the effects of mid-season dry spells on sandy soils. Except for the physiological efficiency of N (PEN), all agronomic indices of N use showed significant differences due to weeding (agronomic efficiency of applied fertiliser N (AEN) at P < 0.001, recovery efficiency of applied N (REN) and partial factor productivity for N (PFPN) at P < 0.01). The average PENof 40.7and PFPNof 78.8 in plots weeded twice were within the ranges of 40–60 kg grain kg-1N and 40–80 kg grain kg-1N applied respectively. AENand REN values of 38.7 and 0.9 respectively were above the common range of 10-30 kg grain kg-1 N applied and 0.3-0.5 or 0.5–0.8 kg N kg-1. Mean indices from plots weeded just once were all within the ranges stated above but lower than indices from plots weeded twice; suggesting the unsustainability of the use of fertiliser without means to raise its efficiency through better management or combination with organic resources. Weeding twice gave higher returns to labour (USconv2.info.30 day-1) than weeding once (USconv2.info.05 day-1) and gross margins of US5.00 and US.00 with labour taken into account respectively.Farmers need to ensure timely weeding to get decent efficiencies and returns from the fertiliser, especially in drier cropping seasons.

     Using surveys, focus group discussions and the analytical hierarchy process (AHP), adoption of the ten legumes introduced to farmers in Chisepo was assessed among 136 farmers in 2004 and 84 farmers in 2007. Thirty-five percent of the farmers in 2004 and 22% in 2007 had adopted at least one of the legumes, with food grain legumes predominantly soyabean, groundnut, pigeonpea and to a lesser extent Bambara groundnut and cowpea being most adopted. Mucuna and tephrosia were adopted by few farmers while sunnhemp and grahamiana were not adopted at all. Farmers from RGs 1 and 2 adopted more of the legumes than those from RG 3 and 4. Lack of consistent markets, a lack of seed for planting, as well as land and labour shortages were cited for weak adoption.

     Soil fertility management by smallholder farmers is influenced by ownership of assets and the majority poorer farmers fail to invest adequately in improving soil fertility. In the absence of such resources, grain legumes will play an important role as a source of both food and organic matter to improve soil fertility. The participatory methods used in the study helped farmers better understand some of the soil fertility concepts and options, including the legumes. There is need to focus on how to assist farmers with practical knowledge to help them best combine organic and mineral fertiliser resources for improving soil fertility, and to develop and promote new dual-purpose legume options that feed humans and the soil.

     Key words: Adoption, analytical hierarchy process, crop yield, financial returns, food security, household assets, legume integration, livelihoods, NP fertiliser, nitrogen use efficiency, production risk, resource groups, smallholder, soil fertility, weeding. 

    Effecten van verzuring op bodemleven en stikstofstromen in bossen : verkenning van mogelijkheden voor herstelmaatregelen
    Kemmers, R.H. - \ 2011
    Wageningen : Alterra (Alterra-rapport 2204) - 42
    verzuring - bodemchemie - bodembiodiversiteit - bosgronden - stikstofbalans - stikstofkringloop - ecologisch herstel - acidification - soil chemistry - soil biodiversity - forest soils - nitrogen balance - nitrogen cycle - ecological restoration
    Dit rapport geeft een samenvatting van de resultaten van de analyses van het bodemleven, de stikstofstromen en bodemcondities over een brede range van bosgronden. In dit rapport staat de vraag centraal of door verzuring de relatie tussen ondergrondse en bovengrondse biodiversiteit via de N-kringloop is beinvloed. De conclusie is dat door verzuring de activiteit van bacterien (protozoa) en regenwormen is afgenomen en die van schimmels, nematoden en potwormen is toegenomen. Hierdoor is een verschuiving opgetreden in de stikstofbalans van N-immobilisatie naar netto N-mineralisatie. Hiervan profiteren opportunistische soorten in de ondergroei door het extra N-aanbod om te zetten in biomassa waardoor kritischer soorten worden benadeeld. Herstelmaatregelen moeten gericht zijn op herstel van de N-balans tussen bovengronds en ondergronds leven in de richting van een grotere N-retentie door het bodemleven. Hierin kan via het beheer worden gestuurd.
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

     
    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.