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.

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More food from fertile grounds: Integrating approaches in order to improve soil fertility
Beek, C.L. van; Duivenbooden, N. van; Noij, G.J. ; Heesmans, H.I.M. - \ 2014
Wageningen : Alterra
bodemvruchtbaarheid - teeltsystemen - bodemdegradatie - afrika ten zuiden van de sahara - mest - soil fertility - cropping systems - soil degradation - africa south of sahara - manures
Soils represent a major natural capital asset and have enormous potential to increase agricultural production while, at the same time, combating climate change and contributing to green economic growth. Yet, every year more than €3 thousand million is lost due to soil degradation. To unlock the potential of soils, nutrients need to be used more efficiently. This can be achieved by improving the recycling of nutrients, increasing organic matter content and applying fertilizers of the right type in the right amounts, at the right time and in the right place. There are several pathways of change that have been proposed to increase the productive capacity of soils. However, with current trends – globalization, urbanization, resource scarcity and climate change – new approaches are required. In our view, such approaches should be based on Integrated Soil Fertility Management (ISFM), which includes the application of both mineral fertilizers and organic manures. Subsequently, ISFM should be supplemented with site-specific interventions and a better match between supply and demand of (locally available) nutrients to make the best use of available resources, reduce environmental impacts and enhance green economic growth. The Fertile Grounds Initiative (FGI) was designed as an coordinated strategy of collaboration between actors in nutrient management at various spatial scales. It is based on eight subcomponents, which bring together the supply and demand of nutrients within a specific geographical area to make optimum use of site-specific interventions and available nutrients, supplemented with external imports. We expect the FGI to make a significant practical contribution to sustainable development in areas with limited soil fertility and nutrient availability, while at the same time resolving problems arising from nutrient excess in certain parts of the country and from (urban) waste streams, turning these into economic assets.
Exploring opportunities for diversification of specialized tobacco farms in the Northwest of Argentina
Chavez Clemente, M.D. - \ 2012
University. Promotor(en): Alfons Oude Lansink, co-promotor(en): Paul Berentsen. - S.l. : s.n. - ISBN 9789461734204 - 161
tabak - gespecialiseerde landbouw - gewasproductie - landbouwbedrijven - diversificatie - specialisatie - inkomen - risico - bodemdegradatie - argentinië - tobacco - specialized farming - crop production - farms - diversification - specialization - income - risk - soil degradation - argentina
In the Northwest of Argentina tobacco (Nicotiana tabacum L.) is economically and socially important. Tobacco mono-cropping, excessive tillage and inadequate irrigation management cause soil degradation. This and also tobacco production dependence on government subsidies and concern about health damage from tobacco consumption calls for research on diversification. The aim of this thesis was to explore opportunities for diversification of specialized tobacco farms in the Northwest of Argentina.
Risk assessment methodologies of soil threats in Europe: status and options for harmonization for risks by erosion, compaction, salinization, organic matter decline and landslides
Ano-Vidal, C. ; Ehlert, P.A.I. ; Hagyo, A. ; Heesmans, H.I.M. ; Kuikman, P.J. ; Oenema, O. ; Recatala-Boix, L. ; Simota, C. ; Tóth, G. ; Beek van, C. ; Akker van de, J. ; Zee, S.E.A.T.M. van der; Verzandvoort, S. - \ 2012
Luxembourg : Publications Office of the European Union (JCR scientific and technical reports ) - ISBN 9789279142918 - 84
risicoschatting - methodologie - bodemdegradatie - erosie - bodemverdichting - verzilting - organisch bodemmateriaal - aardverschuivingen - europa - risk assessment - methodology - soil degradation - erosion - soil compaction - salinization - soil organic matter - landslides - europe
The EU thematic strategy for soil protection recognizes that soil degradation through erosion, soil organic matter decline, compaction, salinization and landslides occurs in specific areas, and that these areas must be identified in an unequivocal way. Currently, there are various risk assessment methodologies (RAMs) and the question has risen to what extent these RAMs yield similar outcome and, if not, whether the outcome can be harmonized, i.e. whether the results of the various RAMs can be made compatible or comparable. In this study i) the current status of RAMs for erosion, soil organic matter decline, compaction, and salinization in the European Union (EU27) is reviewed, and ii) the need and the options for harmonization are assessed. The need for harmonization was defined as the likelihood of achieving different outcomes when using different RAMs, whereas the options for harmonization refer to the efforts that are required to harmonize soil RAMs. The current status of RAMSs in EU-27 was assessed on the basis of questionnaires, which were sent out to soil specialists and policy officers in all Member States. We received more than 100 (response rate >50%) completed questionnaires. It turned out that many of the so called RAMs are still incomplete; they are ‘process (or threat) quantifications’ rather than methodologies that assess the risk of a soil threat. Moreover, there were significant differences between RAMs for a soil threat in terms of (i) the notion of the threat, (ii) data collection, (iii) data processing, (iv) data interpretation, and (v) risk perception. The need for harmonization appeared highest for erosion and salinization, whereas the options for harmonization were best for SOM decline. Harmonization of soil RAMs may be very complex and for that reason not always feasible. We suggest two options that may facilitate unequivocal identification of risk (or priority) areas for soil threats, i) a two Tiered approach based on data availability and spatial scale and ii) generic harmonization, i.e. combining standardization and harmonization in a rather pragmatic way
Growing Sugarcane for Bioenergy – Effects on the Soil
Hartemink, A.E. - \ 2010
In: Proceedings 19th World Congress of Soil Science, Brisbane, Australia, 01 - 06 August, 2010. - - p. 13 - 15.
suikerriet - bodemdegradatie - verzuring - brandstofgewassen - uitspoelen - verliezen uit de bodem - verontreiniging - biobased economy - sugarcane - soil degradation - acidification - fuel crops - leaching - losses from soil - pollution
An increasing area of sugarcane is being growing for the production of bioenergy. Sugarcane puts a high demands on the soil due to the use of heavy machinery and because large amounts of nutrients are removed with the harvest. Biocides and inorganic fertilizers introduces risks of groundwater contamination, eutrophication of surface waters, soil pollution and acidification. This paper reviews the effect of commercial sugarcane production on soil chemical, physical and biological properties using data from the main producing areas. Although variation is considerable, soil organic C decreased in most soils under sugarcane and, also, soil acidification is common as a result of the use of N fertilizers. Increased bulk densities, lower water infiltration rates and lower aggregate stability occur in mechanized systems. There is some evidence for high leaching losses of fertilizer nutrients as well as herbicides and pesticides. Eutrophication of surface waters occurs in high-input systems. Sugarcane cultivation can substantially contribute to the supply of renewable energy, but that improved crop husbandry and precision farming principles are needed to sustain and improve the resource base on which production depends.
Soil use and management
Hartemink, A.E. ; McBratney, A.B. ; White, R.E. - \ 2009
London [etc.] : Earthscan (Earthscan reference collections ) - ISBN 9781844076468 - 328
bodemkunde - bodembeheer - bodemdegradatie - bodemvruchtbaarheid - soil science - soil management - soil degradation - soil fertility
This four-volume set, edited by leading experts in soil science, brings together in one collection a series of papers that have been fundamental to the development of soil science as a defined discipline. Volume 3 on Soil Use and Management covers: - Soil evaluation and land use planning - Soil and water conservation - Soil fertility and plant nutrition - Soil engineering and technology - Soil degradation control, remediation and reclamation
Organic and conservation agriculture, the best of both worlds?
Sukkel, W. - \ 2008
In: ECOMIT: Proceedings of the 5th International Scientific Conference on Sustainable Farming Systems, Piestany, Slovakia, 5-7 November 2008. - Piestany : Slovak Association for Sustainable Agriculture - ISBN 9788096960316 - p. 14 - 16.
klimaatverandering - bodemdegradatie - biologische landbouw - organische stof - brandstofgewassen - koolstofvastlegging in de bodem - biobased economy - climatic change - soil degradation - organic farming - organic matter - fuel crops - soil carbon sequestration
In millions of years huge amounts of organic matter were stored in the soil as organic matter or fossil energy carriers as oil, gas and coal. We make use of these stocks to supply us with energy and to be able to grow plants for our needs. However what has been stored in our soils for millions of years we now are depleting in a few hundred years. The amount of organic matter we return back to the soil is in general too low to maintain its capacity for plant production on the long term. Various studies show there is a decrease of organic matter in arable soils all over the world.
Boomkwekerij en aardkunde in Nederland
Maas, G.J. ; Reuler, H. van - \ 2008
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 113) - 32
boomkwekerijen - landbouwsector - landgebruik - bodemdegradatie - landschap - geomorfologie - forest nurseries - agricultural sector - land use - soil degradation - landscape - geomorphology
In opdracht van het Planbureau voor de Leefomgeving (PBL) is een verkennend onderzoek uitgevoerd naar het effect van de sector boomkwekerij op de kwaliteiten van het landschap die samenhangen met het reliëf en de bodem. De vraag in dit onderzoek is of er teeltmethoden in de boomkwekerij worden gehanteerd die een grotere impact hebben op bodem en reliëf dan algemeen landbouwkundig gebruik en die leiden tot het beschadigen of verdwijnen van aardkundige kwaliteiten, met name het reliëf.
The relation between geometry, hydrology and stability of complex hillslopes examined using low-dimensional hydrological models
Talebi, A. - \ 2008
University. Promotor(en): P.A. Troch; Remko Uijlenhoet. - [S.l.] : S.n. - ISBN 9789085047889 - 120
landdegradatie - bodemdegradatie - heuvels - hellingen - topografie - stabiliteit - hydrologie - meetkunde - wiskundige modellen - land degradation - soil degradation - hill land - slopes - topography - stability - hydrology - geometry - mathematical models
Key words: Hillslope geometry, Hillslope hydrology, Hillslope stability, Complex hillslopes, Modeling shallow landslides, HSB model, HSB-SM model.

The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsaturated interaction that usually leads to a water table rise. An increase of saturated groundwater flow can act as the triggering mechanism for slope failure. To account for the three-dimensional hillslope shape in which the groundwater flow and storage processes take place, simple (low-dimensional) but physically realistic models that represent hydrological processes at the hillslope scales are needed for reliable simulation of hillslope stability at the landscape scale. In this thesis the focus is on investigating the relation between hillslope geometry, hillslope hydrology and slope stability in complex hillslopes and hollows.
Several models have been presented in this thesis which examine the stability of nine characteristic hillslope types (landform elements) with three different profile curvatures (concave, straight and convex) and three different plan shapes (convergent, parallel and divergent). In addition to testing our models for nine characteristic hillslope types, a general relationship between plan shape and profile curvature of landform elements and the factor of safety is derived for a predefined hillslope length scale. Our results show that slope stability increases when profile curvature changes from concave to convex. In terms of plan shapes, changing from convergent to divergent, slope stability increases for all length profiles. Our analyses also show that the minimum safety factor occurs when the rate of subsurface flow is maximum. In fact, by increasing the subsurface flow, stability decreases for all hillslope shapes. Moreover, after a certain period of rainfall, the convergent hillslopes with concave and straight profiles become unstable faster than others whilst divergent convex hillslopes remain stable (even after intense rainfall). We also demonstrate that in hillslopes with non-constant soil depth (possible deep landslides), the ones with convex profiles and convergent plan shapes have slip surfaces with the minimum safety factor near the outlet region. Finally, we demonstrate that, in addition to bedrock slope, hillslope shape as represented by plan shape and profile curvature is an important control on hillslope stability.
With respect to the relation between rainfall occurrence and slope instability, a probabilistic model of rainfall-induced shallow landslides in complex hollows is also presented to investigate the relation between return period of rainfall, deposit thickness and landslide occurrence. A long term analysis of shallow landslides by the presented model illustrates that all hollows show a quite different behavior from the stability view point. Finally, we conclude that incorporating a more realistic description of hollow hydrology (the hillslope-storage Boussinesq model instead of the kinematic wave model) in landslide probability models is necessary, especially for hollows with a high convergence degree, which are more susceptible to landsliding. This model helps to theoretically investigate the relationship between return period of rainfall and landslide occurrence related to soil production (deposit thickness) in complex hollows.
In summary this thesis aims to understand theoretically how hydrological processes (subsurface flow and water table dynamics) affect slope stability in complex hillslopes and hollows. The presented models can widely be applied in many investigations of hillslope stability analysis because of their relative simplicity (low-dimensional).
Trendanalyse grondgebruik
Molendijk, L.P.G. ; Wolf, P.L. de; Breukers, M.L.H. - \ 2007
bodem - bodembescherming - bodemdegradatie - landgebruik - landbouwontwikkeling - landbouwbeleid - bodemkwaliteit - vergelijkend onderzoek - fytosanitair beleid - soil - soil conservation - soil degradation - land use - agricultural development - agricultural policy - soil quality - comparative research - phytosanitary policies
Toenemende wisselingen van gebruikers van grondpercelen (huurder, pachter) kunnen ertoe leiden dat er minder aandacht is voor bodemgezondheid. Daardoor bestaat het risico dat de basiskwaliteit van de Nederlandse percelen verslechtert. Dit staat haaks op het belang van de Nederlandse landbouw om zich een goede uitgangspositie in de vrije markt te verwerven door zich vooral toe te leggen op de teelt van uitgangsmateriaal met een hoge toegevoegde waard
Effecten van biomassaketens op landgebruik en bodemkwaliteit in Nederland : ontwikkeling van een toetsingskader
Hanegraaf, M.C. ; Molenaar, S.W. ; Elbersen, H.W. ; Annevelink, E. - \ 2007
Wageningen [etc.] : Nutriënten Management Instituut (Rapport / Nutri├½nten Management Instituut NMI 1183) - 56
landgebruik - duurzaamheid (sustainability) - biomassa - biomassa productie - bodemdegradatie - organisch bodemmateriaal - milieubeheer - bio-energie - bescherming - nederland - bodemkwaliteit - biobased economy - land use - sustainability - biomass - biomass production - soil degradation - soil organic matter - environmental management - bioenergy - protection - netherlands - soil quality
In opdracht van TCB (Technische Commissie Bodembescherming) heeft NMI een onderzoek uitgevoerd naar de mogelijke positieve en negatieve effecten van bio-energie op de bodemchemie.
Ecology of tree roots in substrates of The Hague
Arhipova, L. ; Spijker, J.H. ; Kopinga, J. - \ 2007
Wageningen : Alterra (Alterra-rapport 1590) - 111
wortels - straatbomen - stedelijke gebieden - groeimedia - rizosfeer - substraten - bodemdegradatie - kationenuitwisselingcapaciteit - waterafstotende gronden - hydrofobiciteit - nederland - zuid-holland - roots - street trees - urban areas - growing media - rhizosphere - substrates - soil degradation - cation exchange capacity - water repellent soils - hydrophobicity - netherlands
The ecology of uniformly and non-uniformly distributed roots in layered and/or heterogeneous substrates, especially sand-peat-clay mixes, have been studied from literature and through a case study. There is a strong interaction between soil layering and/or heterogeneity and local root growth and local branching rate. In principle, the minimum area of root surface that a plant needs is very low. Real situations have much higher root surface areas for several reasons, one being the absence of synchronisation and synlocation of supply and demand of nutrients and water
Practice makes perfect: participatory innovation in soil fertility management to improve rural livelihoods in East Africa
Jager, A. de - \ 2007
University. Promotor(en): Herman van Keulen; Ken Giller; Cees Leeuwis. - [S.l.] : S.n. - ISBN 9789085048428 - 218
bodemvruchtbaarheid - voedingsstoffenbalans - kringlopen - bodemdegradatie - bedrijfssystemenonderzoek - kleine landbouwbedrijven - boeren - oost-afrika - soil fertility - nutrient balance - cycling - soil degradation - farming systems research - small farms - farmers - east africa
Keywords: soil nutrient balances, soil fertility degradation, East Africa , participatory innovation, experiential learning, farmer field schools, smallholder agriculture

Maintaining and improving soil fertility is crucial for Africa to attain the Millennium Development Goals. Fertile soil and balanced soil nutrient management are major foundations for sustainable food production, contribute to a sound management of natural resources and assist in controlling environmental degradation such as erosion, loss of biodiversity, pollution of water sources and acidification. This thesis describes the development of an inter-disciplinary diagnostic tool to assess impacts of farm management practices on nutrient balances and the use of the tool in participative research and innovation approaches in East Africa over a ten-year period from 1995 to 2005.

The structured conceptual framework and related NUTMON approach facilitate a comprehensive description and analysis of management practices in complex smallholder farming systems. The approach has been successfully applied in a variety of projects addressing soil fertility degradation in Africa and Asia . A wide audience from both the research and development communities have been exposed to the approach. The integration of biophysical, financial and livelihood aspects in the analyses proved essential to assist effective decision making by farm households. The quantitative analysis based on farmers’ own data and observations, complements other participative tools and contributed to learning and innovation processes within households.

The various projects which implemented the approach showed that negative soil nutrient balances and high incidence of poverty prevail in most of the farming systems in East Africa . However, huge variations between geographical areas and individual farms were observed. Farmers often successfully integrated technical innovations in existing farm management systems, whereby combinations of application of organic manure and fertilizers appeared to be the most effective strategy. The research has shown that, once smallholders are equipped with knowledge and the capacity to learn, are empowered in organizations and connected to markets and the private sector, they can substantially improve their rural livelihoods. Therefore a focus on participatory experiential learning approaches and farmer organizations that result in new arrangements in innovation systems needs to be mainstreamed in rural development projects. Experiences show that the sustainability of group learning processes increases considerably when the groups engage successfully in commercial activities at the same time.
Innovations in soil fertility management were most successful and had the greatest impact on livelihoods in areas with both high agricultural potential and access to large urban markets. Investments in soil management or other technologies can be realised more easily by smallholders when they have opportunities to generate cash through commercial sales and value-addition, or when they have access to non-farm income. In more marginal areas most investments in inputs and technologies were financially unattractive or risky. In these areas priority needs be given to creating a more conducive environment for smallholders to do business and explore alternatives to food crop production.

Achteruitgang van nutriëntengehalten in voedselgewassen door een verminderde bodemkwaliteit?
Rietra, R.P.J.J. - \ 2007
Wageningen : Alterra (Alterra-rapport 1439) - 47
bodem - bodemdegradatie - bodemvruchtbaarheid - voedingsstoffen - voedselproducten - voedselkwaliteit - voedselsamenstelling - soil - soil degradation - soil fertility - nutrients - food products - food quality - food composition
Er bestaat maatschappelijke zorg over een mogelijke achteruitgang van het gehalte aan nutriënten in voedsel. De achteruitgang wordt regelmatig toegeschreven aan een verminderde kwaliteit van landbouwgronden. Deze bureaustudie geeft een overzicht over de vraag of er achteruitgang is van de voedselkwaliteit en of die veroorzaakt wordt door een achteruitgang van de bodemkwaliteit of andere factoren
Soil erosion and nitrogen leaching in northern Vietnam: expression and modelling
Trinh Van Mai, - \ 2007
University. Promotor(en): Herman van Keulen, co-promotor(en): R.P. Rötter; Rudi Hessel. - [S.l.] : S.n. - ISBN 9789085046059 - 182 p.
erosie - bodem - uitspoelen - stikstof - experimenten - modellen - bodemdegradatie - remote sensing - waterbalans - rijst - vietnam - erosion - soil - leaching - nitrogen - experiments - models - soil degradation - water balance - rice
Wind erosion control with scattered vegetation in the Sahelian zone of Burkina Faso
Leenders, J.K. - \ 2006
University. Promotor(en): Leo Stroosnijder, co-promotor(en): Geert Sterk; J.H. van Boxel. - [S.l. ] : S.n. - ISBN 9085044006 - 170 p.
winderosie - erosiebestrijding - bouwland - vegetatie - windsnelheid - bodemdegradatie - simulatiemodellen - sahel - burkina faso - wind erosion - erosion control - arable land - vegetation - wind speed - soil degradation - simulation models
Organische stof verdient meer aandacht : rekenmodel op internet geeft inzicht in uw eigen situatie
Dekking, A.J.G. - \ 2004
Ekoland 23 (2004)12. - ISSN 0926-9142 - p. 18 - 19.
biologische landbouw - organische stof - organisch bodemmateriaal - bodemvruchtbaarheid - organische meststoffen - plantenvoeding - bedrijfssystemen - bedrijfssystemenonderzoek - rotaties - bodemonderzoek - bodemeigenschappen - bodemdegradatie - degradatie - landbouwkundig onderzoek - bemesting - organic farming - organic matter - soil organic matter - soil fertility - organic fertilizers - plant nutrition - farming systems - farming systems research - rotations - soil testing - soil properties - soil degradation - degradation - agricultural research - fertilizer application
In het langjarige bedrijfssystemenonderzoek op Vredepeel (zandgrond) en het OBS Nagele (kleigrond) is gebleken dat de afbraaksnelheid van organische stof in de bodem in biologische bedrijfssystemen hoger ligt dan de 2 procent die tot nu toe werd aangenomen. Het verloop van het organische-stofgehalte in de bodem laat een afbraak zien van 2,5 procent, wat duidelijk hoger is dan in gangbare systemen. Uit een berekening van de aanvoer van effectieve organische stof (EOS) uit gewasresten, groenbemesters en mest, en de benodigde EOS-aanvoer bij een afbraak van 2,5 procent, blijkt dat het tekort in EOS-aanvoer ongeveer 1000 kg per hectare bedraagt
Sustainable soil fertility management in Benin: learning from farmers
Saïdou, A. ; Kuyper, T.W. ; Kossou, D.K. ; Tossou, R. ; Richards, P. - \ 2004
NJAS Wageningen Journal of Life Sciences 52 (2004)3-4. - ISSN 1573-5214 - p. 349 - 369.
bodemvruchtbaarheid - bodemdegradatie - inheemse kennis - benin - soil fertility - soil degradation - indigenous knowledge
The perception of farmers from the Atacora and Savè regions of Benin was studied about the causes and consequences of land degradation and corrective actions for sustaining soil fertility. Research methods in this diagnostic study included group discussions, using non-standardized unstructured interviews and participant observations. Farmland degradation leading to declining yields, and land tenure arrangements were identified as the main constraints on the sustainability of agriculture. In both regions the farmers stated that climatic changes (less and more irregular rainfall), run off, erosion, and overexploitation of farmlands caused land degradation. Soil fertility status was assessed on the basis of dicotyledonous weeds, soil texture and colour, and soil fauna (earthworm casting activity). Farmers have adapted their cropping systems to the local environment by developing traditional and new strategies and activities that could contribute to maintain or enhance crop productivity. These strategies include animal manure, inorganic fertilizer, crop rotation, a five-year fallow, extensive cropping systems with cassava or egusi melon, and emigration. Land tenure arrangements between landlords and migrants affect strategies that can be applied to maintain soil fertility. The importance of building mutual trust and the need to experiment with different land tenure arrangements are indicated. A framework for interactive research where knowledge is collectively generated is proposed in order to test the effectiveness and applicability of some of these local innovations not yet well understood by conventional science.
Soil quality improvement for crop production in semi-arid West Africa
Ouédraogo, E. - \ 2004
Wageningen : Wageningen University and Research Centre (Tropical resource management papers 51) - ISBN 9067547328 - 193
bodemvruchtbaarheid - bodemdegradatie - bodembescherming - grondbewerking - gewasproductie - semi-aride gronden - semi-aride klimaatzones - west-afrika - bodemkwaliteit - soil fertility - soil degradation - soil conservation - tillage - crop production - semiarid soils - semiarid zones - west africa - soil quality
Soil quality improvement for crop production in semi-arid West Africa
Ouédraogo, E. - \ 2004
University. Promotor(en): Leo Stroosnijder, co-promotor(en): Lijbert Brussaard. - Wageningen : Wageningen Universiteit - ISBN 9058089924 - 193 p.
bodemvruchtbaarheid - bodemdegradatie - bodembescherming - grondbewerking - gewasproductie - semi-aride gronden - semi-aride klimaatzones - west-afrika - bodemkwaliteit - soil fertility - soil degradation - soil conservation - tillage - crop production - semiarid soils - semiarid zones - west africa - soil quality
Soil quality maintenance and crop production improvement in semi-arid West Africa require appropriate cropping technologies, which are ecologically sound and economically viable. Thus, on-farm and on-station experiments have been carried out on the central plateau and in the south of Burkina Faso The results show that adoption of improved soil fertility technologies such as composting by farmers is determined by soil fertility status, access to the market and social reasons. Organic amendments increase crop production but its effects on soil carbon depend on its quality. Soil tillage improves crop performance as a result of enhanced crop nutrient uptake and water use efficiency but decrease soil carbon with fertilisation. Combination of crop residues and urea may reverse this negative effect. Soil fauna accounted for 50 % of crop production. Termites mediated the disappearance of low-quality organic amendments. Soil carbon build-up in the presence of soil fauna requires the use of easily decomposable organic material or combined low quality organic material with nitrogen fertiliser. Phosphate rock-derived phosphorus availability is 4 times higher in earthworm casts than in surrounding soil. Single use of nitrogen fertiliser leads to low use efficiency by crop and induces low to negative economic benefit. Combination of organic resource and fertiliser significantly increases crop performance and economic benefit of N fertilisers. Without both organic and mineral external inputs, soil quality maintenance and crop production improvement cannot be achieved at the same time in semi-arid West-Africa. Improving soil quality and crop performance in semi-arid West-Africa is best achieved with an integrated soil fertility management including external inputs (organic and mineral), the contribution of soil fauna and soil and water conservation measures and in some cases with tillage
Beslissen over vrij grondverzet op basis van Bayesiaanse toets op oppervlaktefractie ernstig verontreinigde grond
Brus, D.J. - \ 2004
Wageningen : Alterra (Alterra rapport 867) - 39
bodemverontreiniging - bodemdegradatie - bodemeigenschappen - bodemchemie - bodemonderzoek - analyse van besluiten - ruimtelijke variatie - bayesiaanse theorie - bodemkwaliteit - grondverzet - soil pollution - soil degradation - soil properties - soil chemistry - soil testing - decision analysis - spatial variation - bayesian theory - soil quality - earth moving
De vrijstellingsregeling grondverzet biedt de mogelijkheid tot vrijstelling van partijkeuringen wanneer aangetoond wordt dat de oppervlaktefractie ernstig verontreinigde grond kleiner is dan 5%. In dit onderzoek wordt de beslissing gebaseerd op een statistische toets omdat dan rekening wordt gehouden met het aantal monsters dat in sterke mate de mate van onzekerheid over de oppervlaktefractie bepaald. Bayesiaans toetsen biedt interessante mogelijkheden in vergelijking met klassiek toetsen omdat, gegeven het aantal monsters en het aantal ernstig verontreinigde monsters in de steekproef, de betrouwbaarheid van de conclusie `oppervlaktefractie <0.05¿ door het gebruik van de a priori verdeling over de oppervlaktefractie toeneemt. Ook het verlies van foute beslissingen (schade tengevolge van als bodem hergebruikte ernstig verontreinigde partij grond, en kosten van keuren van niet ernstig verontreinigde partijen) kan hierdoor gereduceerd worden.
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