Sustainable use of phosphorus : EU tender ENV.B1/ETU/2009/0025
Schroder, J.J. ; Cordell, D. ; Smit, A.L. ; Rosemarin, A. - \ 2010
Wageningen : Plant Research International (Report / Plant Research International 357) - 122
fosfor - kringlopen - duurzaamheid (sustainability) - verarming - verliezen - natuurfosfaat - gebruiksefficiëntie - landbouwbeleid - europese unie - phosphorus - cycling - sustainability - depletion - losses - rock phosphate - use efficiency - agricultural policy - european union
As sustainable phosphorus use will sooner or later become essential for global food security, action is needed. As far as the required actions are concerned, the report has identified short-term and long-term policy options which could improve the current level of phosphorus use efficiency in agriculture. The report emphasizes, however, that policies should not be developed in isolation, let alone for agriculture only, but that all parts of the chain, that is primary production, processing and consumption, should be addressed in an integrative way. The current reliance on imported rock-based phosphorus (‘3 kg P per European citizen per year’) can not be continued in the long run. To become truly sustainable, phosphorus use efficiency must approach a level close to 100% in each chain. Therefore, a full recycling of phosphorus will become a condition sine qua non for global and European food security. The urgency of policies and measures needed for that will be determined by the phosphate rock reserves considered exploitable (including geopolitically and legally accessible), the prevention of accumulation and losses, the size of the global population and its preferences in terms of food, feed, fibers and fuels, and its appreciation of biodiversity. This will require drastic adjustments to the way we manage agriculture, and it may also require adjustments to our society as a whole, including the processing of our ‘wastes’.
Phosphorus in agriculture: global resoources, trends and developments : report to the Steering Committee Technology Assessment of the Ministery of Agriculture, Nature and Food Quality, The Netherlands, and in collaboration with the Nutrient Flow Task Group (NFTG), supported by DPRN (Development Policy review Network)
Smit, A.L. ; Bindraban, P.S. ; Schröder, J.J. ; Conijn, J.G. ; Meer, H.G. van der - \ 2009
Wageningen : Plant Research International (Report / Plant Research International 282) - 36
gewasproductie - bodemvruchtbaarheid - fosfor - kringlopen - hulpbronnenbehoud - verarming - wereld - agro-ecosystemen - schaarste - crop production - soil fertility - phosphorus - cycling - resource conservation - depletion - world - agroecosystems - scarcity
In agroproduction systems recycling of phosphorus should be the general principle. This holds for manure, crop residues and other organic rest products. Especially the cattle feedlot industry can be a market for DGGS, being a co-product of the distillery industries. Recovery from seawater is a possible alternative for the re-use of phosphorus. These and other aspects are reviewed in this inventory on a world scale
Time dependence in jamming and unjamming
Parker, A. - \ 2009
Wageningen University. Promotor(en): Erik van der Linden. - [S.l. : S.n. - ISBN 9789085853879 - 99
gels - stabiliteit - dynamica - reologie - verouderen - sedimentatie - thixotropie - verarming - uitvlokking - xanthan - gelatine - evenwicht - gels - stability - dynamics - rheology - aging - sedimentation - thixotropy - depletion - flocculation - xanthan - gelatin - equilibrium
Three different food systems have been studied: emulsion/polymer mixtures, gelatin gels and carrageenan gels. Typically, samples are trapped, or jammed, far from equilibrium. The simple jamming paradigm suggests that, once in the jammed state, these systems are static. This useful approximation is often too simple, since these systems frequently evolve in time. Their evolution has been measured systematically. Where possible, these results have been placed in the context of the physics of out-of-equilibrium systems.
The emulsion/polymer mixtures are a model for salad dressing. The emulsions alone are colloidally stable, but become inhomogeneous, due to the effects of gravity. With sufficient polymer, they can be apparently stable (jammed) for months, but then quite suddenly start to sediment – the system unjams. The kinetics of this delayed sedimentation is measured as a function of the key parameters. A new model is proposed for the mechanism by which polymers stabilize emulsions.
Solutions of gelatin form gels when cooled, due to the formation of portions of helix. A new model relating the amount of helix to the elasticity is described. The gels always evolve slowly. At steady state, the rate of evolution of the elasticity is constant in log(time), so this system conforms to Struick’s physical aging scenario. The effect of temperature changes on the evolution of gels is extremely complex. The results show that there is a deep analogy between this behavior and that of spin glasses, which are exotic magnetic phases.
Gels of iota carrageenan, a seaweed polysaccharide, have unique rheological properties: they regel almost instantly after strong mixing. This property is used in the dairy industry, but has not been studied previously. The kinetics of recovery after shear has been measured for water gels and milk gels.
Fosfaat: sleutelfactor bij natuurontwikkeling op voormalige landbouwgronden?
Sival, F.P. ; Chardon, W.J. - \ 2003
Vakblad Natuurbeheer (2003)1. - ISSN 1388-4875 - p. 10 - 11.
natuurbescherming - landgebruik - landbouwgrond - fosfaat - fosfaten - bodem - bodemchemie - bodemeigenschappen - voedingsstoffenovermaat - mineraalovermaat - voedingsstoffenbeschikbaarheid - verarming - vegetatie - vegetatiebeheer - bodembeheer - natuur - natuurtechniek - nature conservation - land use - agricultural land - phosphate - phosphates - soil - soil chemistry - soil properties - nutrient excesses - mineral excess - nutrient availability - depletion - vegetation - vegetation management - soil management - nature - ecological engineering
Bij de realisering van de ecologische hoofdstructuur en bij de reconstructie van gebieden met intensieve veehouderij komt veel landbouwgrond vrij voor natuurontwikkeling. De bodems hiervan zijn vaak rijk aan voedingstoffen door langdurige bemesting en zijn verdroogd door ontwatering. Verschralende maatregelen vinden vaak plaats om condities te creëren voor voedselarme vegetatie. Maar helaas zijn de pogingen vaak zonder succes
A participatory agroforestry approach for soil and water conservation in Ethiopia
Bekele - Tesemma, A. - \ 1997
Agricultural University. Promotor(en): L. Stroosnijder; A. van Maaren. - Wageningen : Landbouwuniversiteit - ISBN 9789054857631 - 229
erosiebestrijding - waterbescherming - bodembescherming - bodem - erosie - bodemuitputting - verarming - participatie - bosbouw - agroforestry - ethiopië - erosion control - water conservation - soil conservation - soil - erosion - soil exhaustion - depletion - participation - forestry - agroforestry - ethiopia
The rates of soil erosion and land degradation in Ethiopia are frighteningly high. Crop production, livestock keeping and energy supply situations are at risk. The highlands are the most affected. Past rehabilitation efforts have been immense. Much labour, capital and trained staff have been mobilized to correct the situation, but the outcome has not been encouraging. There are a number of reasons for the failure. Methodical and technological problems are evident. Exclusion of farmers and their indigenous knowledge at all levels of planning and implementation, the use of uniform and 'foreign' soil conservation and reforestation technologies, mistrust between farmers and facilitators, farmers' bias to production over conservation, miss-use of food-for-work programmes in conservation works, lack of conducive land tenure and tree usufruct have all contributed.
Each of the six sub-processes of the approach are constructed and tested under Tikurso catchment conditions. In the process, the researching steps that were initially conceptualized in their abstract form are transformed into more illustrated sub-processes. As a result, an agroforestry approach whose nested sub-processes are connected to form a multi-loop approach is evolved. The constructed approach assumes that circumstances change in either the social sector or the enviromnental setting or both through time. For generation and usage of this expectedly new information, the approach has three alternate avenues. Choice among the alternative avenues is made depending on the knowledge-gap identified during the evaluation and feedback sub-process of the approach. The results from land sustaining quality, cost-benefit analysis and adaptability tests confirm that the approach has significant benefits to soil and water conservation.
Modelling the effect of grazing on infiltration, runoff and primary production in the Sahel.
Stroosnijder, L. - \ 1996
Ecological Modelling 92 (1996)1. - ISSN 0304-3800 - p. 79 - 88.
verarming - begrazing - hydraulisch geleidingsvermogen - infiltratie - modellen - onderzoek - sahel - kwel - bodemuitputting - depletion - grazing - hydraulic conductivity - infiltration - models - research - sahel - seepage - soil exhaustion
Rural people's response to soil fertility decline : the Adja case (Benin)
Brouwers, J.H.A.M. - \ 1993
Agricultural University. Promotor(en): N.G. Röling, co-promotor(en): D.P. Gibbon. - S.l. : Brouwers - ISBN 9789067543224 - 157
bodemuitputting - verarming - erosiebestrijding - waterbescherming - bodembescherming - sociologie - plattelandsgemeenschappen - benin - bemesting - soil exhaustion - depletion - erosion control - water conservation - soil conservation - sociology - rural communities - benin - fertilizer application
This study examines rural people's knowledge in changing conditions such as decreasing soil fertility and increasing population. It explores how farmers, who depend on rainfed agriculture and are confronted with an ever increasing population, react. The study presents the case of an ethnic group, the Adja, who live in South-West Benin (West Africa).
Chapter I looks at agriculture in tropical rainfed areas experiencing a decline in soil fertility. Research and extension have so far generated few feasible technical solutions to the problem. This chapter explores how rural people themselves cope with the situation. Rural people's knowledge processes still seem to be poorly understood. This study investigates how the Adja farmers perceive demographic pressure and how they react to it, what knowledge influences them and what learning processes have resulted in their knowledge.
The second chapter provides a theoretical perspective relevant to this study. An analysis of the relationship between researcher and rural people is given, as well as a systems perspective on rural people's knowledge, a conceptualisation of rural people's knowledge and related concepts. Rural people's knowledge will be viewed as the reconstruction of knowledge by both rural people and the researcher through a dialogical process. In addition, the reconstruction can only indicate this knowledge at a given moment in time. Three levels of studies on rural people's knowledge are distinguished: (1) knowledge 'products', (2) the social construction of rural people's knowledge, and (3) the activities which resulted in their knowledge.
Chapter 3 presents the methodology used in this work. Special attention is given to methodological issues related to research on rural people's knowledge and the role of the researcher.
In Chapter 4, a general introduction to the Adja plateau and its inhabitants is presented. Besides an agronomic point of view, also the Adja classification point of view is given for basic elements of the environment. The agro-ecological conditions on the plateau, the socio-cultural organisation of the Adja, as well as the history of the plateau and the interventions to change it, are described. The complexity of Adja farming is one response to the risks involved in farming. The Adja use several elements from their environment to plan agricultural activities. The history of Adja farming shows constant changes in agricultural practices, giving a dynamic picture. Agronomic interventions designed to tackle the declining soil fertility problem have been limited in their results.
The Adja oil palm-based agro-forestry system broadly relieves problems imposed by increasing population pressure and is outlined and analysed in Chapter 5. The system produces significant quantities of biomass and at the same time the oil palm is firmly entrenched in Adja agricultural activities. Also a view on soil fertility as seen by the Adja themselves is described, together with an analysis of the effect of the oil palm system on soil fertility. The Adja recognise and appreciate the importance of soil life and organic matter, a viewpoint which is corroborated by the soil analysis.
In Chapter 6, a presentation is given of phenomena related to rural people's knowledge on the Adja plateau, connected with variable demographic pressure and soil fertility. Oil palm densities are higher in the more populated areas. When the oil palm system comes under pressure, farmers try to prolong the cultivation of annuals, increasing the pruning of oil palms and felling them sooner. Intensification and increasing diversification of agricultural production takes place in the more populated areas. In addition, such areas have developed more dynamic and diverse aspects of social life (e.g. religion, off-farm work, migration, trade, legislation) compared to areas with more land per caput. Leadership conventions have a broader base, than in earlier days. In addition to older people, enterprising or educated young people, women and men are included in decision-making. The emergence of women as agricultural entrepreneurs, with considerable trading freedom, and who buy small pieces of land hiring more labourers than male farmers, is partly explained by male out-migration and ongoing individualisation of the Adja society.
In order to understand why farmers act the way they do, one must try to proceed from their knowledge, values and ideas. Elaborating on earlier chapters dealing with Adja knowledge, Chapter 7 seeks to understand the Adja perspective by examining Adja 'sense making' activities, like learning, transformation of technology, classifying and theory making. Various examples show that Adja learning has its roots in action. In the daily practice of this learning, constant attention to possible improvement is evident. Results of experiments are shared, interpreted and discussed only in a restricted group. Encounters between different experimenting groups take place in specific social and physical contexts. Externally generated technologies are transformed and combined with social, economic, political and other factors to become an integral part of agriculture. The variability amongst Adja farmers argues in favour of the capacity to assess at an individual or experimenting-group level the potential value of a new method or technique. In the more highly populated areas, this feature of new relationships and networks result in a dynamic cultural identity.
In the final chapter, it is concluded that Adja farmers have a rich body of knowledge related to agriculture. However, their agricultural knowledge is strongly related to other phenomena (e.g. religion, social struggles and diversity, access to resources, migration). In addition, it is not static, but in a continuous process of change. It is also concluded that researchers may be able to sustain ongoing Adja experiments by elaborating on a broader set of methodologies for interactive and shared learning. The adaptive research performances of farmers might be enhanced by researchers who visit farmers in their fields and try to join in their discussion. The ability of researchers to enlarge their discursive analysis by incorporating a view of practical activities as applied by farmers seems an important prerequisite for fruitful collaboration. In addition, adaptive performances of farmers might be understood and discussed by researchers if they are willing to acknowledge dimensions other than agriculture.
Bodemgesteldheid, vruchtwisseling en bodemziekten
Smet, L.A.H. de - \ 1973
Wageningen : STIBOKA (Interne mededeling / Stichting voor Bodemkartering 12) - 19
verarming - rotaties - bodemuitputting - bodemvruchtbaarheid - bodemgeschiktheid - depletion - rotations - soil exhaustion - soil fertility - soil suitability
Kalkverliezen op zandbouwland
Loman, H. ; Willigen, P. de - \ 1972
Haren (Gr.) : I.B. (Rapport / Instituut voor Bodemvruchtbaarheid 1972, no. 13) - 42
calcium - verarming - uitspoelen - zandgronden - bodem - bodemuitputting - calcium - depletion - leaching - sandy soils - soil - soil exhaustion
Het ter beschikking komen van kali in sterk uitputtenden grond
Paauw, F. van der - \ 1942
's-Gravenhage : [s.n.] (Verslagen van landbouwkundige onderzoekingen no. 48,5) - 44
verarming - kalium - bodem - bodemuitputting - depletion - potassium - soil - soil exhaustion