Skip to main content

Advertisement

SpringerLink
Log in

Beyond adding up inputs and outputs: process assessment and upscaling in modelling nutrient flows

  • Published:
Nutrient Cycling in Agroecosystems Aims and scope Submit manuscript

Abstract

Departing from the historical background of scientific interest in soil fertility and sustainable agricultural production in sub-Saharan Africa, a review is conducted of nutrient budget studies carried out in semi-arid West Africa at scales ranging from individual fields to the sub-continent. For both, nitrogen and phosphorus, the comparison discloses largely diverging balances calculated for similar agro-ecosystems. In a first step, the modes of calculation of the nutrient budgets are examined. It is demonstrated that the calculations used in the different studies differ by the variables and biophysical processes taken into account, and by the choice of spatial scales as well as related time scales. One important discrepancy between approaches is whether and to which extent nutrient flows are internalized when upscaling. The extent to which the impact of individual and communal management, especially of pastoral and forestry resources, on nutrient flows is accounted for is a second cause of divergence. Moreover, it was observed that nutrient budgets tend to be increasingly negative as the spatial scale of the study increases from farm to sub-continent. This unexpected trend is traced back to the lack of internalization of nutrient flows when upscaling. The complexity of the scale patterns of nutrient flows and that of the interactions and the tradeoffs in the effects of management calls for the use of models to calculate nutrient budgets. Therefore, in a second step, examples of a static model, a multiple-goal linear programming model and a decision rules model were reviewed, all of which include the calculation of nutrient flows and balances and which were applied to West-African farming systems. The models are analyzed for their way of dealing with the critical issues of spatial and temporal scales and the impact of resource management on nutrient flows, taking into account that they have different objectives and were designed for different spatio-temporal scales. To conclude, suggestions were made for strengthening the use of models as tools enabling ex-ante testing of alternative agricultural technologies and policies that could improve soil nutrient balances in semi-arid sub-Saharan Africa.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Achard F. and Banoin M. 2003. Fallows, forage production and nutrient transfers by livestock in Niger. Nutr. Cycl. Agroecosyst. 65: 183-189.

    Google Scholar 

  • Anderson J.M. and Ingram J.S.I. 1989. Tropical Soil Biology and Fertility: A Handbook of Methods. CAB International, Walling-ford, UK.

  • Aubréville A. 1949. Climats, forêts et désertification de l'Afrique tropicale Vol. 1, 381 pp. Société d'Editions Géographiques, Maritimes et Coloniales, Paris, France.

    Google Scholar 

  • Ayantunde A.A., Fernández-Rivera S., Hiernaux P.H.Y., Van Keulen H., Udo H.M.J. and Chanono M. 2001. Effect of timing and duration of grazing of growing cattle in the West African Sahel on diet selection, fecal output, eating time, forage intake and live-weight changes. Anim. Sci. 72: 117-128.

    Google Scholar 

  • Bacyé B., Moreau R. and Feller C. 1998. Décomposition d'une poudrette de fumier incorporée dans un sol sableux de versant et un sol argilo-limoneux de bas-fond en milieu soudano-sahélien. Etude et Gestion des Sols 5: 83-92.

    Google Scholar 

  • Barreteau O., Bousquet F., Millier C. and Weber J. 2004. Suitabil-ity of Multi-Agent Simulations to study irrigated system viability: application to case studies in the Senegal River Valley. Agr. Syst. 80: 255-275.

    Google Scholar 

  • Bationo A., Buerkert A., Sedogo M.P., Christianson B.C. and Mokwunye A.U. 1995. A critical review of crop residue use as soil amendment in the West African semi-arid tropics. In: Pow-ell J.M., Fernández-Rivera S., Williams T.O. and Renard C. (eds), Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of Sub-Saharan Africa, Vol. 2, pp. 305-322.

  • International Livestock Center for Africa, Addis Ababa, Ethio-pia. Bationo A. and Buerkert A. 2001. Soil organic carbon management for sustainable land use in Sudano-Sahelian West-Africa. Nutr. Cycl. Agroecosyst. 61: 131-142.

    Google Scholar 

  • Becu N., Perez P., Walker A., Barreteau O. and Page C.L. 2003. Agent based simulation of a small catchment water management in northern Thailand-description of the CATCHSCAPE model. Ecol. Model. 170: 319-331.

    Google Scholar 

  • Bonham-Carter G.F. 1994. Geographic Information Systems for Geoscientists: Modelling with GIS. Elsevier Science Ltd, Kidlington, UK.

    Google Scholar 

  • Boone R.B., Coughenour M.B., Galvin K.A. and Ellis J.A. 2002. Addressing management questions for Ngorongoro Conservation Area, Tanzania, using the Savanna modelling system. Afr. J. Ecol. 40: 138-150.

    Google Scholar 

  • Breman H. 1990. No sustainability without external inputs. Africa Seminar, Maastricht, pp. 124-134. Ministry of Foreign Affairs, Directorate General for International Cooperation, Project Group Africa, The Hague, The Netherlands.

    Google Scholar 

  • Breman H. and De Wit C.T. 1983. Rangeland productivity and ex-ploitation in the Sahel. Science 221: 1341-1347.

    Google Scholar 

  • Breman H., Groot J.J.R. and Van Keulen H. 2001. Resource limi-tations in Sahelian agriculture. Global Environment Change: Human and Policy Dimensions 11: 59-68.

    Google Scholar 

  • Buerkert A. and Hiernaux P. 1998. Nutrients in the West African Soudano-Sahelian zone: losses, transfers and role of external in-puts. Z. Pflanzenernähr Bodenkd. 161: 365-383.

    Google Scholar 

  • Buerkert A. and Lamers J.P.A. 1999. Soil erosion and deposition effects on surface characteristics and pearl millet growth in the West African Sahel. Plant Soil 215: 239-253.

    Google Scholar 

  • Busqué J. 2002. Nutrient states and dynamics of low input farming systems in Western Niger. ILRI Report of Consultancy, 19 pp. International Livestock Research Institute, Niamey, Niger.

    Google Scholar 

  • Chevalier A. 1900. Les zones et les provinces botaniques de l'Afrique occidentale français. Comptes Rendues Hebdomadaire des Séances de l'Académie des Sciences, Paris, 130: 1205-1208.

    Google Scholar 

  • De Gironcourt G. 1912. Le sommet de la Boucle du Niger: Géographie, Physique et Botanique. La Géographie 25: 153-172.

    Google Scholar 

  • De Jager A., Nandwa S.M. and Okoth P.F. 1998. Monitoring nu-trient flows and economic performance in African farming sys-tem (UTMO) I. Concepts and methodologies. Agr. Ecosyst. Environ 71: 37-48.

    Google Scholar 

  • De Leeuw P.N., Diarra L. and Hiernaux P. 1993. An analysis of feed demand and supply for pastoral livestock in the Gourma re-gion of Mali. In: Behnke Jr. R.H., Scoones I. and Kerven C. (eds), Range Ecology at Disequilibrium. New Models of Natu-ral Variability and Pastoral Adaptation in African Savannas, pp. 136-152. Overseas Development Institute, London, UK.

    Google Scholar 

  • De Ridder N. and Van Keulen H. 1990. Some aspects of the role of organic matter in sustainable intensified arable farming sys-tems in the West-African semi-arid-tropics (A). Fert. Res. 26: 299-310.

    Google Scholar 

  • Dembélé F., Masse D. and Yossi H. 1998. Rôle des feux de brousse sur la dynamique des adventices et sur la qualité des sols au cours des premières années de jachère, dans les régions soudani-ennes du Mali. In: Floret C. and Pontanier R. (eds), Jachères et Maintien de la Fertilité, pp. 33-40. IER Bamako, Mali and Or-stom, France.

    Google Scholar 

  • Dent J.B., Edwards-Jones G. and McGregor M.J. 1995. Simulation of ecological, social and economic factors in agricultural systems. Agr. Syst. 49: 337-351.

    Google Scholar 

  • Desconnets J.C., Taupin J.D., Lebel T. and Leduc C. 1997. Hydrology of the HAPEX-Sahel Central Super-site: surface wa-ter drainage and aquifer recharge through the pool systems. J. Hydrol. 188/189: 155-178.

    Google Scholar 

  • Dijkstra J. and France J. 1995. Modelling and methodology in ani-mal science. In: Danfær A. and Lescoat P. (eds), Proceedings of the 4 th International Workshop on Modelling Nutrient Utilization in Farm Animals, pp. 9-18. National Institute of Animal Science, Foulum, Denmark.

    Google Scholar 

  • Dugué P. 1998. Les transferts de fertilité dus à l'élevage en zone de savane. Agr. Dévelop. 18: 99-107.

    Google Scholar 

  • Esse P.C., Buerkert A., Hiernaux P. and Assa A. 2001. Decompo-sition of and nutrient release from ruminant manure on acid sandy soils in the Sahelian zone of Niger, West Africa. Agr. Ecosyst. Environ. 83: 55-63.

    Google Scholar 

  • Estèves M. and Lapetite J.M. 2003. A multi-scale approach of run-off generation in a Sahelain gully catchment: a case study in Ni-ger. Catena 50: 255-271.

    Google Scholar 

  • Evéquoz M. and Yadji G. 1998. Conservation et gestion des eaux et des sols au Niger. Durabilité du système de production agri-cole nord-sahélien. Report, Eidgennössische Technische Hoch-schule, Zurich, Switzerland.

  • Feller C. 1993. Organic inputs, soil organic matter and functional soil organic compartments in low-activity clay soils in tropical zones. In: Mulongoy K. and Merckx R. (eds), Soil Organic Mat-ter Dynamics and Sustainability of Tropical Agriculture, pp. 77-88. John Wiley and Sons, Chichester, UK.

    Google Scholar 

  • Feller C. and Beare M.H. 1997. Physical control of soil organic matter dynamics in the tropics. Geoderma 79: 69-116.

    Google Scholar 

  • Feller C. and Milleville P. 1977. Evolution des sols de défriche ré-cente dans la région des terres neuves (énégal orienta).1 ère partie: Présentation de l'etude et evolution des principes caractéristiques morphologiques et physico-chimiques. Cahiers ORSTOM, Série Biologie 12 (3): 199-211.

    Google Scholar 

  • Ferber J. 1995. Les systèmes multi-agents: vers une intelligence collective. Inter Editions, Paris, France.150

  • Feuillette S., Bousquet F. and Le Goulven P. 2003. SINUSE: a multi-agent model to negotiate water demand management on a free access water table. Environ. Modell. Softw. 18: 413-427.

    Google Scholar 

  • Folmer E.C.R., Geurts P.M.H. and Francisco J.R. 1998. Assessment of soil fertility depletion in Mozambique. Agr. Ecosyst. Environ. 71: 159-167.

    Google Scholar 

  • France J. and Thornley J.H.M. 1984. Mathematical Models in Ag-riculture. Butterworths, London, UK.

    Google Scholar 

  • Fuhrmann S., Kosubek K.H., Mittring P. and Streit U. 1999. En-twicklung von GIS-Werkzeugen für die Regionalisierung. In: Kleeberg H.B., Mauser W., Peschke G. and Streit U. (eds), Hy-drologie und Regionalisierung. DFG-Forschungsbericht, pp. 371-389. Wiley-VCH, Weinheim, Germany.

    Google Scholar 

  • Gérard B., Hiernaux P., Muehlig-Versen B. and Buerkert A. 2001. Destructive and non-destructive measurements of residual crop residue and phosphorus effects on growth and composition of herbaceous fallow species in the Sahel. Plant Soil 228: 265-273.

    Google Scholar 

  • Grouzis M. 1988. Structure, productivité, et dynamique des systèmes écologiques Sahéliens (are d'Oursi, Burkina Fas), Collection Etudes et Thèses. Editions de l'ORSTOM, Paris, France.

  • Harris F.M.A. 1998. Farm-level assessment of nutrient balance in northern Nigeria. Agr. Ecosyst. Environ. 71: 201-214.

    Google Scholar 

  • Harris F.M.A. 2002. Management of manure in farming systems in semi-arid West Africa. Expl. Agric. 38: 131-148.

    Google Scholar 

  • Hengsdijk H. and Kruseman G. 1992. Operationalizing the DLV program: an integrated agro-economic and agro-ecological ap-proach to a methodology for analysis of sustainable land use and regional agricultural policy. Report 1, DLV-DLO. Wageningen, The Netherlands.

    Google Scholar 

  • Herrmann S. 2001. Entscheidungsunterstützung in der Land-nutzungsplanung mittels GIS-gestützter Modellierung. Maßstab-sbezug, Realitätsnähe und Praxisrelevanz. Der Andere Verlag, Osnabrück, Germany.

    Google Scholar 

  • Hiernaux P., Fernández-Rivera S., Schlecht E., Turner M.D. and Williams T.O. 1998. Livestock mediated nutrient transfers in Sahelian agro-ecosystems. In: Renard G., Neef A., Becker K. and von Oppen M. (eds), Fertility Management in West Af-rican Land Use Systems, pp. 339-348. Margraf Verlag, Weikers-heim, Germany.

    Google Scholar 

  • Hoffmann I., Gerling D., Kyiogwom U.B. and Mané-Bielfeldt A. 2001. Farmers' management strategies to maintain soil fertility in a remote area in northwest Nigeria. Agric. Ecosyst. Environ. 86: 263-275.

    Google Scholar 

  • Huhtanen P. and Kukkonen U. 1995. Comparison of methods, markers, sampling sites and models for estimating digesta pas-sage kinetics in cattle fed at two levels of intake. Anim. Feed. Sci. Technol. 52: 141-158.

    Google Scholar 

  • Jones B. 1938. Desiccation and the West African Colonies. Geogr. J. 91: 4-23.

    Google Scholar 

  • Kanté S. 2001. Gestion de la fertilité des sols par classe d'exploitation au Mali-Sud. Tropical Resource Management Pa-pers, Wageningen University and Research Centre, The Nether-lands.

    Google Scholar 

  • Karambiri H., Ribolzi O., Delhoume J.P., Ducloux J., Coudrain-Ribstein A. and Casenave A. 2003. Importance of soil surface characteristics on water erosion in a small grazed Sahelian catchment. Hydrol. Process. 17: 1495-1507.

    Google Scholar 

  • Keating B.A., Carberry P.S., Hammer G.L., Probert M.E., Robert-son M.J., Holzworth D., Huth N.I., Hargreaves J.N.G., Meinke H., Hochman Z., McLean G., Verburg K., Snow V., Dimes J.P., Silburn M., Wang E., Brown S., Bristow K.L., Asseng S., Chap-man S., McCown R.L., Freebairn D.M. and Smith C.J. 2003. An overview of APSIM, a model designed for farming systems simulation. Eur. J. Agron. 18: 267-288.

    Google Scholar 

  • Krogh L. 1997. Field and village nutrient balances in millet culti-vation in northern Burkina Faso: a village case study. J. Arid Environ. 35: 147-159.

    Google Scholar 

  • Kruseman G. 2000. Bio-economic modelling for agricultural intensification. Ph.D. Thesis, University of Wageningen, The Netherlands.

    Google Scholar 

  • La Rovere R. 2001. Livestock Roles and Agro-Environmental Sus-tainability of Sahelian Niger mixed Crop-Livestock Systems un-der Intensification. Ph.D. Thesis, University of Bologna, Italy.

    Google Scholar 

  • Lamprey H. 1975. Report on the desert encroachment reconnais-sance in northern Sudan. 21 October to 11 November, 1975. Re-printed in Desert. Control Bull. 17 (1988): 1-7.

    Google Scholar 

  • Landais E. and Lhoste P. 1990. L'association agriculture-élevage en Afrique intertropicale: un mythe techniciste confronté aux réalités au terrain. Cah. Sci. Hum. 26: 217-235.

    Google Scholar 

  • Ledant J.P. 1984. La réduction de biomasse végétale en Afrique de l'Ouest. Première partie: aperçu général. Les Annales de Gem-bloux 90: 195-216.

    Google Scholar 

  • Manlay R.J. 2000. Organic Matter Dynamics in Mixed-Farming Systems of the West African Savanna: a Village Case Study from South Senegal. Ph.D. Thesis, ENGREF, Paris, France.

  • Manlay R.J., Ickowicz A., Masse D., Feller C. and Richard D. 2004. Spatial carbon, nitrogen and phosphorus budget in a vil-lage of the West African savanna. II. Element flows and func-tioning of a mixed farming system. Agr. Syst. 79: 83-107.

    Google Scholar 

  • Michels K., Sivakumar M.V.K. and Allison B.E. 1995. Wind ero-sion control using crop residue I. Effects on soil flux and soil properties. Field Crops Res. 40: 101-110.

    Google Scholar 

  • Osbahr H. and Allan C. 2003. Indigenous knowledge of soil fertil-ity management in southwest Niger. Geoderma 111: 457-479.

    Google Scholar 

  • Penning de Vries F.W.T. and Djitèye M.A. 1982. La Productivité des Pâturages Sahéliens. Une Étude des Sols, des Végétations et de l'Exploitation de cette Ressource Naturelle. Agric. Res. Rep. 918. Pudoc, Wageningen, The Netherlands.

    Google Scholar 

  • Peugeot C., Cappelare B., Vieux B.E., Séguis L. and Maia A. 2003. Hydrologic process simulation of a semiarid, endoreic catchment in Sahelian West Niger. 1. Model-aided data analysis and screening. J. Hydrol. 279: 224-243.

    Google Scholar 

  • Powell J.M., Fernández-Rivera S., Hiernaux P. and Turner M.D. 1996. Nutrient cycling in integrated rangeland/cropland systems of the Sahel. Agr. Syst. 52: 143-170.

    Google Scholar 

  • Powell J.M. and Ikpe F. 1992. Fertilizer factories. Nutrient recy-cling through livestock. ILEIA Newslett. 8(3): 13-14.

    Google Scholar 

  • Powell J.M., Ikpe F.N. and Somda Z.C. 1999. Crop yield and the fate of nitrogen and phosphorus following application of plant material and feces to soil. Nutr. Cycl. Agroecosyst. 54: 215-226.

    Google Scholar 

  • Powell J.M. and Mohamed-Saleem M.A. 1987. Nitrogen and phosphorus transfers in a crop-livestock system in West Africa. Agr. Syst. 25: 261-277.

    Google Scholar 

  • Rajot J.L. 2001. Wind blown sediment mass budget of Sahelian village land units in Niger. B. Soc. Geol. Fr. 172: 523-531.

    Google Scholar 

  • Rath T. 1999. Nutrition and Productivity of Milking Cattle on a semi-arid Rangeland in West Africa. Ph.D. Thesis, University of Hohenheim. Verlag Grauer, Beuren-Stuttgart, Germany.

    Google Scholar 

  • Ramisch J. 1999. In the balance? Evaluating soil nutrient budgets for an agro-pastoral village of southern Mali. Series: Managing Africa's Soils, Issue. 9. 28 pp. IIED, London, UK.

    Google Scholar 

  • Reardon T., Kelly V., Diagana B., Dione J., Crawford E., Savadogo K. and Boughton D. 1998. L'intensification durable induite par le facteur capital dans l'agriculture sahélienne: surmonter les contraintes structurelles après les reformes des politiques macro-économiques. In: Breman H. and Sissoko K. (eds), L'intensification agricole au Sahel, pp. 807-822. Editions Karthala, Paris, France.

    Google Scholar 

  • Renard C., Boudouresque E., Schmelzer G. and Bationo A. 1993. Evolution de la végétation dans une zone protégée du Sahel (a-doré, Nige). ICRISAT, Niamey, Niger. In: Floret C. and Serpantié G. (eds), La jachère en Afrique de l'Ouest, pp. 297-306. ORSTOM, Collection Colloques et Séminaires, Paris, France.

    Google Scholar 

  • Saidou A., Janssen B.H. and Temminghoff E.J.M. 2003. Effects of soil properties, mulch and NPK fertilizer on maize yields and nutrient budgets on ferralitic soils in southern Benin. Agr. Eco-syst. Environ. 100: 265-273.

    Google Scholar 

  • Schlecht E. and Buerkert A. 2004. Organic inputs and farmers' management strategies in millet fields of western Niger. Geoderma 121: 271-289.

    Google Scholar 

  • Schlecht E., Fernández-Rivera S. and Hiernaux P. 1998. Timing, size and N-concentration of faecal and urinary excretions in cattle, sheep and goats-can they be used for better manuring of cropland? In: Renard G., Neef A., Becker K. and von Oppen M. (eds), Soil Fertility Management in West African Land Use Sys-tems, pp. 361-368. Margraf Verlag, Weikersheim, Germany.

    Google Scholar 

  • Schlecht E., Hiernaux P., Achard F. and Turner M.D. 2004. Live-stock related nutrient budgets within village territories in west-ern Niger. Nutr. Cycl. Agroecosyst. 68: 199-211.

    Google Scholar 

  • Schlecht E., Kadaouré I. and Becker K. 2003. Moving across vil-lage landscapes: Seasonal changes of grazing orbits of cattle, sheep and goats in the Sahel. Trop. Subtrop. Agroecosyst. 3: 427-431.

    Google Scholar 

  • Schlecht E., Sangaré M. and Becker K. 1999. Supplementation of Zebu cattle grazing Sahelian pastures. I. Diet selection and feed intake. J. Agric. Sci. Camb. 133: 69-81.

    Google Scholar 

  • Scoones I. and Toulmin C. 1998. Soil nutrient budgets and balances: what use for policy? Agric. Ecosyst. Environ. 71: 255-269.

    Google Scholar 

  • Shepherd K.D. and Soule M.J. 1998. Soil fertility management in west Kenya: dynamic simulation of productivity, profitability and sustainability at different resource endowment levels. Agric. Ecosyst. Environ. 71: 131-145.

    Google Scholar 

  • Sissoko K. 1998. Et demain l'Agriculture? Options Techniques et Mesures Politiques pour un Développement Agricole durable en Afrique Subsaharienne: Cas du Cercle de Koutiala en Zone Sud du Mali. Ph.D. Thesis, University of Wageningen, The Nether-lands.

    Google Scholar 

  • Smaling E.M.A., Fresco L.O. and De Jager A. 1996. Classifying, monitoring and improving soil nutrient stocks and flows in Af-rican agriculture. Ambio 25: 492-496.

    Google Scholar 

  • Smaling E.M.A., Stoorvogel J.J. and Windmaijer P.N. 1993. Cal-culating soil nutrient balances in Africa at different scales. II. District scale. Fert. Res. 35: 237-250.

    Google Scholar 

  • Somda Z.C., Powell J.M., Fernández-Rivera S. and Reed J. 1995. Feed factors affecting nutrient excretion by ruminants and the fate of nutrients when applied to soil. In: Powell J.M., Fernán-dez-Rivera S., Williams T.O. and Renard C. (eds), Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of sub-Saharan Africa Vol. 2, pp. 227-243. International Livestock Center for Africa, Addis Ababa, Ethiopia.

    Google Scholar 

  • Stahr K. and Herrmann L. 1996. Origin, deposition, and composi-tion of dust, and consequences for soil and site properties with special reference to the semi-arid regions of West Africa. In: Buerkert B., Allison B.E. and von Oppen M. (eds), Wind Ero-sion in Niger. Implications and Control Measures in a Millet-Based Farming System, pp. 45-65. Developments in Plant and Soil Sciences 67. Kluwer, Dordrecht, The Netherlands.

    Google Scholar 

  • Stebbing E.P. 1935. The encroaching Sahara: the threat to the West African colonies. Geogr. J. 85: 506-524.

    Google Scholar 

  • Sterk G., Herrmann L. and Bationo A. 1996. Wind-blown nutrient transport and soil productivity changes in southwest Niger. Land Degrad. Dev. 7: 325-335.

    Google Scholar 

  • Stevenson F.J. and Cole M.A. 1999. The internal cycle of nitrogen in soil. In: Stevenson F.J. and Cole M.A. (eds), Cycles of Soils: Carbon, Nitrogen, Phosphorus, Sulfur, Micronutrients. 2 nd Edi-tion. John Wiley and Sons, New York, USA, pp. 191-229.

    Google Scholar 

  • Stoorvogel J.J., Schipper R.A. and Jansen D.M. 1995. USTED: a methodology for a quantitative analysis of land use scenarios. Neth. J. Agric. Sci. 43: 5-18.

    Google Scholar 

  • Stoorvogel J.J. and Smaling E.M.A. 1990. Assessment of soil nu-trient depletion in sub-Saharan Africa: 1983-2000. Main Report, Vol 1. The Winand Staring Centre, Wageningen, The Nether-lands.

    Google Scholar 

  • Stoorvogel J.J., Smaling E.M.A. and Janssen B.H. 1993. Calculat-ing soil nutrient balances in Africa at different scales. I. Supra-national scale. Fert. Res. 35: 227-335.

    Google Scholar 

  • Struif Bontkes T. 1999. Modelling Dynamics of Agricultural De-velopment: a Process Approach-the Case of Koutiala (al). Ph.D. Thesis, University of Wageningen, The Netherlands.

    Google Scholar 

  • Stuth J., Hamilton W. and Conner R. 2002. Insights in develop-ment and deployment of the GLA and NUTBAL Decision Sup-port Systems for grazinglands. Agric. Syst. 74: 99-113.

    Google Scholar 

  • Thebaud B. 1999. Gestion de L'espace et Crise Pastorale au Sahel; Étude Comparative du Niger Oriental et du Yagha Burkinabé. Ph.D. Thesis, EHESS, Paris, France.

    Google Scholar 

  • Toulmin C. 1986. Access to food, dry season strategies and house-hold size amongst the Bambara of Central Mali. IDS Bull. 17: 58-66.

    Google Scholar 

  • Turner M.D. 1995. The sustainability of rangeland to cropland nu-trient transfer in semi-arid West Africa: ecological and social di-mensions neglected in the debate. In: Powell J.M., Fernández-Rivera S., Williams T.O. and Renard C. (eds), Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of Sub-Saharan Africa, Vol. 2, pp. 435-452. International Livestock Center for Africa, Addis Ababa, Ethiopia.

    Google Scholar 

  • Turner M.D. 1998. Long term effects of daily grazing orbits on nu-trient availability in Sahelian West Africa: 1. Gradients in the chemical composition of rangeland soils and vegetation. J. Bio-geogr. 25: 669-682.

    Google Scholar 

  • Turner M.D. and Williams T.O. 2002. Livestock market dynamics and local vulnerabilities in the Sahel. World Dev. 30: 683-705.

    Google Scholar 

  • Turner M.D., Hiernaux P. and Schlecht E. 2004. The effect of grazing management on the forage offered village-based livestock in semi-arid West Africa. Ecosystems (accepted).

  • Van den Bosch H., De Jager A. and Vlaming J. 1998. Monitoring nutrient flows and economic performance in African farming systems (UTMO) II. Tool development. Agric. Ecosyst. En-viron. 71: 49-62.

    Google Scholar 

  • Van der Pol F. 1992. Soil mining. Royal Tropical Institute (I), Bulletin 325. Amsterdam, The Netherlands.

    Google Scholar 

  • Williams T.O., Powell J.M. and Fernández-Rivera S. 1995. Manure availability in relation to sustainable food crop production in Semi-Arid West Africa: evidence from Niger. Quarterly J. Int. Agr. 34: 248-258.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Institute for Animal Production in the Tropics and Subtropics, Germany

    Eva Schlecht

  2. Centre for Agriculture in the Tropics and Subtropics, University of Hohenheim, D-70593 Stuttgart, Germany

    Pierre Hiernaux

Authors
  1. Eva Schlecht
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Pierre Hiernaux
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Schlecht, E., Hiernaux, P. Beyond adding up inputs and outputs: process assessment and upscaling in modelling nutrient flows. Nutrient Cycling in Agroecosystems 70, 303–319 (2004). https://doi.org/10.1007/s10705-004-0765-2

Download citation

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10705-004-0765-2

Search

Navigation