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Browsing by Author "van Keulen, H."

Now showing 1 - 4 of 4
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    Co-evolutionary scenarios of intensification and privatization of resource use in rural communities of south-western Niger
    Rovere, R.; Hiernaux, P.; van Keulen, H.; Schiere, J.; Szonyi, J. (Amsterdam, Netherlands: Elsevier Science B.V., 2005)
    Agricultural production in the semi-arid agro-ecosystems of the Sahel centres on cereal staple crops and pastoralism with increasing crop-livestock integration. Animals mobilize soil fertility through manure production, graze crop by-products, and transfer nutrients from distant pastures to cropped areas. Yet in these systems various interacting factors, i.e. climate variability, poor soil fertility, poverty, and institutional constraints limit the capacity of agriculture to keep pace with the growing needs of an increasing human population.
  • Food from Dry Lands: An Integrated Approach to Planning of Agricultural Development
    Alberda, T.; van Keulen, H.; Seligman, N. G.; de Wit, C. T. (Dordrecht, Netherlands; Boston, MA: Kluwer Academic Publishers, 1992)
    The book centers on an analysis of the options for the agronomic development of semiarid regions with winter rains (i.e. Mediterranean regions). Data obtained in the northern Negev desert in Israel serve as a starting point. On the basis of these data, crop and sheep husbandry systems were designed and integrated into agro-pastoral systems in which small-grain crops act as a buffer for feed production. These systems served as a basis for rational planning of regional agricultural development under alternative development objectives. In analyzing the possibilities, a three-step approach was developed: first the feasibility and robustness of selected innovative techniques at the farm level were investigated in relation to variability in weather and prices, then a matrix of production techniques for a region was formulated in terms of their physical inputs and outputs, and finally, this matrix was embedded into a dynamic multiple-goal linear programming model. In comparing the results for different goals, the consequences for goal achievement and desired production techniques can be made explicit, and in this way the book can be a guide for actual development planning in semiarid regions.
  • Resource limitations in Sahelian agriculture
    Breman, H.; Groot, J. J.; van Keulen, H. (2001)
    In general, Africa has poor soils and unfavorable climates for agriculture. This is specially so in the Sahel of West Africa. Moreover, poor infrastructure means that fertilizer prices are higher in the Sahel than in Europe. Sahelian farmers have few incentives to maintain, let alone improve output. Nonetheless, the results of field experiments show that there are methods by which they could do this, in particular, by improving soil organic matter status, since this is often the principal way in which N, P and K are held in the soil. In the general absence of good policies to encourage fertility improvement, the Lomé workshop set goals for national fertilizer plans.
  • Système de production agriculture-élevage du Mali-Sud: De la carte des flux de l'exploitation à l'outil d'aide à la décision en passant par le modèle
    Kanté, S.; van Keulen, H.; Smaling, E. (2004)
    Dans la zone soudano-sahélienne, beaucoup d'espoirs reposent sur le développement de systèmes d'exploitation valorisant au mieux l'intégration agriculture-élevage. Or une intégration agriculture-élevage réussie passe par une amélioration de la conduite des animaux et une meilleure gestion des résidus de récolte au profit du troupeau et du sol. Cette étude, basée sur les pratiques des agriculteurs du Mali-Sud, s'est fixée comme objectif d'élaborer un modèle de gestion des résidus et de production de fumure organique qui tient compte des capacités d'intervention des exploitations agricoles.