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Wageningen Universiteit (2002)

Regional analysis of maize-based land use systems for early warning applications

Rugege, D.

Titre : Regional analysis of maize-based land use systems for early warning applications

Auteur : Rugege, D.

Université de soutenance : Wageningen Universiteit

Grade : PhD thesis 2002

Résumé partiel
Conventional analytical crop growth models cannot handle actual Land Use Systems because of massive data needs, algorithm complexity and prohibitive error propagation. It is possible however to describe rigidly simplified ’Production Situations’ representing Land Use Systems with annual row crops and minimal environmental constraints. The simplest Production Situation imaginable is a Land Use System in which all constraints that can be eliminated by a farmer are indeed (assumed to be) eliminated. Crop growth and yield are then entirely conditioned by crop physiology and weather conditions, notably by the temperature and radiation during the crop cycle. The calculated production level is not the actual production but the production potential.

In many countries, water availability to the crop is the main constraint to crop production. The biophysical production potential model has therefore been extended with a water budget routine that matches actual water use with the crop’s requirement in order to calculate the "water-limited production potential". In this configuration, crop physiology, temperature, radiation and water availability condition the calculated level of crop (potential) production. This thesis discusses the use of satellite-derived rainfall data for regional analysis of water-limited yield potentials.

Monitoring and crop yield forecasting for early warning applications require insight in farmers’ reality. Often, a score of environmental and socio-economic constraints reduce on-farm production to a level that lags far behind the theoretical production potential. This thesis explores farmers’ insights, in an attempt to identify the causes and structure of the "yield gap" between potential (reference) production levels and production levels realized on-farm.

Mots clés : land use - land evaluation - regional planning - regional surveys - crop production - crop yield - remote sensing - yield forecasting - simulation models - growth analysis - growth models - losses - food production - maize - zimbabwe


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