Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Pays-Bas → 2003 → Soil quality and rice productivity problems in Sahelian irrigation schemes

Wageningen Universiteit (2003)

Soil quality and rice productivity problems in Sahelian irrigation schemes

Asten, P.J.A. van

Titre : Soil quality and rice productivity problems in Sahelian irrigation schemes

Auteur : Asten, P.J.A. van

Université de soutenance : Wageningen Universiteit

Grade  : Doctor Thesis 2003

Présentation
In irrigation schemes in the Sahel, rice yields and cropping intensity are still far from their potential and some of the 10-20 year old irrigation schemes experience declining yields. The large investments in irrigation infrastructure, made to improve food security, to generate income, and to reduce rice imports, are currently at stake. Many farmers and researchers suggested that the rice productivity problems might (partly) be due to salt-related soil degradation. Sahelian irrigation waters contain little salt, but are relatively rich in carbonates (RA calcite > 0). In the hot and dry Sahelian climate, irrigation with such waters could lead to the formation of an alkaline (high pH) and sodic (high sodium content) soil, which has a low productivity. We investigated the causes of declining rice productivity in the irrigation schemes of Foum Gleita (Mauritania) and the Sourou Valley(Burkina Faso). We found that rice productivity problems in Foum Gleita were primarily caused by N and P deficiency, while Zn deficiency prevailed in the Sourou Valley. These nutrient deficiencies were caused by no or insufficient application of N, P and Zn fertilizers, in combination with low plant available N, P and Zn in the soil. The alkaline-calcareous nature of the studied soils likely contributed to the low availability of N through volatilization, and low availability of P and Zn through precipitation of or adsorption onto carbonate minerals. Application of ample N, P and Zn fertilizer increased yields at the study sites from 3-4 t ha -1 to 5-6.5 t ha -1 . However, the required chemical fertilizers are often expensive or not available on the local markets, which hampers adoption of improved fertilizer recommendations by the resource-poor Sahelian rice farmers. Application of organic amendments (a.o. rice straw) at a rate of 5 t ha -1 often improved yields at the study sites by 1-2 t ha -1 . In Foum Gleita, the yield increasing effect was attributed to improved N availability, while in the Sourou Valley, organic matter amendments improved Zn uptake.

Mots clés : ORYZA SATIVA / RICE / CROP PRODUCTION / FERTILIZERS / ALKALINIZATION / NUTRIENT DEFICIENCIES / CROP YIELD / IRRIGATION SCHEDULING / SAHEL / MAURITANIA / BURKINA FASO / MALI / SOIL QUALITY

Résumé de la thèse

Version intégrale

Page publiée le 17 mars 2006, mise à jour le 3 juin 2022