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Accueil du site → Doctorat → États-Unis → 1990 → Thatched mat windbreaks influences on the Harmattan : Wind and millet production in the Sahel

University of Wisconsin - Madison (1990)

Thatched mat windbreaks influences on the Harmattan : Wind and millet production in the Sahel

Bashir, Dogara

Titre : Thatched mat windbreaks influences on the Harmattan : Wind and millet production in the Sahel

Auteur : Bashir, Dogara

Université de soutenance : University of Wisconsin - Madison

Grade : Doctor of Philosophy (PhD) 1990

Résumé
Thatched mat fences were tested as windbreaks to protect millet (Pennisetum thyphoides, Burm) crop in the arid region of Sokoto State, Nigeria. The effects of the fence windbreaks, set up in three porosities (0%, 30%, and 50%), on millet growth, water use and yield were investigated and compared to the effects of a twenty year old shelterbelt. The 30% and 50% fence windbreaks were comparable to the shelterbelt in improving growth rate and yield of millet. Compared to the open, yield was increased by 16%, 19%, and 18% behind the shelterbelt and the 30% and 50% fence windbreaks respectively. Yield increase behind the 0% fence windbreak was only 2%. Crops in the proximity of the shelterbelt had the lowest yield due to shading, less moisture availability and possibly allelopathy. The shelterbelt and the 30% and 50% fence windbreaks enhanced the water use efficiency of millet crop by 21%, 26%, and 26% respectively ; while the 0% fence increased the efficiency by only 5%. Water use in the vicinity of the shelterbelt was predictably higher than the rest of the field. The fence windbreaks were found to be effective for only one growing season. Rate of deterioration was found to be inversely proportional to the original porosity of the windbreak. The medium dense windbreaks (30% and 50% fence windbreaks, and the shelterbelt) had larger range of influence on wind speed, mostly on the leeward side. The 0% fence windbreak was the most effective on the windward side and close to the barrier on the leeward side. Drag coefficients of the fence windbreaks, estimated using the momentum transfer method, were very similar to values reported from wind tunnel studies and values obtained from slat fence windbreaks.

Mots clés : Agronomy, Nigeria, Applied sciences, Biological sciences, Agricultural engineering

Présentation

Page publiée le 20 février 2015, mise à jour le 3 février 2019