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Accueil du site → Doctorat → Royaume-Uni → 1998 → Water and fertility management for crop production in semi-arid Zimbabwe

University of Nottingham (1998)

Water and fertility management for crop production in semi-arid Zimbabwe

Nyamudeza, Phibion

Titre : Water and fertility management for crop production in semi-arid Zimbabwe.

Auteur : Nyamudeza, Phibion.

Université de soutenance : University of Nottingham

Grade : Doctor of Philosophy (Ph.D.) : 1998

Water and soil fertility are major limiting factors to crop production in the semi-arid tropics. The overall objective of this study was to evaluate the effects of water conservation in conjunction with N application on the production of two crops, sorghum and maize. Analysis of soils from plots with a wide range of cultivation history, sought to evaluate the effects of period of cultivation on soil quality, and so ascertain the sustainability of the present farming system.The study was carried out in Zimbabwe (field work) and the University of Nottingham, Sutton Bonington Campus (soil analysis). In Zimbabwe field work was performed at nine sites in Natural Region 5 (typical annual rainfall of between 400 and 600 mm). The sites were in two areas which have a similar climate but different soil types. The ’core’ sites were Save Valley and Chisumbanje Experimental Stations.The field experiments compared two land topographies (LT) : tied ridges with crops in the furrows and the traditional practice of sowing on flat land, and the interaction of the two systems with N application (ranging between 0 and 160 kg ha-1). Assessment of the effects of LT and N application was mainly based on dry matter production (W) and grain yield. Other comparisons were : leaf and root development, water use and water use efficiency in terms of both rainfall received and transpired water.Maize responded more favourably to the furrow cultivation system and N application than sorghum. In Save Valley, where rainfall was more variable between sites, furrows increased W and the grain yield of maize by 1.1. to 4.1 times. There was a significant interaction between LT and N. The crop on furrows responded more to applied N than the crop on flat land and took up more N from the soil.The benefits of tied furrows were also evaluated by plotting relative W (W from flat land as a proportion of W from furrow plots) or grain yield against total rainfall and rainfall to flowering, to find the critical rainfall above which there would be no benefits of tied furrows. Based on the two seasons results, the critical rainfall to flowering was about 400 mm. Using the critical rainfall and long term rainfall data, it was found that furrows would be beneficial in most years.

Mots clés : Water conservation ; Maize ; Sorghum ; Africa Agronomy Plant diseases Horticulture Agronomy

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