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Accueil du site → Doctorat → Canada → The effect of mulches on hydrologic and erosional processes, soil moisture and crop yield, in highly crusting tropica semi-arid soils, Baringo, Kenya

University of Toronto (1992)

The effect of mulches on hydrologic and erosional processes, soil moisture and crop yield, in highly crusting tropica semi-arid soils, Baringo, Kenya

Kamar, Margaret Jepkoech

Titre : The effect of mulches on hydrologic and erosional processes, soil moisture and crop yield, in highly crusting tropica semi-arid soils, Baringo, Kenya

Auteur : Kamar, Margaret Jepkoech,

Université de soutenance : University of Toronto

Grade : Doctor of Philosophy (PhD) 1992

Résumé
Moisture is a limiting factor for plant production in semi-arid lands. The effects of two types of mulches, an inorganic (stone) and an organic (Euphorbia tirucalii) on hydrologic and erosional processes, moisture conservation and crop yield, were studied on a highly crusting soil, in a tropical semi-arid region. The mulches were applied on the soil surface at six different percentage covers, 100, 75, 50, 25, 15 and 10%, and the control was 0%. Data was collected under four different field experimental conditions : natural rainstorm, partial irrigation, simulated rainfall and a pot, lysimeter type, experiment for evaporation losses. Mulches generally increased infiltration and decreased runoff compared to bare surfaces. Infiltration was closely related to surface porosity and permeability. Stones maintained better permeability and hence deeper infiltration than Euphorbia. Runoff response was related to rockflow and the easily crusted inter-stone areas under stone mulching, while more related to surface storage and mulch absorption under Euphorbia. This resulted in higher runoff under stone than Euphorbia. The bare surface crusted rapidly, decreasing infiltration and increasing runoff. Sediment losses were highest under Euphorbia due to the inefficient protection of the incompletely sealed soil surface, but lowest under stone mulch due to the efficient protection of the mulched surfaces and rapid crusting of inter-stone areas. The bare surfaces crusted and resisted slash detachment. The implications are discussed. Moisture storage increased under both mulches compared to the bare control, increasing positively with mulch application rate. Daily cumulative evaporation losses decreased with increase in cover. Stone mulches showed greater suppression of evaporation as well as higher soil moisture storage than Euphorbia. This is attributed to the greater efficiency of stones to prevent evaporation while Euphorbia, as an organic permeable material, acted as a conduit for water evaporation from the soil surface. Mulching increased crop yields significantly. Yield was closely related to moisture storage and thus stone mulching gave better yields. Generally, the effect of mulches on moisture storage through suppressed evaporation was more important than through reduced runoff.

Présentation (Amicus)

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