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These experiments were intended as a demonstration for improved water management in irrigated areas in central Tunisia. A 36 by 36 m square, level agricultural field, sheltered with a vertical perforated plastic net 1.7 m high, was compared with an unsheltered site of the same size situated 100 m from the former. Five yield plots, each 1 by 1 m and arranged in a row across each site, were sown manually with wheat. The remaining area of the sites was broadcast sown. Irrigation was performed with sprinklers. Measurements of potential evaporation, mean wind speed, temperature, soil moisture content, and electrical conductivity were made regularly at the yield plots. The potential evaporation (evaporative demand) and the mean wind speed were, on average, smaller at the sheltered site. The mean temperature was not affected to any significant degree. The actual water use by the crop, and the grain and straw yields were larger at the sheltered site. The water use efficiency (the amount of water used to produce o...

A simple but effective evaporimeter, developed by Andersson (1969) but which has not received wide international attention, was compared with regard to evaporation with the standard methods Class A pan, Piche atmometer, and Penman calculation. The Andersson evaporimeter, made of Plexiglas, consists of a lidded cylindrical water reservoir of 0.15 L and can be placed on a pole in the terrain at chosen heights above ground level. Evaporation takes place through circular holes in the upper part of the reservoir. The reading is performed to an accuracy of 0.01 mm. Measurements were made at two meteorological stations in different climate zones: Sidi Bouzid in Tunisia in an arid climate and Kulumsa in Ethiopia in a dry sub‐humid climate. Each site covered 1 year of daily recordings. At Sidi Bouzid a 1: 1 linear relationship was found between the Andersson evaporimeter and the Class A pan, whereas at Kulumsa a 0.8: 1 relationship was obtained. Furthermore, 1: 1 relationships were found at both sites between the ...

Saturated hydraulic conductivity, Kfs,measured with the inversed auger hole method was related to root mass (living and dead roots) in the uppermost 30 cm of the soil. The studies were carried out in mountain, piedmont and plain areas. Acacia cyanophylla, Eucalyptus occidentals, Pinus halepensis, Atriplex numularia and Opuntia ficus‐indica as well as irrigated and non‐irrigated almond and olive orchards were included in the study. In older stands with well developed root systems, a significant positive linear relationship between Kfs and root mass was obtained. The regression coefficients, i.e., influence of root mass on Kfs, were generally higher in non‐aggregated than in aggregrated soil. In younger plantations (2–3 years old) the relationship was weaker and negative, probably owing to the lower proportion of dead roots and channels formed after root death. Measurements of Kfs with a double ring infiltrometer were compared to those obtained with the inversed auger hole method. Two‐to three‐fold...