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This paper presents analysis and results of a joint research project between the Technical and Scientific Research Center on Arid Regions (CRSTRA) in Biskra (Algeria) and the Department for Agricultural Engineering of the Kassel University (Germany). An auto-regulative permeable pipe buried beneath the soil surface was tested in greenhouse trials at the experimental station El Outaya near Biskra (Algeria) under semiarid to arid conditions. The new irrigation system works at low pressure to allow an auto-regulative functioning of the pipe, based on porous irrigation pipes as an upgrade of both subsurface and traditional pot irrigation. In clay pot (pitcher) irrigation unglazed porous clay pots are embedded in the ground and filled with water, which eventually drains through the porous pot wall. Savings of up to 70 % compared with conventional irrigation methods were observed, as well as a significant reduction of fertilizer requirements.
To sustain a constant low system head a mechanical float valve is upstream of the irrigation pipes ensuring a continuous water filling of the pipe. The irrigation method works automatically and independent of energy supply.
To compare the new irrigation system with the drip irrigation technique two greenhouses were equipped with drip irrigation and the permeable pipes respectively. The greenhouses were divided into different plots and planted with tomatoes. Two types of irrigation water were tested; surface water from a local dam and groundwater with a higher salinity. Results show 60 % higher yield for the permeable pipe irrigation with 48 % less water consumed compared to drip irrigation when using poor quality / salty irrigation water. The water had no measurable impact on the soil structure, and the tomato plants showed better health and performance (plant height, fruit diameter and weight) compared to the drip plots.
