Prospects of hydroponics and protected cultivation in semi-arid regions piloted in Algeria

Abstract

Algeria is used as an example for exploring and analysing the prospects of hydroponics and protected cultivation within the horticultural sector in a semi-arid climate. First step is to analyse the present horticultural situation (protected and open field cultivation, technology and knowledge level) and its local conditions such as climate (temperature, global radiation, humidity, rainfall), natural resources and market situation (segmentation and price level). According to the outcome the second step will be the improvement of the present situation with (limited) investments for growers, and a third step to suggest required changes for a higher technology and knowledge level. All need to be discussed with local parties. In Algeria the technology level is mainly low (single tunnels with soil grown crops and no climate control), while there is a wish to start with multispan greenhouses. Hydroponics was only done at a low level, but especially in multispan greenhouses there was more experience. Looking to the climate it appeared, in a model approach, that in the coastal area (Algiers) the single tunnel greenhouses are doing well, while in the desert area Biskra) the temperatures were soon too high resulting in a very short growing season/The ventilation capacity of the single tunnel is the limiting factor. At a higher technology level the multispan greenhouse with closed plastic cover is better than the open Canarian greenhouse as rainfall may be abundant in the growing season along the coast, while in the desert area without hardly any rainfall the Canarian type is a cheaper solution. Hydroponic cultivation in the coastal area can be improved by collecting rainwater in both single tunnel and multispan greenhouses. Now often poor quality groundwater is being used, while about 500 mm of rain falls in the growing season and stays unused. For the desert area hydroponics starts with desalination of the groundwater. Improvements in a higher ventilation rate in single tunnels are paid back within one year and between 3 and 4 years if additional pad and fan cooling will be used. In multispan greenhouses a high ventilation rate does not give additional investments and, consequently, no payback period, while the use of pad and fan cooling results in a payback period of 3.8 years in Algiers and 2.7 years in Biskra.