干旱区生态环境知识资源中心

The increasingly water demand and the lack of natural resources in arid and semi-arid areas justify the present interest in the re-use of wastewater. Since 1995 purified and ozone-treated wastewater from Almeria (Spain) has been used to irrigate greenhouse crops. The higher nutrient content levels of this effluent requires special management strategies. Melon 'Galia' in a spring cycle (124 days) and tomato 'Daniela' in an autumn-winter cycle (185 days) were grown under greenhouse conditions. The crops were irrigated with groundwater or with purified wastewater. Purified wastewater was obtained from the Almeria Purifying Plant after an ozone tertiary treatment, ground water was obtained by desalinizing underground water. To prepare the nutrient solution the chemical composition of each type of water was determined and N and K were added accordingly to obtain similar nutrient solutions. Effluents provided significant amount of N, P and K; this had positive effects on the addition of fertilizer salts since the input of nutrients was reduced. As no significant differences were found among treatments on the tested production parameters in both crops, the nutrient use efficiency was higher in the wastewater treatment. Foliar concentrations of N, P and K were similar in both treatments and crops.