Agricultural use of sediments from the Albufera Lake (eastern Spain)

Dredging of the Albufera Lake, a very important natural area of eastern Spain, has been proposed to remediate the silting process, but a very large amount of sediments would be generated. To assess the feasibility of applying these to the sandy agricultural soils surrounding the lake, three rates (180, 360 and 720 t/ha) of four different sediments, corresponding to different degrees and sources of contamination, were tested by mixing with a soil obtained from the area of potential application. The effects on the soil properties and yield and nutrient contents of lettuce (Lactuca sativa L.) and tomato (Lycopersicon esculentum Mill.) were studied. As the most relevant changes, sediments improved the soil water-retention and cation exchange capacity of the mixture, but increased its salinity and heavy metal contents. Yield of lettuce increased with parallel to the sediment applications whereas tomato growth and yield remained unaffected. Significant effects were also found on the nutrient contents of the plant tissues, depending on the sediment and application rate used, but no heavy metal accumulation in plants could be detected. According to the results, the application of appropriate rates of sediments to the agricultural soils surrounding the lake seems to be a sound practice to avoid problems arising from the disposal of large amounts of dredged material, and to improve the properties of the sandy soils of the area.