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In the Mediterranean region, difficult climate conditions and inadequate land management have led to a reduction of the organic matter content of soils. As a solution, municipal solid waste (MSW) compost and sewage (S) sludge were investigated for their effectiveness in maintaining soil fertility. Clayey-loamy soil was amended with 0, 40, and 80 t ha−1of MSW compost or S sludge and cultivated with Triticum durum. Soil was sampled 15 and 70 days after sowing, and the activities of arylsulphatase, phosphatase, dehydrogenase (DH), -glucosidase (-GLU), urease, and catalase (CAT) were assayed. The wheat was harvested after 68 days, then soil properties as well as plant growth and K+and Na+contents were determined.

AbstractThe changes in biomass production, root length, mineral nutrition, potassium absorption efficiency (KAE), and potassium use efficiency (KUE) of the halophytesCatapodium rigidumandHordeum maritimumin response to potassium availability were assessed under natural conditions. Plants were cultivated in the greenhouse of the experimental station of the Biotechnology Centre of Borj Cédria (a Mediterranean coastal area) 30 km south-east of Tunis for four months from the autumn to winter of 2007–2008.H. maritimumbiomass production was not significantly affected by the K+concentration, butC. rigidumgrowth was increased significantly with increasing K+concentration in the medium. Root/shoot dry weight ratio remained constant inC. rigidum, but decreased significantly at 1000 and 3000µM K+inH. maritimum.KAE increased but KUE decreased significantly with increasing K+concentration in the medium in both species. However, KAE was higher inH. maritimumthan inC. rigidumshowing a contrasting response to K+concentration between the two species. Overall, the maintenance of a cationic balance may be explained by cation antagonism. The lower K+requirement ofH. maritimumto express its optimal growth can be attributed to its higher efficiency to acquire and transfer K+to shoots.