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A short-term pot experiment was made to evaluate the effectiveness of municipal solid waste compost amendment on salt-affected soil. Hordeum maritimum plants were cultivated in pots filled with a clay-loam soil containing 0 or 40 t ha-1 of compost and irrigated with tap water at 0 or 4 g l-1 NaCl. Soil properties and heavy metal (Zn2 +, Pb2 +, Cd2 +) accumulation were investigated. Municipal solid waste compost application significantly increased the soil contents of carbon, nitrogen and potassium under both non-saline and saline conditions. Soil heavy metal concentrations increased substantially too, but the recorded values were below the toxicity limits. Interestingly, plants subjected to the salt-compost interaction were more vigorous, compared with those grown on non-amended soil. Altogether, our data indicate that short-term utilization of municipal solid waste compost at 40 t ha-1 may be of potential interest in the perspective of the rehabilitation of salt-affected soils. Yet, it must be stressed that the present findings are preliminary and need to be further evaluated under field conditions before practical recommendations can be inferred. [ABSTRACT FROM AUTHOR]

Abstract: A field plots experiment was carried out to assess the effects of repeated application of municipal solid waste compost in comparison to farmyard manure on the accumulation and distribution of trace metals, as well as organic carbon and nitrogen in Tunisian calcareous soil. Compared with untreated soil, the application of the two organic amendments significantly increased the organic carbon and nitrogen contents of the soil. Particle-size fractionations showed that carbon and nitrogen were mainly found to occur in the macro-organic matter fraction (80%). The two organic amendments significantly increased organic carbon in the macro-organic and mineral >150μm fraction and the 150–50μm fraction, as well as the organic nitrogen in 150–50μm and macro-organic fraction. Compared with farmyard manure, municipal solid waste compost significantly increased total Cd, Cu, Pb and Zn contents in the topsoil. These trace metals were mainly present in the macro-organic matter fraction. Significant increases of Cu, Zn and Pb were detected in the 150–50μm, <50μm and macro-organic fractions after application of municipal solid waste compost. A significant increase of Cd content was only observed in the 150–50μm fraction. The trace metals also showed different fractionation patterns when the BCR sequential extraction scheme was applied on untreated and compost-treated soil. The residual fraction was found to be the major fraction, especially for Cu, Cr, Ni and Zn. In contrast, Cd was mainly present in the acid-extractable and reducible fraction, whereas Pb was mainly associated with the reducible fraction. [Copyright &y& Elsevier]

The efficiency of composted municipal solid wastes (MSW) to reduce the adverse effects of salinity was investigated in Hordeum maritimum under greenhouse conditions. Plants were cultivated in pots filled with soil added with 0 and 40tha−1 of MSW compost, and irrigated twice a week with tap water at two salinities (0 and 4gl−1 NaCl). Harvests were achieved at 70 (shoots) and 130 (shoots and roots) days after sowing. At each cutting, dry weight (DW), NPK nutrition, chlorophyll, leaf protein content, Rubisco (ribulose-bisphosphate carboxylase/oxygenase) capacity, and contents of potential toxic elements were determined. Results showed that compost supply increased significantly the biomass production of non salt-treated plants (+80%). This was associated with higher N and P uptake in both shoots (+61% and +80%, respectively) and roots (+48% and +25%, respectively), while lesser impact was observed for K+. In addition, chlorophyll and protein contents as well as Rubisco capacity were significantly improved by the organic amendment. MSW compost mitigated the deleterious effect of salt stress on the plant growth, partly due to improved chlorophyll and protein contents and Rubisco capacity (−15%, −27% and −14%, respectively, in combined treatment, against −45%, −84% and −25%, respectively, in salt-stressed plants without compost addition), which presumably favoured photosynthesis and alleviated salt affect on biomass production by 21%. In addition, plants grown on amended soil showed a general improvement in their heavy metals contents Cu2+, Pb2+, Cd2+, and Zn2+ (in combined treatment: 190%, 53%, 168% and 174% in shoots and 183%, 42%, 42% and 114% in roots, respectively) but remained lower than phytotoxic values. Taken together, these findings suggest that municipal waste compost may be safely applied to salt-affected soils without adverse effects on plant physiology. [Copyright &y& Elsevier]

It is obvious that the application of solid waste compost improves the soil fertility. These wastes, however, may also have some negative effects on the agricultural environment due to their metal content. This research aimed at evaluating the influence of Tunisian municipal solid waste compost and farmyard manure on some chemical properties and the distribution of heavy metals in a calcareous Tunisian soil (clayey–loamy soil). A field plot experiment, without vegetation, was installed since 1999 at the experimental farm of the Agronomic National Institute of Tunis (INAT) in the region of Mornag (20km south of Tunis, Tunisia). During 5 years, the field received yearly the following treatments: 0, 40, 80 and 120t/ha of municipal solid waste compost and 0, 40 and 120t/ha of manure. The fractionation of heavy metals in the soil was evaluated after 5 years using a sequential extraction procedure. The application of the two amendments was found to increase the content of organic matter, the total nitrogen content and the electrical conductivity, whereas it slightly decreased the soil pH. The addition of manure did not have a significant effect on the accumulation of heavy metals in the soil, whereas compost application increased the total concentration of heavy metals in the soil. The distribution of heavy metals between the different fractions in untreated and treated soils showed the residual fraction to be dominant, followed by the fraction bound to Fe and Mn oxides. The amount of Cu bound to the organic fraction increased with the application rate, which is probably caused by the formation of organic complexes. For the other metals, the increase of the association with organic matter is very limited. The application of compost moreover increases the amount of Zn associated with Fe and Mn oxides. The “Mobility Factor (MF)” was quite low and did not change after the 5-year application of the two organic amendments. It always remained lower than... [Copyright &y& Elsevier]