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ENVIRONMENT and DEVELOPMENT
Issue 7, Volume 3, July 2007
Title of the Paper: Environmentally Useful Technique - Portulaca Oleracea
Golden Purslane as a Salt Removal Species
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Authors: A. Hamidov, J. Beltrao, C. Costa, V. Khaydarova, S. Sharipova
Abstract: The application of large volumes of freshwater and the heavy use of chemical substances (fertilizers and pesticides) are methods which have been used to mitigate salinity and increase the salt tolerance of agricultural crops in salt-affected soils. However, the intense use of these conventional techniques has attracted public attention due to the environmental pollution and to the contamination of groundwater resources. In recent years, a new environmentally safe and clean technique of planting salt (ion)-removing species in the salt-affected soils has been introduced to mitigate the salinity problems. The salt removal potential of Portulaca oleracea golden purslane has been assessed under field experiments conducted in the Khorezm Region, northwest of Uzbekistan. Portulaca oleracea was planted during the summer in two different salt-affected soils, with and without irrigation. The results have revealed that, when a slightly saline groundwater table remained at a depth under surface near 1.1 m., no irrigation was required as capillary rise from the groundwater played a significant role in meeting the demand of plants for water and increasing transpiration. A high ion accumulation was observed (497 kg ha-1), which corresponds to 16.8% of the total amount of soil salts in the 0-10 cm topsoil layers. Furthermore, the highest dry biomass production was 3948 kg ha-1, without any irrigation practices (in comparison to 489 kg ha-1 with irrigation practices). Results of this study clearly indicate that Portulaca oleracea golden purslane could be used to combat salinity and rehabilitate saline soils in the northern part of Uzbekistan.
Keywords: soil salinity, conventional techniques, phytoremediation, salt removing species, salt extraction, Portulaca oleracea golden purslane.
Title of the Paper: Apocynum Lancifolium and Chenopodium Album - Potential
Species to Remediate Saline Soils
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Authors: A. Hamidov, J. Beltrao, A. Neves, V. Khaydarova, M. Khamidov
Abstract: In semi-arid areas of Uzbekistan, rainfall is so scarce that irrigated agriculture is carried out by diverting Amudarya and Syrdarya rivers to farming areas. However, mismanagement of these water resources over the past forty years has threatened agricultural productivity. An elevated groundwater table associated with long-term irrigation and inappropriate drainage infrastructures have resulted in secondary soil salinization and major waterlogging problems. Rehabilitation of these salinized lands by means of installation of appropriate drainage infrastructures requires major financial investments. The potential capacity of Chenopodium album and Apocynum lancifolium, native naturally grown wild species, have been evaluated to its removal of ions from the salt-affected soils of Khorezm Region, northwest of Uzbekistan. Soil agro-physical and agro-chemical properties were determined to characterize the soil profile in the study area. Salt removal capacity and plant yield were determined. The results of investigation have clearly indicated that Chenopodium album produced the highest dry biomass 3.25 tons ha-1 and accumulated highest 569.6 kg ha-1 of salt. Hence, it can be used to rehabilitate salt-affected soils since this technique is low cost and could be used by farmers. Although, Apocynum lancifolium was developed in high saline soils, but had removed very low amount of salts and thus, can be considered as a salt-tolerant but not a salt-removing species.
Keywords: Soil salinity, salt extraction, halophytic wild plants, phytoremediation, environmental pollution, crop yield