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Fernandez J.E.,Institute Recursos Naturales y | Ferreira M.I.,University of Lisbon
Acta Horticulturae | Year: 2011

The increasing demand of fresh water from different sectors puts pressure in scientists and engineers to develop more effective ways of using the available water resources. In Spain and Portugal, countries of Mediterranean climate with hot and dry summers, the allocation of water resources is especially controversial. This emphasises the need for a rational use of water. We present features and recent developments of Spanish and Portuguese water policies and some consequences on the use of land and water. We consider how social, economic and environmental problems might evolve in the expected scenarios of population growth and climatic change, and analyse the response from the scientific community to the new challenges. Finally, we pointed out that the combined efforts of professionals and users provide useful tools for satisfying the consumers demand at the same time that the environmental footprint is minimized. © ISHS.

Gamiz B.,Institute Recursos Naturales y | Celis R.,Institute Recursos Naturales y | Hermosin M.C.,Institute Recursos Naturales y | Cornejo J.,Institute Recursos Naturales y
Soil Science Society of America Journal | Year: 2012

Research on organoclays as sorbents of pesticides has shown the usefulness of these materials both as soil amendments and as pesticide supports, to prolong the effi cacy and reduce the environmental impact of soil-applied pesticides. Organoclays can also be formed in situ by direct modifi cation of smectiterich soil clays through treatment with appropriate organic cations. In this work, laboratory experiments were conducted to investigate the effect of the addition to soil of a natural organic cation, spermine, on sorption (batch equilibration procedure), persistence (incubation experiments), and leaching (column experiments) of the herbicide fl uometuron. Four soils differing in their clay contents and mineralogy were used. A sevenfold increase in the fl uometuron sorption distribution coeffi cient, K d, by the presence of spermine was observed for a clay soil rich in smectites (Soil 1), whereas the effect on fl uometuron sorption was negligible for a soil with similar clay texture but lacking smectites (Soil 4) and for a loamy sand soil with very low content in smectites (Soil 3). A sandy loam soil (Soil 2) with moderate smectite content had an intermediate behavior. The increase in fl uometuron sorption was thus related to the smectite content of the soils, strongly indicating that reaction of spermine with soil smectites formed in situ an organoclay complex with high affi nity for fl uometuron. The simultaneous application of fl uometuron and spermine to the smectite-rich soil retarded the leaching of the herbicide but, at the same time, increased the total amount of fl uometuron leached from 25 to 52%. This was attributed to the fact that spermine, apart from increasing sorption, also prolonged the persistence of fl uometuron in the smectite-rich soil. In contrast, the presence of spermine had no effect on the leaching pattern of fl uometuron in the clay soil lacking smectites. The results indicated that the application of suitable organic cations to smectitic soils can be a useful strategy to control pesticide retention and persistence in the soil environment. © Soil Science Society of America.

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