RESUMEN
A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al-F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF2(1+) and AlF(2+) complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future.
Asunto(s)
Aluminio/análisis , Fertilizantes/toxicidad , Fluoruros/farmacología , Hordeum/crecimiento & desarrollo , Contaminantes del Suelo/farmacología , Aluminio/toxicidad , Compuestos de Aluminio/análisis , Calcio/deficiencia , Fluoruros/análisis , Fluoruros/toxicidad , Hordeum/efectos de los fármacos , Concentración de Iones de Hidrógeno , Fósforo/toxicidad , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Suelo/análisis , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidadRESUMEN
Ingestion of soils with high fluoride (F) concentration may cause chronic fluorosis in grazing animals. Analysis of New Zealand pasture soils with long-term phosphorus (P) fertilisation histories showed that total surface soil (0-75 mm depth) F concentration increased up to 217-454 mg kg-1 with P fertiliser application. One-third to two-thirds of F applied in fertilisers resides in the top 75 mm soil depth. Pasture forage accumulation of F was low, and therefore, F intake by grazing animals through pasture consumption is expected to be much lower than F intake by soil ingestion. Ten annual applications of single superphosphate (30 and 60 kg P ha-1 year-1) to a Pallic Soil (Aeric Fragiaqualf) significantly increased total F and labile F (0.01 M CaCl2 extract) concentrations to 200 and 120 mm depths, respectively, of the 300 mm depth investigated. The mobility of F in the soil profile was similar to two other elements, P and cadmium derived from the fertiliser.