Soil isotopically exchangeable zinc: A comparison between E and L values

• Published in: Plant and soil 2004-04, Vol.261 (1-2), p.17-28
• Main Authors: Sinaj, S, Dubois, A, Frossard, E
• Format: Article
• Language: English
• Subjects: A horizons; Acid soils; Acidic soils; Agricultural land; Agricultural soils; Agrology; Agronomy. Soil science and plant productions; Alkaline soils; Biological and medical sciences; Calcium chloride; Chelating agents; Chemical extraction; Chemical properties; Chemical, physicochemical, biochemical and biological properties; Deficiencies. Phytotoxicity of elements. Salinity; diethylene triamine pentaacetic acid; dry matter accumulation; EDTA (chelating agent); Experiments; Fundamental and applied biological sciences. Psychology; Fundamental soil/plant interactions; General agronomy. Plant production; grasses; Growth chambers; heavy metals; Isotopes; isotopic exchange kinetics; Kinetics; Lolium multiflorum; Mineral components. Ionic and exchange properties; Moisture content; nutrient uptake; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant extracts; Shoots; Soil and water pollution; Soil chemistry; Soil composition; soil nutrients; Soil pollution; Soil samples; Soil science; Soil solution; soil types; Soil water; soil-plant interactions; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; topsoil; Zinc
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/B:PLSO.0000035577.64548.45

The objectives of the present paper were: (i) to determine isotopically exchangeable zinc using two isotopic exchange methods (E and L values) in a series of polluted and non-polluted Swiss agricultural soils, and (ii) to evaluate the ability of chemical extraction methods to estimate plant-available soil Zn using isotopic techniques. The surface horizon (0–20 cm) of seven polluted and non-polluted soils representing a wide range in physicochemical properties and Zn contents were sampled. An isotopic exchange kinetics (IEK) approach was used to assess, in a batch experiment, the isotopically exchangeable Zn content (E value). In order to determine the L values, a pot experiment was carried out with Lolium multiflorum (cv. Axis) in a growth chamber using a 65Zn-isotope dilution technique. Total Zn uptake and the isotopic composition (65Zn/stableZn) were determined in Lolium multiflorum for five successive cuts. The amounts of zinc extracted by different chemicals were compared with L values and regression parameters were estimated. The isotopic composition in soil extracted by DTPA and EDTAAc at the end of the pot experiment was also determined. Results showed that the equation describing the increase of isotopically exchangeable Zn with time could be extrapolated to three months for polluted and non-polluted neutral and acidic soils, and that the results were not different from the amount of isotopically exchangeable Zn experimentally determined with Lolium multiflorum (L value). In alkaline soils however, results suggest that either 65Zn sorption occurred in the batch experiment or that the concentration of Zn in the soil solution had been overestimated, leading to an overestimation of the E value compared to the L values. Furthermore, the specific activities measured in DTPA and EDTA extractions at the end of the pot experiment were significantly different compared to the specific activity of the plant, showing that both these chelating agents extract neither all the available soil Zn nor only the available soil Zn for plants.