TOTAL ELEMENT CONCENTRATION QUANTIFICATION IN SUBSTRATES

Substrates for plants may present varied composition, from a single component to a complex mixture of different materials, which may present low, adequate or high plant nutrient concentrations.
Some substrates, depending on the origin, may present high heavy metal concentrations.
The determination of total element concentrations for the chemical characterization of these materials turns an important issue not only for fertilizer recommendation but also for quality control.
The objective of this research was to evaluate the total concentrations of some elements in Brazilian commercial substrates using two heating processes, as well as to investigate the levels of heavy metals, which are related to the quality of the material.
Nine organic substrates and one inorganic, commercialized in Brazil, were used for the determination of total- P, K, Ca, Mg, S, Na, Cu, Fe, Mn, Zn, Cd, Cr, Ni and Pb concentrations, using two digestion procedures (open system acid digestion and microwave-oven digestion.
For P, K, Ca, Mg, Na, Mn, Zn and Cr the total element concentrations were very similar irrespective of the technique used, with angular coefficients close to 1.0. On the other hand, for S, Cu, Fe and Cd there was a variation above 20% in the total element concentrations.
The nitric-perchloric digestion extracted around 26% more Cu when compared with nitric- microwave method.
An opposite tendency was observed for the elements S and Fe, since the nitric-microwave procedure presented 21 to 29 % larger extraction, respectively.
Total heavy metals determination is recommended for monitoring the composition of substrates used in agriculture.

International Symposium on Soilless Culture and Hydroponics

M.F. Abreu, A.M.C. Furlani, C.A. Abreu, P.H. Santos, A. Paz-Gonzalez

heavy metals, acid digestion, microwave digestion, nitric-perchloric digestion, macronutrients, micronutrients

https://doi.org/10.17660/ActaHortic.2005.697.39