Impacts of Using Mineral Fertilization Combined with Sewage Sludge in the Amendment of Luvisol on Oat Crop. II. Influence on Metal Accumulation

Abstract

The objective of the present paper was to investigate the effects of sewage sludge application on metals (Cu, Mn, Zn, Cd, Co, Pb) accumulation in oat (Avena sativa L.) grains, Somesan variety. It were used various doses of sewage sludge corresponding to equivalent doses of 0-600 kg N/ha associated or not with NPK mineral fertilization. The results evidenced that copper and zinc levels in oat grains increased significant with sewage sludge fertilization starting with a dose equivalent with 200 kg N/ha. Mineral fertilization led to significant decrease of copper content in comparison with sewage sludge treatments only. For manganese, fertilization with sewage sludge has produced a significant decrease, this trend being accentuated up to the equivalent dose of 300 kg N/ha. For cadmium, application of sewage sludge in an equivalent dose of 200 kg N/ha led to concentrations in oat grains higher than 1 mg Cd/kg (imposed limit for grains used for animal feed). This behavior is a consequence of high cadmium content of sewage sludge (of 7.2 times over maximum admitted limit). Cobalt contents of oat grains increased with sewage sludge doses, but the levels are between normal values and concordant with literature data. Application of sewage sludge in an equivalent doses of 500 and 600 kg N/ha generated a significant increase of lead content in oat grains, average values being 1.87 and 2.17 mg Pb/kg, respectively.

Research on the Management of the Main Chemical Properties of Chromic Luvisols From Farms/Households Agritouristic in Dolj, in the Period 1995-2021

“…Furthermore, it has been observed that on andosols, heavy metals are exclusively of paedogenetic origin (derived from the parent material in the pedogenesis processes), and their natural geochemical associations are undisturbed. On anthroposols, heavy metals are mostly of anthropogenic origin, and the degree of stabilization of geochemical associations is relatively low, being determined by the form of entry of heavy metals into the soil and their residence time (Mihalache et al, 2014;Huang et al, 2019). The analysis of the data presented in Table 2 shows that the average values of the heavy metal content increased by several units compared to other chromic soils studied by us and previously published in other journals.…”

“…The parent material on which it was formed is generally composed less often of loess deposits, with the predominance of marly deposits and marly clays which hinder the internal drainage capabilities of the soil. The puddle phenomenon is also manifested due to the compaction of the land, under the continuous action of the equipment and machines used for agriculture (Mihalache et al, 2014).…”

“…Some of them have a beneficial role, physiological speaking, but with increasing concentration above the tolerance limit they become toxic, both for plants and for animals and humans (Beek et al, 1991), Most heavy metals detected in the soil have different origins: of lithogenic origin -they come directly from the lithosphere (parent material) or are of anthropogenic origin -originating directly or indirectly the result of human activities. The mere presence of the metal in the soil is not enough for it to become harmful to living organisms, but its bioactive chemical form (s.s. toxic) (Bervoets & Blust, 2003), Once in the soil, heavy metals interact with clay minerals, humic substances, extracellular enzymes, microorganisms, organic and inorganic ligands, or associate with mobile organic or inorganic colloidal particles (Lăcătuşu & Lăcătuşu, 2008;Mihalache et al, 2014). Furthermore, it has been observed that on andosols, heavy metals are exclusively of paedogenetic origin (derived from the parent material in the pedogenesis processes), and their natural geochemical associations are undisturbed.…”