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

Mircea Mihalache,Catalina Calin,Gina Vasile Scaeteanu,Leonard Ilie,Roxana Maria Madjar

doi:10.37358/rc.20.5.8146

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.

Highlights

Sewage sludge is a semisolid material resulted from sedimentation of the suspended solid during processes which occur at wastewater treatment plants
The factors taken into consideration, parts of experimental model, were: A factor - sewage sludge fertilization with seven degrees representing equivalent doses varying between 0-600 kg N/ha (a1 unfertilized with sewage sludge; a2 - fertilization with sewage sludge corresponding to 100 kg N/ha; a3 - fertilization with sewage sludge corresponding to 200 kg N/ha; a4 - fertilization with sewage sludge corresponding to 300 kg N/ha; a5 - fertilization with sewage sludge corresponding to 400 kg N/ha; a6 fertilization with sewage sludge corresponding to 500 kg N/ha; a7 - fertilization with sewage sludge corresponding to 600 kg N/ha) and B factor - mineral fertilization (NPK) with two degrees: b1 N0P0K0 and b2 - N100P100K100
Influence of sewage sludge application on Cu, Mn, Zn contents in oat grains The results evidenced that copper levels increased significant with sewage sludge fertilization starting with a dose equivalent with 200 kg N/ha (Table 2)

Summary

Introduction

Sewage sludge is a semisolid material resulted from sedimentation of the suspended solid during processes which occur at wastewater treatment plants. Tsadilas et al [4] found that after sewage sludge treatments, the nitrogen content in the dry matter of wheat increased. Morera et al [5] reported that sludge doses of 80, 130 and 160 t/ha increased the average dry weight of sunflower plants (Helianthus annuus L.) in comparison with control variant. Fertilization with sewage sludge produced for sunflower plants significant increases of stem, leaves and calatidium mass [6]. Yield of rice increased by 60%, 111%, 125%, 134% and 137% at 30, 45, 60, 90 and 120 t/ha sewage sludge rates, respectively in comparison with those grown in unamended soil [7]

Objectives

Methods

Results