Do New-Generation Recycled Phosphorus Fertilizers Increase the Content of Potentially Toxic Elements in Soil and Plants?

Agnieszka Saeid,Magdalena Jastrzębska,Marta K Kostrzewska,Wiesław P Jastrzębski

doi:10.3390/min11090999

Abstract

Phosphorus (P)-rich secondary raw materials can provide a valuable base for modern mineral fertilizers, provided that the new formulations do not load the soil–plant system with potentially toxic elements. Fertilizers from sewage sludge ash (SSA) and/or animal bones, activated by phosphorus-solubilizing bacteria (Bacillus megaterium or Acidithiobacillus ferrooxidans), were tested in field experiments in north-eastern Poland. The reference provided treatments with superphosphate and treatment without phosphorus fertilization. In one experiment, all P-fertilizers were applied at a P dose of 21 kg·ha−1, and in the other three experiments, three P doses were adopted: 17.6, 26.4, and 35.2 kg·ha−1. The effect of recycled fertilizers on the content of arsenic (As), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn) in the soil, in wheat grain and straw (test plant), weeds, and post-harvest residues was investigated. The application of recycled fertilizers in P amounts up to 35.2 kg·ha−1 did not change the As, Cr, Ni, Cu, or Zn contents in the soil and plant biomass. The contents of these elements in soil were below the permissible levels for arable land in Poland. Their concentrations in wheat grain and straw did not exceed the permissible or suggested limits for plant material to be used for food and feed, while in the weed and post-harvest residue biomass, they usually fell within the biological plant variability ranges.

Highlights

Agriculture is the major food supplier for the growing world population, it is one of the economic sectors with the largest environmental impact [1]
This paper focuses on the effect of fertilizers from sewage sludge ash (SSA) and/or animal bones, activated by phosphorus-solubilizing microbes (PSM) (Bacillus megaterium or Acidithiobacillus ferrooxidans) on the content of As, Cr, Ni, Cu, and Zn in the soil, in wheat grain and straw, wheat associated weeds, and post-harvest residues
The Potentially toxic elements (PTE) presence in the tested P-fertilizers (Table 1) suggests the possibility of their accumulation in soil due to fertilizer application, which should potentially become apparent in comparison to no P treatments

Summary

Introduction

Agriculture is the major food supplier for the growing world population, it is one of the economic sectors with the largest environmental impact [1]. Certain PTE, such as Cu, Fe, Ni, Zn, and even Cr(III), are essential elements to organisms [6]; they cause toxic effects when present in excessive quantities [7]. Their functions and potential toxicity have been comprehensively discussed in the literature [8,9,10]. Several PTE, e.g., As, Pb, Cd, and Hg, are non-essential to metabolic and other biological functions [11,12] These are hazardous to organisms even at low levels [7] and harmful in various respects [13]. Persistent toxicity and bioaccumulation in food chains make PTE one of the most problematic types of pollutants [14]

Methods

Results

Conclusion