Radiological impact of phosphogypsum surface application in a no-till system in Southern Brazil

Nivea Maria Piccolomini Dias,Luiz Fernando Pires,Márcio Arruda Bacchi,Elisabete Aparecida De Nadai Fernandes,Eduardo Fávero Caires

doi:10.1590/s0100-204x2010001200017

Nivea Maria Piccolomini Dias, Luiz Fernando Pires + Show 3 more

Open Access

https://doi.org/10.1590/s0100-204x2010001200017

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Abstract

The objective of this work was to determine the impact of phosphogypsum application on 226Ra and 228Ra activities in the soil and on their accumulation in soybean grains. A field experiment was carried out in Paraná state, Brazil, on a loamy Typic Hapludox, under no-till system, with increasing phosphogypsum rates: 4, 8, and 12 Mg ha-1. GammA ray spectrometry was carried out using HPGe detectors with 45 and 10% relative efficiencies, for soybean grains and soil, respectively. No increment of 226Ra and 228Ra activities was observed due to the increase in phosphogypsum rates in the soil, and a small reduction was noticed in the grains. Average values found for 226Ra and 228Ra activities were 37 and 57 Bq kg-1 in the soil and 1.44 and 3.19 Bq kg-1 in soybean grains. The application of phosphogypsum for no-till soybean production is a safe practice regarding the risks of radiation damage to human health

Highlights

Phosphogypsum (PG) is a by‐product of the phosphate fertilizer industry that contains mainly calcium sulfate (CaSO4.2H2O) and small concentrations of phosphorous and fluorine
The objective of this work was to determine the impact of phosphogypsum (PG) application on 226Ra and 228Ra activities in the soil and on their accumulation in soybean grains
It should be noticed that 228Ra concentrations found in the soil were almost twice as much as 226Ra concentrations, which might be due to the soil parent material and to the use of fertilizers or other agricultural inputs

Summary

Introduction

Phosphogypsum (PG) is a by‐product of the phosphate fertilizer industry that contains mainly calcium sulfate (CaSO4.2H2O) and small concentrations of phosphorous and fluorine. The huge demand for phosphate fertilizer with high P content in agriculture has led to a global production of about 170 million megagrams of PG per year (Abril et al, 2008). Surface‐applied PG followed by its leaching to acidic subsoils results in improvement of root growth and higher absorption of water and nutrients by plant roots as a result of the increase in calcium content, the formation of less toxic aluminum species (AlSO4+) and precipitation of Al3+ (Shainberg et al, 1989; Carvalho & Raij, 1997; Caires et al, 2003). No‐till systems with diversified crop rotations have stood out as one of the most effective strategies to improve the sustainability of farming in tropical and subtropical regions, contributing to minimize soil and nutrient losses by erosion. To control soil acidity in established no‐till systems, lime is spread on the surface without incorporation.

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