Application of Phosphogypsum and Organic Amendment for Bioremediation of Degraded Soil in Tunisia Oasis: Targeting Circular Economy

Abstract

This study was conducted at the Institute of Arid Regions of Gabes in Tunisia. Three plots were left as controls and received no input, three plots were amended with cattle manure with a dose equivalent to 37.5 t/ha, and nine plots were amended with phosphogypsum in three doses (12.5 t/ha, 25 t/ha, and 50 t/ha), with three repetitions for each dose. A pot test to determine the germination index and radioactivity analysis was carried out in the laboratory. The results showed that organic manure amendments and phosphogypsum improved the germination rate of the different crops (jute mallow, turnip, and oat) compared with the control. At the same time, the 50 t/ha dose had the highest germination rate. An increase in yield of all crops during the whole duration of the experiment was observed for the soil amended by phosphogypsum. The best yield was recorded when the highest dose of phosphogypsum was applied. The cadmium level in plants of the two applied amendments was variable but still below the toxicity threshold (7 ppm). The values recorded following the analysis of the phosphogypsum radioactivity showed that the mean value of Ra-226 equals 214.45 Bq/kg, which is below the limit announced by the EPA (Environmental Protection Agency). The radioactivity results from the control soil samples showed the presence of natural radioactivity. Samples of phosphogypsum-amended soil and plants grown in these soils have radioactivity values that are still lower than those announced by the EPA. The novelty aspect of this study is the application of phosphogypsum in different crops during two consecutive years in degraded-soil areas of Tunisia, in addition to the study of different aspects of phosphogypsum reuse in agriculture as a promising strategy for a sustainable environment.

Agroecological Transformation in the Salt Composition of Soil under the Phosphogypsum Influence on Irrigated Lands in Ukraine

“…Long-term studies [70,71] have shown that the application of phosphogypsum on irrigated saline chernozem soils has a positive effect on the anion-cation composition of water leaching and the degree of salinity of these soils [72,73]. In experimental plots, with the application of phosphogypsum during irrigation and without it, a sulphate type of salinity was observed in terms of the anion composition.…”

Bioremediation of Modified Phosphogypsum to Cultivable Anthrosol via Peanut Growth

“…It is rich in vital nutrients like phosphorus, calcium, magnesium, and more, which can reduce the need for additional fertilizers . Other benefits include eliminating the surface crust of the soil, reducing the viscosity of the soil, increasing the permeability of the soil , and increasing yield while preventing certain crop diseases. − Phosphogypsum has been used to improve acidic soil by Villalón Fornés et al and have been tested corn pot planting experiments by Carvalho et al . Its positive effects on soil structure have been well-documented, such as promoting flocculation between soil particles and enhancing soil aggregation .…”

“…The variability complicates the development of a universal purification method. However, bioremediation emerges as a beacon of hope in this scenario. , It effectively uses organisms to absorb, transform, or immobilize contaminants, offering adaptability and environmental compatibility . Its efficacy is underscored by successes such as the extraction of heavy metals from phosphogypsum in Florida, a region notorious for its high radioactive content in phosphogypsum…”