Published in PLOS One on 2026-09-11, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: Kebenu Feyisa Gonfa, Kibebew Kibret Tsehai, Sheleme Beyene Jiru, Lemma Wogi Mirkena
Source: PLOS One • DOI 10.1371/journal.pone.0345688
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
Soil salinity and sodicity are among the major challenges threatening agricultural productivity in the Central Rift Valley of Ethiopia. A column experiment was conducted in laboratory on saline-sodic soils of Metehara Sugar Estate to evaluate the effectiveness of phosphogypsum and leaching in reclaiming these soils. The treatments comprised of five rates of phosphogypsum equivalent to 50, 75, 100, 150, and 200% gypsum requirement, 100% gypsum requirement of natural gypsum, and an absolute control with no amendments applied, and five volumes of leaching water. The treatments were arranged in Complete Randomized Design with three replications. The leaching water was applied to the columns in an intermittent ponding mode. Leachates and soil samples collected from the columns after termination of the leaching process were analyzed for selected soil properties. Results showed that applying phosphogypsum at a rate of 100% gypsum requirement or higher (which is equivalent to ≥ 13 tons/ha) along with 3–4 pore volume of leaching water was found to be the most effective combination to reduce salinity and sodicity to levels that are suitable for most crops (ECe < 4 dS/m and ESP < 10%,). The efficiency of phosphogypsum equivalent to 200% gypsum requirement was 81% and 75% in soluble salt removal and Na reduction, respectively. Results of the study suggest that phosphogypsum is a promising reclamation material for saline-sodic soils. However, a greenhouse and field experiments have to be conducted to evaluate the effectiveness of these amendments under controlled and natural conditions and come-up with implementable rate recommendations.
1. Introduction
Soil degradation, which is driven by human activities [1,2] and deteriorates soil quality [3], is a critical global issue, with negative consequences on the amount of arable land and food security. Salinity and sodicity, which lead to the formation of salt-affected soils, are among the major forms of chemical soil degradation that pose a serious threat to agricultural productivity globally [3].
Ethiopia, where over 60% of its territory lies in arid and semiarid regions, is among the African countries that are mostly affected by salinity [4]. Empirical evidences indicate that nearly 44 million hectares (36% of the total land area) of the country’s land is potentially vulnerable to salt problems. Out of these 11 million hectares are already affected by varying degrees of salinity and sodicity, with most of these areas concentrated in the Rift Valley [5,6]. These figures make Ethiopia, the country with the highest percentage of salt-affected land in Africa and the 7th highest globally. As a result, its irrigated lands are threatened by reduced productivity, resulting in increased food insecurity in those regions [6,7].
For sodic and saline-sodic soils, chemical amendments are inevitable options for replacing exchangeable sodium. These amendments, most of which are typically calcium-bearing materials or acids, aim to replace sodium with calcium and improve soil structure. The chemical amendments should be accompanied by leaching to remove the replaced sodium and excess salts from the soil solution [8,9]. Effectiveness and cost determine the choice of the best chemical amendments [10]. In connection with this, several studies [e.g., 11–13] reported the superiority of phosphogypsum (PG), a byproduct of a fertilizer industry, to the commonly used mined gypsum.
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider research & evidence desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 Kebenu Feyisa Gonfa, Kibebew Kibret Tsehai, Sheleme Beyene Jiru, Lemma Wogi Mirkena. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
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