EVALUATION OF THE POTENTIAL OF PHOSPHOGYPSUM FOR IMPROVING SOIL STRUCTURE & CROP YIELD

BSc. Samuel Dotun Oyekunle, BSc

Diplomová práce

Abstract:

Soil degradation, driven by salinization, sodicity, and structural deterioration, remains a critical threat to global agricultural productivity, particularly in irrigated farming systems across sub-Saharan Africa and other vulnerable regions. Phosphogypsum (PG), a calcium sulphate-rich industrial by-product of phosphoric acid production, has been identified as a promising and cost-effective amendment for ameliorating degraded soils. However, systematic, site-specific evaluation of its optimal application rate and concurrent effects on soil physical and chemical properties and crop productivity remains limited. This study evaluated the potential of Phosphogypsum to improve soil structural properties and enhance crop yield under controlled pot conditions, using four PG application rates of 1 g kg⁻¹, 5g kg⁻¹, 10g kg⁻¹, and 15g kg⁻¹ alongside an unamended control. Key soil parameters assessed included bulk density, gravimetric soil moisture content, soil pH, and electrical conductivity, while plant growth was evaluated using root and shoot lengths, fresh and dry weights, and root-to-shoot ratios at 1 and 2 weeks after planting. The results showed that PG application had mostly positive effects on soil chemical properties and plant growth, with the response strongly dependent on the application rate and observation period. Soil pH decreased significantly in all PG-treated soils, indicating the acidifying effect of calcium sulphate dissolution and its interaction with soil alkalinity. Electrical conductivity increased gradually with higher PG rates, aligning with the expected short-term rise in soluble ions after amendment. Soil moisture retention improved noticeably in PG-treated soils two weeks after planting, surpassing the unamended control and suggesting ongoing structural reorganization driven by calcium-sodium exchange. Soil bulk density showed no statistically significant change over the experimental duration, likely due to soil sieving and the constraints of the pot-based setup. The 1 g kg⁻¹ PG rate was identified as the optimal dose, yielding the highest shoot length, fresh weight, and dry weight, whereas the 5g kg⁻¹ rate exhibited early signs of growth inhibition due to salinity. These findings confirm the potential of Phosphogypsum as a versatile soil amendment and underscore the need to optimize the rate to maximize benefits without harming soil health.

Keywords

Phosphogypsum, Sustainable Soil Management, Saline-sodic soil reclamation, Soil physiochemical properties, Calcium Sulphate amendment

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 26. 4. 2026

Obhajoba závěrečné práce

• Obhajoba proběhla 2. 6. 2026
• Vedoucí: doc. Ing. Hynek Roubík, Ph.D.
• Oponent: Nils Haneklaus

Česká zemědělská univerzita v Praze

Fakulta tropického zemědělství

Magisterský studijní program:
Tropical Crop Management and Ecology