Effect of phosphogypsum application rates and methods on the performance of sorghum ( Sorghum L.) and selected chemical properties of saline–sodic soil

Abstract Phosphogypsum (PG) can recoup saline–sodic soil problems, however, its effectiveness in the central rift valley (CRV) of Ethiopia remains understudied. A two-season field experiment was conducted in Metehara to evaluate PG rates and methods of application on the performance of sorghum on saline–sodic soil in CRV. A split plot design with four replications was employed. Two application methods (band and broadcast), and six treatments (five PG rates: 0, 50, 100, 150, 200% GR (gypsum requirement), and common grade gypsum were randomly assigned as main and subplots, respectively. After harvest, soil (0–20 cm) samples were collected from each plot and analyzed following standard laboratory procedures. Results showed that PG at 150% GR significantly ( p < 0.001) reduced soil EC (34.10–7.08 dSm −1 ), pH (9.60–7.20), Na + (29.64–7.36 cmol kg −1 ) and ESP (59.52%–10.70%) under banded plots. Whereas, PG at 150%–200% GR significantly ( p < 0.01) enhanced soil P, %N, SO 4 2− and Ca 2+ level in banded plots. Sorghum biomass and grain yields were increased from 4642 to 16 452 kg ha −1 and 476.8–4284.2 kg ha −1 at 150%GR, respectively under banded PG. Broadcasted plots also improved the soil properties and sorghum yield, but less effectively. Overall, banded PG at 150%GR optimally reclaims saline–sodic soil of Metehara, improved sorghum productivity. Further validation across similar agro-ecologies is recommended.