Evaluating the effect of phosphogypsum source and rate on barley yield components, nutrients uptake, and heavy metals content under saline conditions

Soil salinity is a major factor in land degradation, affecting one billion hectares worldwide. Several strategies for overcoming salinity stress have been tested. Using inorganic amendments, such as phosphogypsum (PG) and natural gypsum (G), is one of the promising strategies for salinity mitigation. A pot trial was conducted, under greenhouse conditions, using a saline soil (ECe soil = 11.7 dS m−1) and barley (Hordeum vulgare) as an indicator crop. We aimed to evaluate the effects of different sources of PG on soil salinity mitigation in comparison with G and consequently on barley yield components and metal uptake. Three treatments were tested: two phosphogypsum sources from two different phosphate industrial sites (PG1 and PG2), applied at four rates (0, 15, 30 and 45 t ha−1) and natural gypsum at one rate (15 t ha−1). Results showed that the weight and number of spikes and tillers, grain yield, and 1000-grain weight were all affected by the rate of PG, but not by PG source. The PG1 and PG2 enhanced the grain yield by 61% and 59% respectively, across rates compared to the control (0 t ha-1). Shoot and grains nutrients uptake were enhanced by PG addition with no effect on heavy metals contents of barley’s grains and shoots. Phosphogypsum appeared to be more efficient in promoting barley yield and nutrients uptake compared to G at 15 t ha-1. For instance, the grain yield, and the uptakes of P, S, K, and Mg were 11%, 100%, 64%, 70%, and 75% greater, respectively, across PG sources compared to G. This study confirmed that PG is beneficial for saline soils remediation and fertilization and can replace natural gypsum.