Reclamation of salt-affected soils using pumice and algal amendments: Impact on soil salinity and the growth of lucerne

We investigated whether individual or combined additions of either pumice (PU) and/or algae (AL) to a sandy soil could alleviate the impact of irrigation with saline water on the growth of lucerne (Medicago sativa L.) under simulated semi-arid conditions. The study included six treatments that received saline water (6.4 dS m(-1)): T1 (sand - positive control), T2 (sand + 3% (v/v basis) PU), T3 (sand + 12% PU), T4 (sand + 3% PU + 2% AL), T5 (sand + 12% PU + 2% AL), T6 (sand + 2% AL). A seventh treatment was T7 (sand - negative control), to which deionised water was added. All treatments underwent 14 cycles of irrigation wetting and drying events (at 27 +/- 1 degrees C/16 +/- 1 degrees C day/night). At the end of the experiment and compared with the positive control (T1) (EC: 2.3 dS m(-1); SAR: 21.8), the two treatments with the largest application rate of PU (T5 and T3) showed the largest (significant at P < 0.05) reduction in soil EC, SAR, and water-extractable ions among those treatments receiving saline water (T1-T6). Lucerne in treatments T1-T6 always had a smaller dry weight (DW) biomass and relative growth rate (RGR) than the treatment receiving deionised water (T7) (DW: 2.29 g m(-2); RGR: 0.073 mg g(-1) d(-1)), but values for treatment T5 (DW: 1.69 g m(-2); RGR: 0.06 mg g(-1)d(-1)) were significantly larger (P < 0.05) than for treatments T1-T4 and T6 (DW < 1.13 g m(-2); RGR < 0.056 mg g(-1) d(-1)). Overall, the results obtained suggest that, if proven feasible at a field scale, the combined addition of PU (12%), by reducing salinity and contributing to water retention, and AL (2%), by adding nutrients and/or bioactive compounds, could be used to mitigate salt stress and improve plant growth in sandy soils under arid conditions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the individual or combined effects of pumice (PU) and algae (AL) on alleviating the impact of saline water irrigation on lucerne growth in sandy soil under simulated semi-arid conditions. Results showed that the treatments with higher PU application rates had significant reductions in soil salinity and water extractable ions. Overall, the combined addition of PU (12%) and AL (2%) could effectively mitigate salt stress and improve plant growth in sandy soils under arid conditions.