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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 recei...

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Published in:Environmental technology & innovation 2021-11, Vol.24, p.101867, Article 101867
Main Authors: Kong, Chao, Camps-Arbestain, Marta, Clothier, Brent, Bishop, Peter, Vázquez, Felipe Macías
Format: Article
Language:English
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Summary: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 °C/ 16 ± 1 °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−1d−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. •Our studies emphasised the benefits of applying pumice to alleviate salinity and sodicity stress in plants.•The benefits of pumice were amplified when this was added along with algae (at a 2% v/v).•Pumice-induced salt trapping could be explained by a breaking of the hydraulic connections within the water column, induced by the formation of entrapped air blocks in the pores during desiccation.
ISSN:2352-1864
2352-1864
DOI:10.1016/j.eti.2021.101867