Plastic film buried in a low-lying strongly salt-affected wasteland: An effective desalinization approach should not be ignored for Amorpha fruticosa afforestation

Cutting off the upward movement of salts by capillary barriers may be an effective approach to control the root-zone salt accumulation in a low-lying salt-affected wasteland with high evaporation. This study aimed to determine whether buried plastic film (BPF), as an ignored desalinization approach, could better sustainably ameliorate salt-affected soil environment especially soil salinity than common capillary barriers (buried maize straw, BMS; buried sand, BS) and CK (a control without buried material) during Amorpha fruticosa afforestation. All the capillary barriers especially BPF effectively reduced electrical conductivity of saturated paste extracts (ECe) compared to CK in both years mainly due to its greater effectiveness of salts isolation, and gravitational washing increasingly via more preferential pathways indicated by its higher fine-root mass density (FRMD). Capillary barriers varyingly improved the fertility and structure in different soil layers. BPF reduced soil organic carbon (SOC) in 0–20 cm most in 2016, but increased it most in 2017; while BMS increased SOC in 20–40 cm most in both years. In both years, available nitrogen (AN) in 0–20 cm increased most for BPF, while AN in 20–40 cm did for BMS. Similarly, BPF improved better in soil structure (mean weight diameter, MWD; soil total porosity, STP) in 0–20 cm while BMS did in 20–40 cm. As the salinity declined, BPF was more beneficial to the stand establishment and plant growth which in turn further bio-physicochemically improved salt-affected soil environment. BPF was not only far less costly than BMS or BS, but also obviously produced more yield and thus greater net revenue in the second year. Thus, BPF is a promising alternative for desalinization during the afforestation of salt-tolerant plants in the similar strongly salt-affected areas.