Preparation and characterization of eco-friendly polysaccharide-based liquid mulch with soil amendment function

Abstract

Plastic pollution and soil degradation pose substantial threats to the ecosystem. The need for a cleaner environment and a protector of degraded soil is urgently calling for a green alternative to petroleum-based plastic mulch . Here, we prepared a polysaccharide-based liquid mulch with soil amendment function by an emulsification method, which was used as a sprayable and green alternative to the petroleum-based plastic mulch and a soil remediation agent for degraded soil. Tamarind polysaccharides from tamarind industrial waste was applied as the film-forming agent and the soil particle aggregator . Additionally, Camellia saponins — the natural surfactant, and regenerated oil from waste cooking oil were added to the mulch to improve its homogeneity , mechanical property and hydrophobicity . By just adding 1% of regenerated oil to the system, the elongation at break and contact angle notably increased from 43.97% to 74.46% and 47.00°–86.82°, respectively; the water-vapor permeability of the liquid mulch reduced from 5.63 g⋅mm⋅h −1 ⋅kPa −1 ⋅m −2 to 1.76 g⋅mm⋅h −1 ⋅kPa −1 ⋅m −2 . Application tests showed that the polysaccharide-based liquid mulch effectively achieved a high rate of soil resistance (90.36%) to wind erosion. Topsoil erosion caused by wind can be considerably reduced. Scanning electron microscopic characterization revealed the effect of xyloglucan on soil particle aggregation. The liquid mulch also increased the germination rate by 31.00%. Moreover, after liquid mulch degradation, the nitrogen and carbon contents of the soil increased significantly from 0.05% to 0.60% and 1.42%–13.54%, respectively, thereby substantially increasing the soil organic matter content. The developed low-cost, yield-improving liquid mulch shows promising prospects for mulches and soil amendment in agriculture. • The liquid mulch was predominantly made from industrial wastes. • The preparation method is green, clean, simple, and cost-effective. • The liquid mulch improved water retention and effectively promoted soil aggregation. • Soil C and N contents were notably increased after the liquid mulch degradation. • The liquid mulch is greatly degradable and eco-friendly.