Physicochemical Characterization and Application of Cow Manure Biochar as a Substrate for Halophyte Growth and Coastal Soil

The physicochemical properties and applicability of cow manure biochar (CMB) as a soil conditioner and horticultural substrate amendment for halophyte growing on deteriorated coastal soils were assessed in this study. A typical commercial substrate (50% coco peat, 25% peat moss, 12% perlite, 7% vermiculite, and 6% zeolite) was used to compare elemental composition, thermal stability (TGA/DTG), surface morphology, pore structures (BET, FESEM), and functional groups (FT-IR) of CMB. In addition, 10% (w/w) CMB was added to coastal soils in the Saemangeum and Sinan-gun regions in order to assess changes in the physicochemical soil quality. In comparison to the commercial substrate, the analytical results showed that CMB had higher concentrations of essential mineral elements (such as K, Ca, P, Zn, and Na), a higher proportion of carbon (25.69%), and more accessible phosphorus (3490.97 mg/kg). Additionally, compared to the commercial substrate, CMB showed a nearly 19-fold larger specific surface area (77.53 m2/g) and increased micropore volume, suggesting better potential for soil aeration and water retention. Cultivating halophytes (Salicornia herbacea L. (glasswort) and Suaeda japonica Makino (seepweed)) in a 9:1 (v/v) substrate-to-CMB mixture for five weeks resulted in successful early germination and robust seedling establishment. Incorporating 10% CMB into coastal soils also substantially increased available phosphorus, total organic carbon (TOC), and organic matter (OM), demonstrating CMB’s effectiveness in enhancing nutrient availability and supporting soil carbon sequestration. All things considered, this study offers a practical framework for using biochar made from livestock manure as a sustainable substrate supplement to reclaim degraded coastal environments and advance biosaline agriculture.