While rhizosphere microbiome functions in saline soils are well documented, complementary microbial strategies between pioneer and late-successional halophytes remain unexplored. Here, we used 16S rRNA sequencing and FAPROTAX functional prediction to compare the rhizosphere bacterial communities of two key halophytes—Suaeda glauca and Phragmites communis—in a reclaimed coastal wetland. The results demonstrate that both plants significantly restructured microbial communities through convergent enrichment of stress-tolerant taxa (Firmicutes, Pseudomonas, Bacillus, and Planococcus) while suppressing sulfur-oxidizing bacteria (Sulfurovum and Thiobacillus). However, they exhibited distinct microbial specialization: S. glauca uniquely enriched organic-matter-degrading taxa (Promicromonospora and Zhihengliuella) and upregulated aromatic compound degradation (2.29%) and ureolysis (0.86%) according to FAPROTAX analysis, facilitating carbon mobilization in early successional stages. Notably, P. communis selectively recruited nitrogen-cycling Serratia, with increased nitrate respiration (3.51% in P. communis vs. 0.91% in S. glauca) function, reflecting its higher nitrogen demand. Environmental factors also diverged: S. glauca’s microbiome correlated with potassium and sodium, whereas P. communis responded to phosphorus and chloride. These findings uncover distinct microbial recruitment strategies by halophytes to combat saline stress—S. glauca–P. communis synergy through microbial carbon-nitrogen coupling—offering a template for consortia design in saline soil restoration.

Amending saline–alkali soils to improve agricultural productivity is critical for addressing global food security challenges. Biochar is a promising soil amendment, and its modified composites offer significant potential for soil remediation. In this study, we developed a novel phosphoric acid–mineral-comodified biochar composite for saline–alkali soil improvement. SEM and XRD analyses indicate that chemical interactions between phosphoric acid, minerals, and biochar result in the formation of distinct mineral phases on the composite surface. Furthermore, FTIR analysis reveals that these interactions give rise to functional groups such as Si-O-Si, and thermogravimetric analysis demonstrates that the modified biochar composite exhibited enhanced stability. Compared with raw biochar, the modified biochar composites exhibited significant decreases in pH, EC, and base cation content (especially Na⁺), with maximum reductions of 7.26 pH units, 639.5 μS/cm, and 3.69 g/kg, respectively. In contrast, the contents of P, Si, and Ca increased significantly, with maximum increases of 140.04 g/kg, 90.32 g/kg, and 114.27 g/kg, respectively. In addition, the specific surface area and pore volume of the modified biochar composite increased by up to 5.2 and 15 times, respectively. Principal component analysis indicates that mineral type was the primary factor influencing the properties of the composites: hydroxyapatite enhanced porosity and phosphorus levels, whereas kaolinite and montmorillonite increased silicon content. Pot experiments show that the modified biochar composite increased alfalfa plant height by 17.36–20.27% and shoot biomass by 107.32–125.80% in saline–alkali soils. Overall, the newly developed phosphoric acid–mineral–biochar composites were evaluated to have high application potential for saline–alkali soil amendment.

Large amounts of residues are generated in pecan cultivation processes. Biochar is an environmentally friendly way to utilize residues but attempts to prepare and apply biochar with pecan residues are rare. In this study, six types of biochars were produced from pecan branches, trunks, roots, nutshells, husks, and leaves under pyrolysis, and their physicochemical properties were compared to assess their application perspective in environmental and agricultural fields. The yields of six pecan biochars were 32.1%–45.9%, with the highest yield for husk biochar (HB) (45.9%). Among the pecan biochars, trunk biochar (TB) and root biochar (RB) had much larger specific surface areas. Branch biochar (BB), TB, and RB presented tubular structures with elliptical pores, while nutshell biochar (NSB), HB, and leaf biochar (LB) appeared flaky or as clustered structures with relatively rougher outer surfaces and irregular pores. The functional group types of pecan biochars were generally similar, but the intensities of the peak near 2900 cm⁻¹ in BB were obviously higher than those of the other biochars. RB and LB contained significantly more ash and volatile than those of the other pecan biochars, with the highest fixed carbon content being found in NSB (70.1%). All of the pecan biochars were alkaline (7.90–9.87), and HB, LB, and NSB had significantly higher pH values than those of the other biochars. Elemental analysis indicated that RB, NSB, and LB had higher carbon levels (more than 70%) with lower O/C ratios (no more than 0.2). HB possessed a relatively high content of nitrogen, potassium, magnesium; the phosphorus content was highest in NSB; LB had the highest calcium content. The results of principal component analysis showed that BB, LB, and NSB were clustered in the same quadrant with relatively close relationships. The results of this study can guide the utilization of pecan wastes and their application as biochar in different fields.