Microalgal amendments can improve soil structure by regulating extracellular polymeric substances (EPSs). However, the mechanisms underlying this process in red soils (characterized by high clay content and susceptibility to acidification) under different farming practices remain unclear. This study examined how Chlorella vulgaris (C. vulgaris) amendment influences EPS composition to enhance soil aggregate stability under arable land and rice paddy farming. A five-month pot experiment using a completely randomized design was conducted to investigate the effects of Chlorella vulgaris amendment on soils cultivated with Pennisetum × sinese and rice, two economically important crops commonly grown in South China. At the end of the experiment, Chlorella vulgaris amendment substantially increased both the mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates under both farming systems. Excitation–emission matrix (EEM) fluorescence spectroscopy revealed distinct changes in soil EPS components between the two farming types. Under arable land farming, humic-like and protein-like EPSs were dominant in Chlorella vulgaris-amended treatments, with fluorescence intensities more than doubling compared to the control. Conversely, under rice paddy farming, soil fulvic acid was the main component and showed a moderate increase. Partial least squares path modeling (PLS-PM) demonstrated that protein-like and humic-like EPSs had the strongest direct effects on aggregate stability in arable land red soil, while fulvic acid was the key factor in rice paddy red soil. The present study demonstrates that Chlorella vulgaris amendment improves aggregate stability in red soils through farming-specific, EPS-mediated pathways, providing a quantitative framework for researchers and land managers seeking to apply microalgal amendments for red soil enhancement and sustainable land management.

Introduction This study aimed to investigate the effects of nitrification inhibitors (NIs), specifically DMPP (Dimethyl pyrazole phosphate) and DMPFA (Dimethyl pyrazole fulvic acid), and plant growth-promoting microorganisms (PGPM) on nutrient uptake, allocation, and plant growth in maize under low phosphorus (P) availability. The research questions explored whether NIs enhance P, manganese (Mn), and zinc (Zn) uptake through rhizosphere acidification, alter nutrient partitioning between roots and shoots, and whether DMPFA-PGPM combinations synergistically improve plant growth and nutrient acquisition. Methods Two rhizobox experiments were conducted using silt loam soil with low P content (8.7 mg kg −1 P-CAL, pH 6.4). Results In the first experiment, maize was subjected to ten treatments, including ammonium (NH 4 + ) and nitrate (NO3 −) with or without DMPP, DMPFA, and rock phosphate (RP), compared to controls. The second experiment tested five treatments, including NH 4 + with DMPFA, fulvic acid, and Bacillus atrophaeus (ABi05) as PGPM. Measurements included rhizosphere pH, acid/alkaline phosphatase activity, root exudates, phytohormones, root morphology, plant biomass, and nutrient (P, Mn, Zn, Fe, Ca, Mg, K) concentrations in shoots and roots. Nutrient use efficiencies (PUE, PFPp, NRE) were calculated, and data were analyzed using one-way ANOVA with Fisher’s LSD test (p<0.05). In the first experiment, DMPP+RP and DMPFA+RP treatments increased biomass by 31.8% and 38.5%, respectively, compared to the negative control, with total root length rising by up to 169.5% in the positive control (NO 3 −+soluble P). Shoot Fe content was 60% higher in NI treatments, with Mn and Zn shoot concentrations increasing by up to 40.4% and 32.8%, respectively, in DMPFA treatments. The rhizosphere pH dropped by 0.5 units in NI treatments, thereby enhancing acid phosphatase activity. In the second experiment, DMPFA and DMPFA+ABi05 increased shoot biomass by 47.5% and 50.7%, respectively, and shoot P content by 45.1% and 62.7%. PUE was 56.2% higher with DMPFA+ABi05, and zeatin concentrations rose by 79.1% compared to controls. Conclusion DMP-based NIs significantly enhance P, Mn, and Zn uptake in maize by acidifying the rhizosphere and increasing nutrient solubility. NIs shift mainly Fe and Mn allocation toward shoots, improving nutrient mobilization. The synergistic effect of DMPFA and PGPM (ABi05) further boosts PUE and Zeatin.

Biostimulants are increasingly recognized in modern agriculture as eco-friendly inputs that enhance plant growth, improve stress tolerance, and promote product quality. This study investigated the effects of fulvic acid, amino acids, and chitosan on the growth, yield, and nutritional quality of parsley grown under hydroponic greenhouse conditions. The research was conducted in two stages. In the first stage, different doses of fulvic acid (80–120 ppm), amino acids (40–80 ppm), and chitosan (0.3–0.6 mL L−1) were evaluated. In the second stage, the most effective treatments were tested in combination. The results showed that all biostimulants positively influenced plant growth, productivity, and nutritional parameters. In the first experiment, the highest total yield was obtained with chitosan at 0.3 mL L−1 (2068 g m−2; +30.1%). The greatest increase in total phenolic content was observed with AA 40 (391.1 mg GA 100 g−1 FW; +64%), while the strongest nitrate reduction occurred with FA 120, reducing nitrate levels from 1048 to 405 mg kg−1 (−61%). In the second experiment, the FA 80 + C 0.3 combination was the most effective treatment, increasing total yield from 493 to 856 g m−2 (+73.7%) and reducing nitrate content from 937 to 460 mg kg−1 (−50.9%). These findings suggest that fulvic acid and chitosan, applied individually and particularly in combination, may serve as effective biostimulant strategies for improving yield and nutritional quality while reducing nitrate accumulation in hydroponically grown parsley.

Elucidating the mechanism of fulvic acid-mediated PCR inhibition and its mitigation through nanoparticle-assisted amplification.

Association of naturally occurring radionuclides with organic matter in soils in Mediterranean ecosystems.

Fulvic acids act as chemical eustressors driving redox and hormonal reprogramming in rice roots.

One-step microwave fabrication of waste potato-derived bifunctional film: sustainable mulch-fertilizer for plastic substitution.

Accelerated transformation of 6PPD to 6PPD-Q in tire wear particles driven by roadway manganese oxides and dry-wet cycles: Interfacial catalysis coupled with climatic stressors.

Molecular transformation and photochemical reactivity of microplastic-derived dissolved organic matter on goethite: Implications for persistence and reactive oxygen species dynamics.

Spatio-temporal distribution and production-consumption dynamics of nitric oxide in coastal waters off Qingdao, China.

Schematic representation of the conversion of LRCs to humic substances.

Bioremediation of oligotrophic waters by fulvic acid-modified bio-immobilized materials coupled with microbial-induced calcium precipitation: Performance and mechanism.

Efficient adsorption and degradation of Di-(2-ethylhexyl) phthalate (DEHP) by Nanomaterial-modified biochar: Insights into microbial communities, functional genes, and metabolic pathways.

Straw interlayer burial improved soil humic fractions via pore-microbe mediated life strategy hierarchy regulating pore structure and bacterial characteristic in saline soils.

Shilajit extract (ZhaXun) protects against acetaminophen-induced liver injury via modulation of the NF-κB/AKT/Caspase-3 axis.

Electrochemical decomplexation of Cu(II)-citrate and copper recovery via peroxymonosulfate activation with N,O co-doped carbon felt cathode.

Addition of chemical oxidation catalysts accelerates heating and humification in biodrying-enhanced composting process for kitchen waste.

Phosphorus speciation using ion chromatography coupled with ICP-MS elucidates transformations of phosphorus compounds on reactive surfaces.

Synergistic photocatalysis of BiOCl/MXene activates peroxymonosulfate for enhanced fulvic acid degradation: performance and mechanism insights

Improving the depression selectivity of fulvic acid for the efficient upgrading of phosphate ores based on nitrification modification: Flotation performance and mechanism insights