In arid regions, decreased soil fertility has adversely affected agricultural sustainability. The effects of different amendments in alleviating these issues and increasing soil fertility remain unclear. Herein, a two-year field experiment was conducted to evaluate the properties of grey desert soil and soil respiration (SR) dynamics under six different treatment groups: biochar (BC), leonardite (LD), anionic polyacrylamide (PAM⁻), cationic polyacrylamide (PAM⁺) powder, anionic polyacrylamide solution in water (PAM⁻W), and control (CK). We observed that the BC and LD amendments significantly altered soil pH, organic matter, available nitrogen, available phosphorus, cation exchange capacity, and SR. PAM amendment increased the SR as compared to the control, except in autumn, but PAM did not affect the soil properties. SR under different amendments showed strong seasonal patterns, the highest and lowest SR rates were observed in June and January, respectively. Amendments and seasonal dynamics significantly affected SR, but no interaction was observed between these factors. Temporal variation of SR was substantially influenced by soil temperature at 15 cm of soil depth. Temperature sensitivity of SR (Q₁₀) increased with soil depth and decreased with amendment addition. SR was significantly affected by soil temperature, moisture, air temperature, and their interactions. The outcomes of this study suggested that the BC and LD amendments improved soil fertility and negated the net carbon accumulation by increasing the SR and Q₁₀ in arid agriculture soil.

We evaluated the diagnostic and predictive performance of the coupled General Ocean Turbulence Model–Framework for Aquatic Biogeochemical Models–Water Ecosystems Tool (GOTM–FABM–WET) in shallow Kun Cheng Lake, China. Monthly near-surface observations supported model calibration during 2021–2023 and out-of-sample ecological validation during 2024–2025. Model skill was assessed through one-at-a-time parameter screening, moment-independent Delta sensitivity analysis with sample-size convergence diagnostics, sequential multi-parameter calibration, and comparisons against statistical and nutrient mass-balance benchmarks. Water temperature calibration was strong (Nash–Sutcliffe efficiency, NSE = 0.933), although temperature observations were available only for 2021–2023. Dissolved oxygen (DO) exhibited modest validation skill (NSE = 0.290). Nitrogen parameter refinement improved correlation direction and simulated variability, yet the simulated seasonal TN peak remained five months earlier than observed. Total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chl-a) all retained negative validation NSE values. In particular, Chl-a calibration remained inadequate (calibration NSE = −0.405; validation NSE = −0.481), and its dedicated calibration stage retained the incoming seed parameters. Only 0.50–0.78% of evaluated candidates satisfied the cross-variable calibration guardrails. Temporally constant nutrient boundaries, coarse TP reporting resolution, and frequent numerical state repairs highlight key priorities for model improvement. Overall, the current evidence supports retrospective near-surface thermal diagnosis and conditional interpretation of broad seasonal DO patterns, whereas reliable nutrient and algal prediction will require time-varying inflow and nutrient chemistry, process-level field observations, and independent verification of seasonal timing and spatial representativeness.