Fulvic acids (FAs) improve the structure and fertility of soils with varying textures and also play a crucial role in increasing crop production. The pot experiment was carried out using wheat grown on three soils with a silty clay, sandy loam, and clay loam texture, respectively. The soils were treated with FAs derived from plant and mineral materials. Plant-derived solid (PSFA), mineral-derived liquid (NLFA), and plant-derived liquid (PLFA) were applied at a rate of 2.5, 5, and 5 g kg⁻¹ and control applied at 0 g kg⁻¹. The results showed that in treated soils, the heavy fraction C was higher by 10%–60%, and the light fraction C increased by 30%–60%. Similarly, the available N content significantly increased in treated soils by 30%–70% and the available K content increased by 20%–45%, while P content significantly increased by 80%–90% in Aridisols and Vertisols and decreased by 60%–70% in Mollisols. In contrast, for P, the organic–inorganic compounds were greater in Aridisols and Vertisols and lower in Mollisols. However, organic–inorganic composites decreased in Vertisols relative to the other two soils. Further results showed that PSFA and NLFA accelerated the plant growth parameters in Mollisols and Aridisols, respectively. Our study demonstrates that the application of PSFA and NLFA had a positive effect on the physical and chemical properties and plant growth characteristics of Mollisol and Vertisol soils. Moreover, the application of solid-state FA yields better results in Mollisols. However, liquid FA increases the nutrient availability and the effects on the chemical, biological, and physical properties of Aridisol and Vertisol soils.

The application of an acidic biochar can improve plant growth and soil properties in saline conditions. In this study, we investigated the effect of acidic biochar on plant growth and nutrients contents in saline soil. Seven treatments were arranged in a complete randomized design, including control (CK), 0, 30, and 45 g biochar added to a soil having 1% and 1.5% salts; these treatments were termed as B₀S₁, B₃₀S₁, B₄₅S₁ and B₀S_1.5, B₃₀S_1.5, B₄₅S_1.5 respectively. Experimental results showed that the plant height, leaves plant⁻¹, leaf area, and shoot fresh and dry biomass, and root fresh and dry biomass were increased for the B₄₅S_1.5, respectively. Similarly, the highest total nitrogen (TN), total phosphorus (TP), total potassium (TK), and total sodium (Na) concentration in maize shoot were observed for B₃₀S₁, B₀S_1.5, CK, and B₀S_1.5, respectively. The highest concentrations of TN, TP, TK, and Na in root were obtained with the treatments B₀S₁, B₀S₁, B₄₅S₁, and B₀S₁, respectively. Soil pH, and EC decreased and nutrients concentration improved by the addition of acidic biochar. We conclude that the use of acidic biochar can be a potential source for the improvement of maize plant growth as well as mitigate the adverse effect of salt stress.

Soil salinization adversely affects agricultural productivity. Mitigating the adverse effects of salinity represents a current major challenge for agricultural researchers worldwide. The effects of exogenously applied glycine betaine (GB) and salicylic acid (SA) on mitigating sodium toxicity and improving the growth of cotton seedlings subjected to salt stress remain unclear. The treatments in a phytotron included a control (CK, exogenously untreated, non-saline), two NaCl conditions (0 and 150 mM), four exogenous GB concentrations (0, 2.5, 5.0, and 7.5 mM), and four exogenous SA concentrations (0, 1.0, 1.5, and 2.0 mM). The shoot and roots exposed to 150 mM NaCl without supplementation had significantly higher Na⁺ and reduced K⁺, Ca²⁺, and Mg²⁺ contents, along with lowered biomass, compared with those of CK. Under NaCl stress, exogenous GB and SA at all concentrations substantially inversed these trends by improving ion uptake regulation and biomass accumulation compared with NaCl stress alone. Supplementation with 5.0 mM GB and with 1.0 mM SA under NaCl stress were the most effective conditions for mitigating Na⁺ toxicity and enhancing biomass accumulation. NaCl stress had a negative effect on plant growth parameters, including plant height, leaf area, leaf water potential, and total nitrogen (N) in the shoot and roots, which were improved by supplementation with 5.0 mM GB or 1.0 mM SA. Supplementation with 5.0 mM exogenous GB was more effective in controlling the percentage loss of conductivity (PLC) under NaCl stress.

The application of organic manure/substances in soil can directly alter soil structure and influence the soil organic carbon (SOC), soil aggregate stability, and aggregate-associated nitrogen (N).

Background: Soil erosion not only leads to soil loss but also redistributes soil organic carbon (SOC) and releases carbon dioxide (CO ₂ ) that contributes significantly to regional carbon emissions. Great efforts have been made to prevent soil erosion in the Yellow River Basin (YRB) in China in the past decades. Only few studies have paid attention to carbon emissions from soil loss. This study integrates the China Soil Loss Equation (CSLE) with a transport-limited sediment delivery (TLSD) model to quantify sediment redistribution and associated carbon emissions across five depositional processes (slope, reservoir, plain, river channel, and regional output) in the YRB. Results: The CSLE-TLSD model calibrated to a significantly improved Nash-Sutcliffe efficiency of 0.5690, compared to 0.5628 for the CSLE model. Results reveal that 28.50 ± 4.43% of eroded SOC was decomposed during transport, releasing 2.48 ± 0.11 × 10 ⁸ t CO ₂ in the YRB from 1990 to 2020. Striking spatial disparities emerged in different regions: the upper reaches exhibited a SOC decomposition ratio of 49.66 ± 4.40%, in sharp contrast to 22.96 ± 10.35% in the middle reaches. The five provinces with the highest carbon emission rate from 1990 to 2020 were Shanxi (15.45 t CO ₂ /km ² ), Shaanxi (14.23 t CO ₂ /km ² ), Shandong (13.10 t CO ₂ /km ² ), Qinghai (11.98 t CO ₂ /km ² ), and Gansu (11.25 t CO ₂ /km ² ). Conclusion: These findings underscore the necessity of incorporating erosion-driven carbon flux dynamics into terrestrial carbon accounting frameworks, particularly in basins undergoing intensive anthropogenic modification.