Aggregate stability is a key factor in the evaluation of soil structure and erosion resistance, which is largely influenced by soil electric field and particle interaction. However, there are few studies on how different organic and inorganic soil conditioners change the surface electric field and interaction force of reclaimed soil to improve the aggregate stability. Therefore, a five-year field experiment was conducted to quantitatively study the effects of FeSO₄ (TM), organic fertilizer (TO), fly ash (TF), maturing agent + organic fertilizer (TMO) and fly ash + organic fertilizer (TFO), compared with control (CK) treatment, on the reclaimed soil internal force and the aggregate crushing strength. The results showed that the reclaimed soil surface potential and electric field intensity increased after 5 years of application of organic and inorganic soil conditioners. Under the same electrolyte concentration and electric field conditions, the crushing strength of aggregates (<5 μm) treated with TFO, TMO, TO, TF and TM decreased by 43.70%, 35.51%, 25.97%, 8.28% and 5.49%, respectively, compared with the control treatment, and the combination of organic and inorganic treatment (TFO and TMO) had a better effect on improving the aggregate crushing resistance. With the application of soil conditioners, the reclaimed soil DLVO force and net resultant force gradually decreased, and the order of magnitude was TFO < TMO < TO < TF < TM < CK, indicating that the application of organic and inorganic soil conditioners enhanced the van der Waals attractive force and net attractive force between reclaimed soil particles, and reduced the net repulsive force between particles. The theoretical calculation results of the reclaimed soil internal force well explain the experimental results of aggregate stability against crushing, and the relationship between aggregate crushing strength and net resultant force is exponential (p < 0.01). Generally speaking, the soil conditioners increase the net attractive force between particles, reduce the possibility of violent crushing of aggregates due to the increase of electric field intensity and improve the aggregate structural stability, among which the combined application of organic and inorganic soil conditioners has a better improvement effect. The results of this study will lay a theoretical foundation for clarifying the improvement of different soil conditioners on the reclaimed soil structural stability and erosion resistance.

Compounding Pisha sandstone (PSS) with sandy soil in Mu Us Sandy Land is a viable agronomical measure to effectively reduce soil erosion and improve soil quality due to the complementary characters and structures of the two materials. Aggregate stability is an important indicator to assess sandy soil erosion resistance and quality, which could be largely affected by soil surface electrochemical properties and particle interaction forces. However, the effect of the compound ratio and particle interaction forces on the aggregate stability of compound soils with Pisha sandstone and sandy soil is still unclear. Therefore, in this study, the electrochemical properties, particle interaction forces, and their effects on the aggregate stability of PSS and sandy soil at five volume ratios (0:1, 1:5, 1:2, 1:1, and 1:0) were determined to clarify the internal force mechanism of PSS to increase sandy soil structural stability in a 10-year field experiment. Experiments were measured by a combined method for the determination of surface properties and aggregate water stability. A ten-year field study revealed that the incorporation of Pisha sandstone significantly enhanced the soil organic carbon (SOC) and cation exchange capacity (CEC) (p < 0.05), while the CEC value notably increased from 4.68 to 13.76 cmol·kg⁻¹ (p < 0.05). The soil surface potential (absolute value) and the electric field intensity gradually decreased with the increase in the Pisha sandstone content. For the compound soil particle interaction force, the addition of Pisha sandstone enhanced the van der Waals attraction force, reduced the net repulsive force between compound soil particles, and promoted the agglomeration of aeolian sandy soil. The overall trend of the aggregate breaking strength of compound soils under different addition ratios of PSS was 1:0 > 1:1 > 0:1 > 1:5 > 1:2. When the Pisha sandstone content in the compound soils was <50%, the aggregate stability was mainly influenced by compound soil particle interaction forces, and the interaction force increase was the key reason for the aggregate breakdown. When the Pisha sandstone content in the compound soils was ≥50%, the aggregate stability was affected by the combined effects of the compound soil particle composition and particle interaction forces. These results indicate that PSS addition ratios and particle interaction force are important factors affecting the structural stability of compound soils, in which the volume ratio of PSS to sandy soil of 1:2 is the appropriate ratio. Our study provides some theoretical references for further understanding of the compound soil structure improvement and sandy soil erosion control in Mu Us Sandy Land.

With the continuous expansion of petroleum exploitation, a large amount of petroleum hydrocarbons has leaked into the Earth’s soil, which seriously threatens ecological health. Hence, a series of experiments were conducted to evaluate the performance of natural attenuation (NA), rice husk (RH), and biochar derived from rice husk (RHBC) in enhancing the bioremediation of petroleum-contaminated soil. When the biodegradation time reached 100 d, the total petroleum hydrocarbons (TPHs) biodegradation amounts of NA, RH, and RHBC were 3688.2, 4557.9, and 5913.3 mg/kg, which was equal to the biodegradation efficiency of 32.8, 40.6, and 52.6%, respectively. Compared with NA and RH, the biodegradation efficiency of n-alkanes C₁₁–C₁₅ (C₁₁ represents n-alkanes with 11 carbons, namely n-Hendecane) C₁₆–C₂₉, and C₃₀–C₄₀ in RHBC increased to 69.7~82.5%, 42.4~81.5%, and 30.2~48.1%, equivalent to 12.2~34.5%, 6.9~31.2%, and 13.5~37.1% more than NA and RH, respectively. Moreover, the half-life of biodegradation in RHBC was shorted to 83.3 d, equal to 49.7 and 67.9% of NA and RH, respectively. Furthermore, the application of RHBC could improve the dehydrogenase activity in soil and promote the growth and reproduction of petroleum-degrading bacteria (PDB), which enhances the biodegradation of petroleum hydrocarbons. This study exhibited that biochar formed from biomass pyrolysis is a potential biostimulator in enhancing the remediation of petroleum-contaminated soil by indigenous bacteria.