Zhaoxin Zhang

Soil cadmium (Cd) pollution threatens agricultural sustainability and food security, necessitating eco-friendly remediation strategies. This study evaluated the efficacy of intercropping annual ryegrass with maize for the remediation of Cd-contaminated soil in a 120-day experiment with triplicate pots per treatment. Three treatments were applied: maize monoculture without Cd (CK), maize monoculture with Cd (1.8 mg/kg, C1), and ryegrass-maize intercropping (1:2 row ratio) with Cd (C2). Results showed that intercropping significantly reduced soil Cd content by 70%, surpassing monoculture maize (49.4%). Maize grain Cd levels decreased to 0.07±0.01 mg/kg, with a 39% lower bioconcentration factor (BCF) in C2 vs. C1. Ryegrass demonstrated a high cadmium translocation efficiency (translocation factor, TF: 0.6-0.8), effectively reducing Cd bioavailability in the rhizosphere. Intercropping maintained soil pH at 8.60 but decreased soil organic matter (SOM) by 19.5% and available phosphorus while increasing total potassium. Soil microbial communities showed increased Actinobacteriota abundance, though Cd stress reduced overall diversity. Enzyme activities (e.g., alkaline protease and urease) increased, indicating enhanced nitrogen cycling. Statistical analyses (SPSS 26.0; ANOVA, LSD tests, p<0.05) confirmed treatment effects. While nutrient competition requires management (e.g., tailored fertilization), ryegrass-maize intercropping balances Cd remediation, crop safety, and soil functionality, offering a practical framework for sustainable farmland management.

With the advancement of agricultural modernization and the wide application of mulch film in crop planting, the problem of microplastic pollution has gradually become prominent. As an important vegetable production base in Guanzhong Plain area, microplastic pollution in vegetable fields may pose a potential threat to soil ecological environment, vegetable quality and safety and human health. This paper focuses on the current situation of microplastic pollution in vegetable fields in Guanzhong Plain, analyzes the key factors affecting the accumulation and migration of microplastics in soil of vegetable fields, and puts forward targeted prevention and control measures, aiming to provide theoretical basis and practical guidance for protecting the ecological environment of vegetable fields in Guanzhong Plain and ensuring the safe production of vegetables.

This paper utilized field monitoring, model simulation, and theoretical analysis methods to study the agricultural non-point source pollution monitoring and load quantification under the construction of high-standard farmland, focusing on the demonstration project (Fengxiang area) implemented by the group. The calculated nitrogen and phosphorus loss coefficients for the high-standard farmland in the Fengxiang area were lower. The construction of high-standard farmland effectively controlled the loss of nutrients such as nitrogen and phosphorus. The agricultural non-point source pollution load for the Fengxiang area during a normal water year was determined to be 422.688 t (TN) and 447.576 t (TP). The research results can significantly reduce the cost of water pollution control caused by agricultural non-point source pollution, enhance the utilization of land resources, greatly mitigate the direct and indirect economic losses due to agricultural non-point source pollution, and provide valuable insights for sustainable agricultural development and ecological environment protection.

Rain gardens play a key role in urban non-point source pollution control. The drainage type affects the infiltration processes of runoff pollutants. The soil properties and microbial community structures were studied to reveal the stability of the ecosystem in rain gardens with different drainage types under long-term operation. The results showed that the soil water content and total organic carbon in the drained rain gardens were always higher than that of the infiltrated ones. With the increase in running time, the contents of heavy metals in rain gardens showed significant accumulation phenomena, especially the contents of Zn and Pb in drained rain gardens were higher than that in infiltrated ones. The accumulation of pollutants resulted in lower microbial diversity in drained rain gardens than in infiltrated rain gardens, but the microbial community structures were the same in all rain gardens. The effects of drainage type on microbial community evolution were not significant, only the accumulation of heavy metals led to changes in the abundance of dominant microorganisms. There were differences in the soil environment of rain gardens with different drainage types. The long-term operation of rain gardens led to fluctuations in the soil ecosystem, while the internal micro-ecosystems of the drained rain gardens were in unstable states.

Soil surface electrochemical properties, such as specific surface area and surface charge number, are important indexes to evaluate the agricultural soil quality change. However, there is not enough focus on the effect of different improved materials on the reclaimed soil surface electrochemical characteristics. Therefore, we selected maturing agent (TM), fly ash (TF), organic fertilizer (TO), maturing agent + organic fertilizer (TMO), fly ash + organic fertilizer (TFO), and no modified material (CK) treatment for 5 years of field location experiments to study the effects of different improved materials on the surface electrochemical properties of reclaimed soil from abandoned homestead. The results showed that, compared with CK treatment, the specific surface area, surface charge number, and surface charge density of reclaimed soil increased to 11.36–14.05 m² g⁻¹, 13.49–18.58 cmol kg⁻¹, and 1.14–1.76 C m⁻² after five years of application of different improved materials, respectively, and the number of surface charge under TFO, TMO, and TO treatment increased by 28.9%, 25.2%, and 37.7% compared with CK, respectively. Meanwhile, the specific surface area increased significantly (p < 0.05), showing an order of TFO > TMO > TO > TF > TM > CK. The surface electric field strength can reach the order of 10⁸ V m⁻¹. The statistical analysis results suggest that the contents of soil organic matter (SOM), silt, and clay were positively correlated with the soil surface electrochemical properties, which were the main factors for the changes of reclaimed soil surface electrochemical properties. Our research conclusion shows that in the process of reclamation of abandoned homestead in Loess Plateau, the application of different materials is helpful to improve the soil surface electrochemical properties, among which the organic–inorganic TFO treatment was a suitable improved material treatment for improving the surface electrochemical properties and fertility of reclaimed soil.

Heavy metal pollution in soils is an issue of global concern, and many scholars have focused on Cadmium (Cd) because of its strong biological migration and toxicity. This study explored arable land soil, changes in external Cd contamination processes and its response to soil moisture conditions, and indoor simulation. After adding an external source of 5 mg/kg d.w., the distribution of soil Cd fractions content, EXC-Cd, CAB-Cd, FMO-Cd, OM-Cd, and RES-Cd, were continuously monitored under different water management regimes, and correlation analysis and regression equations were calculated. The results show that after external Cd entered arable land soils, the binging strength of pollutants and soil gradually increased with incubation time, and the distribution of Cd chemical forms was more stable under different water management regimes. The oversaturated water content promotes the transformation of EXC-Cd to other forms. The transformation of CAB-Cd fractions can be accelerated to other fractions by field capacity, and the active conversion period was 30–60 d. Not all Cd fractions correlated between each other, under the four water management regimes, but it seems that the reducibility of the soil environment was more conducive to external Cd fixation and stability. The response surface design method (RSM) was used to establish quantitative regimes between Cd fractions with incubation time and soil moisture, and the soil moisture content and incubation time had an obvious effect on FMO-Cd content, with R² = 0.9542.