The combined implementation of intercropping systems and arbuscular mycorrhizal fungi (AMF) inoculation represents a promising phytoremediation strategy for heavy metal-contaminated farmland, providing both ecological and economic benefits.  However, additional research is necessary to understand the influence of AMF and intercropping on Cd bioavailability.  This study examines the synergistic effects of maize–soybean intercropping and AMF inoculation on crop growth, cadmium (Cd) allocation patterns, and rhizosphere soil dynamics through comprehensive field and pot experiments.  Field trials revealed significant yield advantages in maize–soybean intercropping systems, with land equivalent ratios (LERs) of 1.62 (common maize) and 1.64 (sweet maize).  Intercropping decreased soybean Cd accumulation across all tissues, notably in grains (42.8% reduction), while maintaining maize grain Cd concentrations below China’s food safety threshold (0.20 mg kg^–1).  The metal removal equivalent ratio (MRER) achieved 1.33–1.38 in field conditions, validating intercropping’s dual advantage in productivity and Cd phytoextraction.  Pot experiments indicated the AMF-inoculated intercropping system (IN+A) increased maize yield by 16.4% while reducing Cd accumulation in both crops, with grain concentrations meeting safety standards.  Rhizosphere analysis demonstrated IN+A treatment substantially improved soil health indicators: 34.5% reduction in bioavailable Cd, elevated pH, decreased redox potential (Eh), and enhanced catalase activity.  AMF colonization rates were 2.2–4.3 times higher in inoculated treatments (11.5–14.0%) vs. controls (3.2–5.3%).  These results establish that AMF-enhanced legume–cereal intercropping reduces Cd bioavailability through soil alkalinization (pH increase) coupled with redox potential reduction, and metal allocation plasticity redirecting Cd to root tissues.  This interaction between microbial symbiosis and plant community design stabilizes Cd in soils while maintaining crop safety (grain Cd<0.20 mg kg^–1), establishing an ecoengineering approach for contaminated farmland remediation.

Insight into the carbon turnover in soil aggregates and density fractions is essential for reducing the uncertainty in estimating carbon pools on the Tibetan Plateau, and how they vary with land use type is unclear.  In this study, the effect of land use type on carbon storage and fractionation was quantified based on organic carbon and its ¹³C abundance at the microscale of soil aggregates and density fractions in Tibetan alpine ecosystems.  The sequence of soil aggregate destruction in the land use types of plantation (13.1%)<shrubland (32.7%)<grassland (47.9%)<farmland (61.8%) shows that plantations strengthen the soil structure.  Plantation land had a greater contribution of light fraction organic carbon (28.3%) but a lower contribution of mineral-associated organic carbon (40.6%) to the carbon stock compared to farmland (13.5 and 70.3%).  Interestingly, plantation land enhanced the aggregational differentiation of organic carbon and ¹³C in each density fraction, whereas no such phenomenon existed in the soil organic carbon.  Carbon isotope analyses revealed that carbon transfer in the plantation land occurred from the light fraction in macroaggregates (–24.9‰) to the mineral-associated fraction in microaggregates (–19.9‰).  When compared to the other three land use types, the low transferability of carbon in aggregates and density fractions in plantation land provides a stable carbon pool for the Tibetan Plateau.  This study shows that plantations can mitigate global climate change by slowing carbon transfer and increasing carbon storage at the microscale of aggregates and density fractions in alpine regions.