Synergistic effects of arbuscular mycorrhizal inoculation and phosphorus fertilization on soil microbial properties, plant physiological characteristics, in chicory–berseem clover intercropping

Abstract

Addressing climate change and the demand for sustainable food production including forge production, this study investigates the potential of intercropping chicory ( Cichorium intybus L.) and berseem clover ( Trifolium alexandrinum L.) with arbuscular mycorrhizal fungi (AMF) and phosphorus fertilizers to enhance forage yield and soil health, defined by biological activity and nutrient cycling. Field experiments were conducted using Five treatments of monoculture and different intercropping systems under five treatments: AMF inoculation, phosphorus fertilizers (75 and 150 kg triple superphosphate), and their combinations. Soil biological parameters (e.g., microbial respiration, enzyme activities), plant traits (e.g., leaf area index, chlorophyll content), and forage yield were measured, with causal relationships analyzed using statistical modeling. Intercropping systems outperformed monoculture, with AMF-intercropping treatments exhibiting the highest soil biological activity (e.g., bacteria, microbial respiration, and enzyme activities). Chemical superphosphate application reduced soil biological activity. Bayesian Structural Equation modeling (BSEM) revealed key causal relationships: leaf area index (LAI) and chlorophyll content significantly influenced chicory forage yield, while soil microbial respiration and gram-positive bacteria impacted root colonization and LAI. In berseem clover, LAI and root colonization positively affected forage yield, though rhizobium symbiosis competed with aboveground development. The highest LER (1.107) and K (1.628) were observed in the 2:1 intercropped berseem clover- chicory and MP treatment.