Arbuscular mycorrhizal (AM) fungi establish mutualistic symbioses with plant roots, enhancing plant growth and improving soil fertility through nutrient exchange. Among these, soil nitrogen (N) and phosphorus (P) are critical for symbiosis formation, directly influencing nutrient uptake and translocation within the symbiotic system. This study aimed to examine the regulatory roles of N and P levels on AM fungal development and associated bacterial communities in culture. Sorghum was used as the host plant in pot experiments with two AM fungi, Rhizophagus irregularis and Funneliformis mosseae, under varying N and P concentrations. The analyzed parameters included mycorrhizal colonization, propagule production, plant biomass, nutrient contents (N, P, and K), and bacterial community diversity. N3P1 treatment (150 mg/L N, 30 mg/L P) yielded the highest colonization rate, spore production, and arbuscule abundance in both AM fungal symbionts. At equivalent N and P concentrations, the N, P, and K contents in inoculated plants were significantly higher than those in controls. AM fungal inoculation markedly increased the bacterial diversity in the culture (Shannon index raised by 15.2–28.7%) and enriched beneficial taxa, such as Bradyrhizobium and Pseudomonas. N and P concentrations substantially influenced AM fungal symbiosis, with optimal development observed under N3P1 conditions. By regulating AM symbiotic establishment, N and P levels reshaped microbial community composition, providing theoretical guidance for industrialized AM fungal cultivation and inoculant production.

Aqueous ammonia can release high nitrogen inorganic substances of ammonia and has been used as soil fumigant. However, the information about how fumigation with ammonia affects the soil microbial community is still limited. In this study, a laboratory microcosm experiment was conducted to evaluated the effectiveness of ammonia fumigation in controlling root-knot nematodes (RKNs), its influence on soil microbial diversity, and its impact on nitrous oxide (N ₂ O) emissions. The results indicated that Ammonia treatment increased N ₂ O emissions and decreased the RKNs population by 75.73%. Adding the inhibitors N-(N-butyl) thiophosphoric triamide (NBPT) and Dicyandiamide (DCD) to aqueous ammonia can mitigate N ₂ O emissions. Compared with CK treatment, Soil enzyme activities, including those of urease, nitrate reductase, and nitrite reductase, were enhanced in each treatment. The fungal Sobs index was significantly higher in CK treatment than in the other treatments, whereas bacterial alpha diversity remained unaffected. This study also indicates that soil fumigation with aqueous ammonia has the potential to regulate fungal communities and important key reactions involved in nitrogen cycling.