Due to soils from arid regions with high lime and low organic matter content, farmers receive low yields along with high costs of agricultural inputs, which causes them to look for a solution. In this context, Arbuscular mycorrhizal fungi (AMF) have great potential to reduce fertilizer use by mediating soil nutrient cycles. However, little is known about studies of AMF inoculum on microbial biomass carbon (C), nitrogen (N), and phosphorus (P) cycling during vetch plant vegetation in calcareous areas. In this study, changes in soil biogeochemical properties related to soil C, N, and P cycling were investigated with five different AMF inoculations under vetch (common Vetch (CV; Vicia sativa L.) and Narbonne Vetch (NV; Vicia narbonensis L.) growing conditions. For the field study, a total of five different mycorrhizae were used in the experiment with the random plots design. AMF inoculation decreased the lime content of the soil, and the highest decrease was observed in NV with Glomus (G.) intraradices + G. constrictum + G. microcarpum inoculation (24.41 %). The highest MBC content was recorded in CV vetch G. intraradices (1176.3 mg C kg^-1) and the highest MBN content in NV vetch G. intraradices + G. constrictum + G. microcarpum (1356.9 mg C kg^-1). CAT activity of soils was highest in CV vetch G. intraradices (31.43 %) and lowest in NV vetch G. intraradices + G. constrictum + G. microcarpum (72.88 %), urease enzyme activity decreased in all treatments except G. constrictum + Gigaspora sp. and G. mosseae inoculations in CV. The highest DHG activity was detected in GF (15.72 %) AMFs in CV and GI (21.99 %) in NV. APA activity was highest in Glomus constrictum + Gigaspora sp. (23.33 %) in CV and Glomus fasciculatum (10.08 %) in NV. In CV plots, G. intraradices + G. constrictum + G. microcarpum (91.67 %) isolates had the highest and G. intraradices community had the lowest RC% (97.33 %) in mixed mycorrhiza species, while in NV plots G. fasciculatum inoculum had the highest and G. intraradices community had the lowest RC%. This study has important implications for the application of AMF for sustainable agriculture. When the results of the study were evaluated, the most effective AMF isolates in terms of C, N, and P cycles were G. constrictum + G. fasciculatum + Gigaspora sp. in Common vetch variety, and G. intraradices in Narbonne vetch variety.

This study was carried out to examine the interaction of enzyme activities, microbial biomass carbon, and CO₂ respiration with heavy metals under different land uses in terms of quality and sustainability of the soil. There is a statistically significant positive correlation between dehydrogenase enzyme activity and Mn, Pb, Cd, and Co, while it was negative between Cr. There was a positive correlation between catalase enzyme activity and Mn and Pb and between urease and Co. The higher interaction of dehydrogenase activity with heavy metals, which is included in the endo enzyme group, has been explained as a much stronger effect of heavy metals on living microorganisms and endoenzymes than extracellular enzymes stabilized on clay minerals and organic matter. The high clay content of the soil is thought to reduce some of the negative effects of heavy metals on enzymes. The results of this study may be good indicators of enzyme activities, especially dehydrogenase, catalase, and urease, for soil health and quality, chemical degradation and restoration processes, and ecosystem functioning in soils contaminated or to be contaminated with heavy metals. It shows that the activities of these enzymes are very sensitive and can decrease rapidly in case of high concentrations of heavy metals.

This study aims to investigate the effects of the combined treatment of biochar (BC) and arbuscular mycorrhizal fungi (AMF) on cotton plants, focusing on morphological and physiological characteristics, nutrient content, and soil enzyme activities. The study examined the effects of different biochar doses in mycorrhiza-inoculated (M +) and non-inoculated (M −) treatments (0% BC + 200 kg N ha⁻¹, 1.5% BC + 200 kg N ha⁻¹, 3% BC + 200 kg N ha⁻¹). The results showed that the highest SPAD value (34.66%) was observed in the M( +) + 3.0% BC treatments. NDVI values increased by 25.29% in M( +) + 3.0% BC treatments. M( +) treatment increased the N, NO₃ ⁻, and soil enzyme activity was higher in the M( +) treatment. However, enzyme activity decreased as BC dose increased in both M( +) and M( −) treatments, with the most significant decrease observed in the 3.0% BC treatments. Nitrate reductase enzyme activity (NRA) decreased in all treatments except the 3.0% biochar treatment. M( +) treatment increased soil urease content by 27.24% compared to the M( −) treatment. Additionally, plant height, root length, nodule count, and spore number increased with increasing biochar doses, with the highest increase observed in the M( +) + 3.0% BC treatments. Positive correlations were found between SPAD, NDVI, and nutrients such as Fe, Cu, Mn, and root attributes. Negative correlations were observed with Mg and CAT enzyme activity. Urease, DHG, and CAT enzyme activities decreased significantly with increasing BC doses, particularly in M( +) treatments. Biochar and AMF co-treatment enhanced growth, root parameters, spore count, NDVI, SPAD, and soil and plant enzyme activities in cotton plants. The combined treatment of biochar and AMF is beneficial for cotton production. The findings of this research have significant potential implications for sustainable cotton production and soil management practices, particularly in optimizing mycorrhiza and biochar to enhance soil fertility, improve water retention, and reduce the need for chemical fertilizers.