3.4 AM fungi and soil properties
Fungicide (benomyl) addition significantly reduced mycorrhizal root colonisation across all plots from 2019 to 2020 (Fig. 4). Furthermore, P input alone significantly reduced mycorrhizal root colonisation in comparison with the control over two years (Fig. 5). Besides, we found that fungicide (benomyl) addition had minimal influence on soil available P and inorganic N in either 2019 or 2020 in our study (Fig. S2; all p > 0.05). In 2020, N input alone enhanced soil inorganic N by 121.17% compared with control plots (Fig. S3a and b; F 1, 28 = 93.44,p < 0.01). Moreover, P input alone enhanced soil available P in the soil by over 10 times (2019) and 14 times (2020) relative to control plots (Fig. S3c and d; F 1, 28= 81.26, p < 0.01, F 1, 40 = 191.68, p < 0.01, respectively). Mycorrhizal suppression and P input alone greatly decreased AM fungal neutral lipid fatty acid concentrations in 2019 and 2020 (Fig. S4a and b, Table S4) but did not change those of other microbial groups (Table S4, allp > 0.05).