Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Agriculture 157 [9 ] soil P status rhizospheric organisms bacteria nematodes mycorrhizal fungi biodiversity-function relationships 2021 fdi:010080985 ENG Agriculture ISI:000622002500001 2 10.3390/agriculture11020157 https://www.documentation.ird.fr/hor/fdi:010080985 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers21-03/010080985.pdf 11 Horizon (IRD) Plants evolve complex interactions with diverse soil mutualist organisms to enhance P mobilization from the soil. These strategies are particularly important when P is poorly available. It is still unclear how the soil P source (e.g., mineral P versus recalcitrant organic P) and its mobility in the soil (high or low) affect soil mutualist biological (ectomycorrhizal fungi, bacteria and bacterial-feeding nematodes) richness-plant P acquisition relationships. Using a set of six microcosm experiments conducted in growth chamber across contrasting P situations, we tested the hypothesis that the relationship between the increasing addition of soil mutualist organisms in the rhizosphere of the plant and plant P acquisition depends on P source and mobility. The highest correlation (R-2 = 0.70) between plant P acquisition with soil rhizosphere biological richness was found in a high P-sorbing soil amended with an organic P source. In the five other situations, the relationships became significant either in soil conditions, with or without mineral P addition, or when the P source was supplied as organic P in the absence of soil, although with a low correlation coefficient (0.09 < R-2 < 0.15). We thus encourage the systematic and careful consideration of the form and mobility of P in the experimental trials that aim to assess the role of biological complexity on plant P nutrition. 068 ; 074 UR210 Pakistan