Cultivating soil life: a diluted compost extract solution stimulated arbuscular mycorrhizal symbiosis in MYRCIANTHES CISPLATENSIS seedlings

Inspired by the living soil theoretical framework and agroecological principles, we designed an experiment to study the effect of compost extract on arbuscular mycorrhizal symbiosis (AMS) with the argentinean native tree Myrcianthes cisplatensis. AMS is a symbiotic relation between arbuscular mycorrhizal fungi (AMF) and 70% of terrestrial plants that evolved since plants began to live in terrestrial ecosystems. As the source of AMF a soil enriched with indigenous AMF populations associated with M. cisplatensis in situ was made. We found that a 1:500,000 dilution of the compost extract stimulated AMS independently of the presence of microorganisms in the extract, strongly suggesting that the stimulation was due to the presence of soluble biomolecules synthesized by the metabolism of the compost. Our results contribute to the generation of knowledge regarding the underlying mechanisms of biological amendments, in this case a compost extract, on the stimulation of AMS with native tree seedlings.