Exploring economic assessment of the arbuscular mycorrhizal symbiosis

The arbuscular mycorrhizal (AM) symbiosis has long been projected as one of the sustainable saviors for achieving food security for mankind. However, there exist conflicting views regarding recommending AM fungi as inocula to farmers. Fungal, host, soil and climatic factors affect AM efficacy in the field. The process of identifying, calculating and comparing the costs and benefits of AM symbioses in economic terms is of international interest from both farmer and industry perspectives. It has not yet been possible to economically quantify the benefits of AM fungi in agroecosystems. Some potential benefits such as increased yield, lower fertilizer consumption and better disease tolerance can be measured quantitatively by cost-benefit analyses, but others such as reductions in soil erosion and nutrient leaching, soil carbon sequestration, phytoremediation, renaturation and landscaping are mainly qualitative and cannot be assessed by conventional cost-benefit methodologies. We identify and explore approaches to assessing economic benefits of inoculation with AM fungi and the risks and limitations involved. To ensure that all potential benefits of AM symbioses are given due cognizance, we propose any economic evaluation should also use contingent methods as applied to economic assessment of biodiversity and afforestation. Development of a framework involving systematic measurements of factors involved in establishment and function of AM symbioses should address risks in mismeasurement and resolve issues related to incomplete knowledge and potential conflicts.