The influence of a soil amendment upon the abundance and interaction of arbuscular mycorrhizal fungi with arable soils and host winter wheat

Arbuscular mycorrhizal (AM) fungi form close symbiotic relationships with an estimated 70% of terrestrial plant species and aid in the acquisition of soil nutrients. Due to their symbiotic relationship, AM fungi are able to provide a host with acquired soil bound nutrients in exchange for host produced photosynthetic carbohydrates. AM fungal-host relationships are affected by land and soil management practices employed in arable farming. Tillage, for example, can be one of the most detrimental physical disturbances to AM fungal populations. The present study aims to utilise compost and a commercially available AM fungal inoculant to amend arable soils supporting Zulu winter wheat, under controlled conditions, to determine changes in the degree of AM fungal-host symbiosis, crop growth and development, as well as comment on the potential integration of these soil amendments into arable soil management practices. Soils were sampled from 3 field from each of the 3 participating farms practicing either conventional, reduced, or zero tillage. Soil textures were assessed for each sampled soil. Via the employment of AM fungal symbiosis quantification methods, and proxy parameters for fungal biomass, AM fungi were able to be compared between soil amendments and their effects on crop growth and development. The current study was able to show soils amended with multipurpose compost produced a greater degree of AM fungal-host associations for all soil types across all tillage practices. Compost amended soils were also able to show increases in crop tiller numbers and their respective crop height. Reduced wheat root length was also seen from compost amended soils, however, this was correlated to an increase in AM fungal root arbuscules. Commercial AM fungal inocula, on the other hand, was seen to reduce AM fungal associations with their host as well as have little to no influence on crop root length and crop height. Number of tillers per plant were, however, seen to marginally increase with the addition of a commercial AM fungal inocula. From results presented in the current study, conclusions can be drawn towards the advantageous addition of multipurpose compost to arable soils for the tillage and soil types studied. Furthermore, the addition of compost is a more cost effective change to soil management.