The use of crop polycultures can provide several benefits to agroecosystems, including supporting more diverse pollinator and microbial communities. Many plant candidates for perennial crop polycultures are derived from or closely related to perennial grassland species. Because many grassland species are highly dependent on arbuscular mycorrhizal (AM) fungi, it is likely that many perennial crops also rely on this relationship. Perennial agricultural plantings typically follow massive disturbances, such as tillage, which have more disturbed and ineffective fungal communities. Therefore, the reintroduction of AM fungal communities may benefit crop productivity. We tested the benefits of a native AM fungi as well as different plant community arrangements on the growth of three perennial crop candidates alfalfa, an oil seed crop candidate Silphium integrifolium and a wheatgrass alternative Kernza™ (intermediate wheatgrass). An old brome field was tilled and inocula was drilled in using a seed drill prior to planting the experiment with all possible monoculture, biculture, triculture planting arrangements for the three plant species. Here we present data on the first year of plant growth including fodder biomass and plant seed set for intermediate wheatgrass and alfalfa.
Results/Conclusions
During the first growing season, both plant community arrangement and the addition of a native AM fungal inocula influenced productivity. Total productivity increased around 20% with native AM fungi amendments. Both intermediate wheatgrass and alfalfa were more productive with inoculation, but this pattern was only significant for alfalfa. Plant community arrangement also had strong effects crop productivity, where monocultures were often among the least productive systems. Productivity of both intermediate wheatgrass and alfalfa was greatest when grown in biculture with Silphium integrifolium or in triculture with all plant species. We found similar patterns with Kernza™ seed production. These data demonstrate the value of using a holistic approach to the initiation of perennial polycultures that includes providing plants with beneficial microbiome components such as mycorrhizal fungi. Additionally, these data support the use of companion plants in perennial agriculture as we found that more diverse plantings provided improvements in plant productivity. Furthermore, both microbial inoculation and plant arrangement diversity improved total community productivity in single growing season for these perennial crop candidates.