Utilizing perennial crops in agriculture systems may improve water and soil conservation, increase soil health, and reduce inputs compared to conventional agriculture. These benefits may rely on the interaction between the crop planted and communities of soil biota. Understanding how soil communities respond to long-lived crop species, the cessation of tillage, and changes in plant diversity is critical to enhance the predictability and sustainability of ecosystem benefits from perennial agriculture systems. We characterized the responses of soil fungal communities to long term differences in management at The Land Institute in Salina, Kansas. We targeted soil fungi because they contain important crop pathogens, symbiotic organisms such as mycorrhizal fungi, and saprotrophs which play a major role in nutrient cycling. Plots reflected three planting treatments: perennial monocultures of intermediate wheatgrass (which produces the grain Kernza®), conventionally tilled crop rotation of annual wheat/sorghum/soybeans, and a species diverse native prairie reconstruction. Soils were taken at two depths, and fungal communities were assessed through next-generation sequencing (Illumina Mi-seq) and assignment of taxa (OTUs) into functional groups. Our central question was whether the long-term treatments drove consistent divergence in fungal community structure, diversity, and the dominance of particular functional groups.
Results/Conclusions
Soil fungal community structure was similar between the perennial monoculture and the native vegetation planting treatments, but these communities were both distinct from the annual agriculture treatment. Fungal communities also differed with depth within each planting treatment. These overall patterns were consistent for subsets of fungi classified as saprotrophs and mutualists. Diversity indices were similar among planting treatments, but saprotroph richness was greater in annual agriculture treatments and perennial monocultures had the greatest number of symbiotrophs. Overall fungal community diversity and richness decreased with depth, and pathotroph richness decreased with depth only in the annual agriculture treatment. These results reinforce findings that tillage drives soil fungal community structure, including ecological guilds that perform important functions. Ongoing research is now testing the functional consequences of these community shifts, including separating the abiotic and biotic consequences of soil differences.