Arbuscular Mycorrhizal Fungus Spore Populations Respond to Conversions between Low‐Input and Conventional Management Practices in a Corn‐Soybean Rotation

Abstract

AbstractArbuscular mycorrhizal fungi (AMF), ubiquitous symbiotic fungi colonizing plant roots, can contribute to plant growth by improving nutrient uptake and stress tolerance. The influence of management practices and crop species on AMF spore populations and percent root colonization was examined during conversion from conventional to low‐input and low‐input to conventional management systems in 2‐yr crop rotations planted to alternating corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] sequences established in two adjacent areas with different management histories. During the previous 25 yr, the low‐input area had received no fertilizer or herbicide inputs, while the conventionally managed area had received recommended fertilizer and herbicide inputs. No input (NI), organic input (OI), minimum input (MI), and conventional input (CI) management systems were established within each crop sequence. Weeds were the dominant vegetation in both years in the low‐input area. Average AMF spore population in this area was 292 spores g−1 soil. In the conventionally managed area, only crop plants were present during the first year, while small weed populations had developed by the end of the second year in NI and OI. Average AMF spore population in the conventionally managed area was 175 spores g−1 soil. Average AMF colonization percentage in the low‐input area was 27.5%, while in the conventionally managed area it was 24.5%. AMF colonization percentages were not correlated with AMF spore populations and did not appear to be influenced by the management systems established within each area. Management systems appeared to influence AMF spore populations by their effect on weed populations.