Title: Cover crop mixtures for promoting arbuscular mycorrhizal fungi in production agriculture Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 29, 2011
Publication Date: May 24, 2011
Citation: Taheri, W.I., Lehman, R.M., Osborne, S.L. 2011. Cover crop mixtures for promoting arbuscular mycorrhizal fungi in production agriculture. Soil Ecology Society, Kelowna, British Columbia, Canada. Technical Abstract: Arbuscular mycorrhizal fungi (AMF) associate with an estimated 80-90 percent of flowering plants and virtually every crop species that supplies food to the world. AMF play a vital role in nutrient uptake and are particularly adept at increasing phosphorus availability to plants. With the growing emphasis on sustainability, these organisms have recently attracted attention as both biocontrol agents, and as a potential substitute for phosphorus fertilizer. Recent research has demonstrated that conventional agricultural practices have caused a decline in AMF populations compared to natural ecosystems. We found that a native prairie remnant had over 200 times the number of spores than local agricultural fields had in total propagules. Field and landscape levels of inoculation with these organisms are currently prohibitively expensive, so we investigated the manipulation of cover crops as a means of increasing AMF propagules in agricultural soils, examining both quantity and diversity. Utilizing a full factorial experiment we tested oats, vetch, canola and fallow treatments. Mixed cover crops resulted in the highest percent colonization in the roots of the subsequent corn crop. Vetch as a cover crop produced the lowest subsequent colonization of corn roots, performing significantly poorer than no cover crop. The number of soil AMF propagules also responded to positively to the mixture (oats-vetch-canola) of cover crops in this set of plots and to an oats-pea mixture used in a second set of replicated plots established on a producer’s farm located within a differing soil-climatic regime. At another producers’ farm, we are assessing numbers of AMF propagules and spores in soil samples collected from paired locations plus or minus a five-way cover crop mixture (winter wheat-clover-vetch-turnip-radish) that was seeded following spring wheat harvest. Cover crop mixtures may simultaneously reduce seasonal fallow and provide plant diversity that promote higher numbers and diversity of AMF to deliver benefits to cash crops like corn in the upper Midwest.