Location: Soil Management ResearchTitle: Impact of fertilizer, corn residue, and cover crops on mycorrhizal inoculum potential and arbuscular mycorrhizal fungi associations
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/8/2017
Publication Date: N/A
Technical Abstract: Arbuscular Mycorrhizal Fungi (AMF) increase nutrient and water acquisition for mycorrhizal-susceptible plants, which may lead to higher yields. However, intensive agricultural practices such as tilling, fallow treatments, and inorganic nutrient application reduce soil AMF. The purpose of the three existing studies: 1) fertilizer rate and form, 2) inclusion of contrasting cover crops, and 3) impacts of corn residue removal was to examine the influence of agricultural practices on the prevalence of AMF associations in crop plants. Soil Mycorrhizal Inoculum Potential (MIP) was used to measure treatment effect on AMF-plant associations. For the MIP bioassay, roots from corn plants grown in soil collected under the different treatments were evaluated after 30-days for AMF colonization. Additionally, in situ AMF colonization data was assessed in the roots of field-grown plants. In the fertilizer experiment, MIP bioassay data were significantly greater in the no-fertilizer and animal manure fertilizer treatments over the half-rate recommended fertilizer and full-rate recommended fertilizer treatments. These results indicated increased nutrient availability reduced incidence of plant-AMF associations. In the cover crop experiment, no significant differences between fallow, forage radish, and annual ryegrass treatments occurred in MIP data or in situ AMF colonization of subsequently grown corn. This was unexpected because forage radish does not form AMF associations while annual ryegrass promotes AMF colonization. In the corn residue removal experiment, corn residue removal was expected to reduce AMF associations, due to anticipated negative impacts on soil health; however, there were no significant differences observed compared to the residue retention treatment. This is the first research study to use a bioassay to demonstrate that corn residue removal was not correlated with MIP. Results further indicated that bioassays were better predictors of in situ AMF colonization if they were conducted on spring soil samples rather than fall samples.