Submitted to: Dickinson Research Extension Center Publications
Publication Type: Experiment Station
Publication Acceptance Date: 5/20/2011
Publication Date: 9/30/2011
Citation: Ashley, R.O., Nichols, K.A. 2011. Arbuscular mycorrhizal fungi and glomalin in fumigated and natural soils. Dickinson Research Extension Center Publications. 2011 Annual Report. www.ag.ndsu.edu/DickinsonREC/annual-reports-1/2010-annual-report/agron10i.pdf. Interpretive Summary: Arbuscular mycorrhizal fungi (AMF) vary in the strength of their relationship with host crop plants. Corn has a very strong relationship while wheat has a moderate to weak relationship. In this demonstration study, plots in wheat fields were either fumigated or not fumigated with methyl bromide prior to wheat seeding to reduce fungal pathogens common in continuous wheat systems. Wheat yield increased in fumigated plots but the following year corn planted into fumigated plots was stunted and the leaves had a purplish hue common under phosphorus stress. Rhizosphere soil samples were collected with roots separated and examined for AMF colonization and the soil extracted for glomalin. There was a significant decrease in AMF colonization in the corn roots from fumigated plots but no corresponding difference in glomalin levels. The reduced plant growth did impact final yields indicating that when using methyl bromide as a fumigant caution should be taken when choosing which crops to use in the rotation. A decline in AMF may not be measured in a crop that is not very dependent upon these fungi immediately following fumigation, but the reduced inoculum density impact subsequent crops, particularly if these crops are highly mycorrhizal.
Technical Abstract: Arbuscular mycorrhizal fungi (AMF) have strong associations with some crops such as corn (Zea mays L.) while other crops, such as wheat, have little or no association. This study was conducted to determine whether symptoms expressed by corn grown on soil fumigated 19 m prior to seeding was caused by a reduction in AMF. The effects on AMF colonization, glomalin concentration, nutrient levels in plant tissues and grain yield were investigated near New Hradec, ND on a Moreau silty clay loam soil. AMF root colonization was higher in corn roots from natural soils compared to samples from the fumigated plots while no significant difference in glomalin was detected. This demonstration study did show fumigation impacted AMF and grain yield with higher wheat yields in fumigated plots and followed by lower corn yields. However a larger study including other locations and more replications with the same treatments and tissue testing for nutrient content is needed to make conclusions applicable to the larger area.