Long-term nitrogen fertilization reduces extraradical biomass of arbuscular mycorrhizae in a maize (Zea mays L.) cropping system

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2018-03, Vol.255, p.111-118
• Main Authors: Jeske, Elizabeth S., Tian, Hui, Hanford, Kathryn, Walters, Daniel T., Drijber, Rhae A.
• Format: Article
• Language: English
• Subjects: Acidic soils; Agricultural ecosystems; Agricultural practices; Arbuscular mycorrhizas; Biomarkers; Biomass; C16:1cis11; Corn; Crop growth; Crop rotation; Cropping systems; Crops; Energy crops; Extraradical biomass; Fatty acids; Fertilization; Host plants; Hyphae; Nitrogen; Nutrient cycles; Nutrients; Plant roots; Roots; Soil carbon; Soil chemistry; Soil pH; Soybean; Soybeans; Storage; Studies; Temporal dynamics
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2017.11.014

•AMF biomass under continuous maize declined sharply with increasing N fertilization rate.•A similar trend, but lower in magnitude, was found for maize following soybeans.•The decline in AMF biomass was not attributed to a decline in soil pH with increasing N rate.•AMF biomass was lower during soybean growth compared to maize.•High AMF biomass under low N fertilization suggests a role in maize N uptake. Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most plant roots in natural and agroecosystems. The benefit of the relationship to AMF, host plant and soil is realized through the production of extraradical hyphae important to nutrient acquisition and soil carbon (C) storage. Maize grown in rotation with soybeans is a major agroecosystem in the Midwest and northern Great Plains of the United States and its potential to sequester C is the subject of much research. The goal of this study was to determine the impact of crop rotation and N rate on the production of extraradical AMF biomass in a long-term, minimal till field in eastern Nebraska (USA) where maize had been grown continuously (M-M; current crop in bold) or in rotation with soybeans (M-S; S-M) and treated with five nitrogen (N) rates (0, 50, 100, 150 and 300kgNha−1) for 12 years. The amount of extraradical AMF biomass was measured in the top 20cm of soil using fatty acid methyl ester (FAME) analysis of the AMF biomarker C16:1cis11. AMF biomass was highest under M-M with significant rotation by date by N rate interactions. At peak crop biomass in August the AMF biomarker under 0N addition declined from 37.5nmolg−1 in M-M to 16.7nmolg−1 in M-S to 8.0nmolg−1 in soybean following maize (S-M). In M-M extraradical AMF biomass declined sharply as N rate increased from 0 to 100kgha−1. A similar trend was found for M-S, but significant only at p