The impact of short‐term flooding on soil microbial communities, soil nitrogen and maize productivity in clay loam soils of Ohio, United States

Abstract Short‐term flooding from extreme rainfall is becoming more frequent, with implications for aboveground and belowground agroecosystem function. However, few studies have explored how flooding affects the soil microbiome and plant growth in agroecosystems. We investigated how a four‐day flood influenced soil microbial communities (bacteria, archaea and fungi), soil nitrogen and maize ( Zea mays L.) productivity in a split‐plot randomized complete block design field trial in Custar, Ohio. The irrigation‐induced flood treatment was the main factor (flood, control) and fertilizer treatment was the subplot factor (220 kg N ha −1 urea, unfertilized). Soil samples were collected immediately before flooding (when maize was in the V4 growth stage) and 3, 8 and 93 days after the flood treatment ended. Soil microbial community structure was not impacted by the flood or fertilizer treatments in contrast to soil N and maize biomass at the R6 growth stage. Averaged across fertilizer treatments 8 days after flooding, autoclaved citrate extractable (ACE) protein, a measure of organically bound soil N, was lower in the flood treatment compared to the control. Soil fungal community structure correlated with soil moisture, nitrate and ACE protein in vector analyses, whereas bacterial and archaeal community structure was not correlated with these soil properties. More fungal and bacterial taxa were differentially abundant in the flood treatment than the control when comparing communities before flooding to each subsequent timepoint. Taken together, short‐term flooding increased soil bacterial and fungal variability and also reduced N availability. This work advances understanding of agroecological responses to flooding in field conditions.