Understanding how extended excess soil moisture exacerbated by extreme weather events affects changes in iron (Fe) chemistry is crucial for assessing environmental risk associated with soil phosphorus (P) in high P soils. The objective of our study was to assess the effects of three soil moisture regimes (field capacity, water saturation, and waterlogging), two Fe3+ nitrate level (Fe3+ nitrate addition and no Fe3+ nitrate addition), and the duration of incubation (0, 3, 7, 14, 21, 28, 35, 49, 63, 90, and 120 days) on the (i) reduction of ferric (Fe3+) to ferrous (Fe2+) iron, (ii) solubility of soil P, and (iii) soil microbial biomass and greenhouse gas emissions. Surface soils (0–20 cm) were collected from a maize silage field located in the Fraser Valley (British Columbia, Canada). Decreased redox potential (Eh) of 155 mV in waterlogged soils coincided with the reduction of Fe3+ to Fe2+ of about 1190 mg kg−1 and an increase in soil pH of 0.8 unit compared to field capacity regime at 120 days after pre-incubation (P