Negative impact of alluvial sediments on physical properties of agricultural soils affected by flooding in May 2023 in Emilia Romagna Region (Northern Italy)

Purpose: Floods are considered the major threat of soil suitability loss for agricultural purposes in floodplain agroecosystems. The present work questioned (i) how does the flooding affect soil of agricultural lands? (ii) can the mixing of deposited sediments with the covered soil be considered a suitable practice to keep soil functionality? Materials and methods: The study was conducted in three croplands of Emilia–Romagna region affected by floodings in May 2023. The sampling concerned both the deposited sediments and the covered soil, then mixtures of deposited sediment and covered soil at 1:1 ratio (soil–sed) were also obtained. These samples were analysed for the main physicochemical properties, the water infiltration and the crusting index. Results and discussion: The deposited sediments had a lower amount of nitrogen (-47%), organic C (-47%) and available phosphorus (-60%), and a higher silt content (+ 17%) compared to the covered soil. The obtained soil–sed had a lower amount of such nutrients than covered soil. Further, the higher silt content in soil–sed than in covered soil does not help the accumulation of such nutrients and lowered the water infiltration. The soil–sed had a higher crusting index (+ 24%) compared to the covered soil suggesting a higher probability of soil to promote surface runoff. Conclusions: In the investigated study sites, the flooding had a marked effect on soil physical properties because of the higher silt content and the lower organic carbon content of deposited sediments compared to covered soil. To face such issues for allowing agricultural productivity, the addition of organic amendments can be suggested due their cost–effectiveness.