Enhancing agricultural soil fertility and improving crop yield with the sediment dredged from the treatment wetland

Climate change has intensified extreme and unpredictable weather, including prolonged spring droughts that increasingly challenge agricultural productivity. In this context, improving soil fertility represents a critical strategy for sustaining crop production. A potential alternative to conventional soil amendments is the use of sediments dredged from water bodies. This study assessed the impact of sediment dredged from an agricultural diffuse pollution control treatment wetland (TW) on soil fertility and crop yield. Over two consecutive growing seasons (2023 with spring wheat and 2024 with buckwheat), a field plot with sediment amendment was compared with digestate, NPK mineral fertilizer, and a control plot with no amendment. Amendments were applied once in the spring of 2023. The persistence of the amendment effect in the subsequent growing season was assessed. In the drought-affected 2023 season, the sediment-amended plot retained significantly more soil moisture (up to 38%; p < 0.007) and exhibited higher total carbon content (TC ∼3%; p = 0.01) compared to other plots (maximum 18% moisture and TC ∼1.7%). These improvements promoted earlier crop development, leading to greater wheat biomass (13 t/ha) and grain yield (median 8.5 t/ha), outperforming digestate (3.3 t/ha), the control (6.3 t/ha), and NPK fertilizer (7.2 t/ha). In 2024, yield differences among plots were less pronounced (0.9–1.9 t/ha). Nevertheless, the sediment plot maintained the highest buckwheat biomass of 12 t/ha, indicating a residual benefit from the initial application. These findings suggest that sediment from TW can improve soil moisture retention and organic matter content under drought conditions, contributing to enhanced crop performance and long-term soil health. • Sediment improved soil moisture retention under spring drought conditions. • Higher organic carbon content was observed in sediment-amended plots. • Sediment boosted crop biomass and yield compared to common amendments. • Increased soil carbon supported higher buckwheat biomass in the second season. • Treatment wetland sediment offers a circular solution for sustainable soil fertility.