Temporal patterns in sediment, carbon, and nutrient burial in ponds associated with changing agricultural tillage

Lakes and ponds play a disproportionate role in retaining sediment, carbon, nitrogen, and phosphorus, potentially mitigating negative environmental effects. However, how sequestration rates change over a pond’s lifetime, and how rates are affected by watershed land use practices remains poorly characterized. In this study, we quantified sediment, carbon, nitrogen, and phosphorus burial rates, and the values of these ecosystem services, in three ponds. The ponds were 19–25 years in age (as of 2019), and their watersheds experienced a shift in the early 1990s to conservation tillage. We found that sediment burial rates decreased over time within these ponds (establishment to 2006, vs. 2006 to 2019), consistent with reduced soil erosion rates associated with conservation tillage. However, patterns in carbon, nitrogen, and phosphorus burial rates were not as clear; almost half of the elemental burial rates we quantified increased over time. We suggest that this may be due to increased importance of in-pond processes, such as in situ primary production and subsequent organic matter sedimentation, as the ponds age. Finally, we estimated the ecosystem service value of sediment, carbon, and nutrient retention by these ponds. We estimate that these three ponds provided ecosystem services equal to approximately 360,083 US$ over their lifetimes through burial of sediment, carbon, nitrogen, and phosphorus. Our results show that small retention ponds can provide considerable environmental and economic value by trapping and retaining sediments and nutrients.