Water management effect on soil oxidation, greenhouse gas emissions, and nitrogen leaching in drained peat soils

Abstract

AbstractSoil subsidence of peatlands occurs worldwide due to drainage. The Everglades Agricultural Area (EAA), located in South Florida, has been drained for agriculture since 1914, with subsidence resulting in shallow soils in certain areas. The purpose of this study is to determine the impact of water management strategies on soil oxidation and N release as affected by differences in proximity to the bedrock. Oxidation rates (CO2 efflux), as well as CH4 and N2O emissions, were measured in lysimeters filled with shallow and deep peat subjected to four water treatments. Additionally, NO3–N, NH4–N, soluble organic N, and dissolved organic C were measured in leachate obtained from the collected soils. Average annual emissions from constantly drained soils were 298 g CO2–C m–2 yr–1, with most of the oxidation taking place between June and October. Short flood cycles increased annual oxidation rates compared with constantly drained soils, which had the second highest oxidation rate. Constantly flooded soils had the lowest annual oxidation rates, followed by summer flooded soils. Total N lost in leachate was highest for constantly drained soils, with NO3 being the dominant form. The deep soils had higher losses of soluble N and C, whereas NO3 losses from shallow soils were higher. Soil oxidation rates did not differ depending on proximity to the bedrock. We conclude that strategies that avoid short flooding cycles and include crop rotations that allow flooding during summer can reduce oxidation and N losses in leachate from EAA peats.