|Alverson, Nickolas - University Of Massachusetts|
|Jeranyama, Peter - University Of Massachusetts|
|Demoranville, Carolyn - University Of Massachusetts|
Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2017
Publication Date: 1/10/2018
Citation: Kennedy, C.D., Alverson, N., Jeranyama, P., Demoranville, C. 2018. Seasonal dynamics of water and nutrient fluxes is an agricultural peatland. Hydrological Processes. https://doi.org/10.1002/hyp.11436.
DOI: https://doi.org/10.1002/hyp.11436 Interpretive Summary: Identifying seasonal components of nutrient runoff will help focus remedial management strategies to improve water quality. A team of researchers from ARS and the University of Massachusetts conducted a 2-yr study to evaluate seasonal export of nitrogen (N) and phosphorus (P) runoff from a cranberry peat bog in Massachusetts. Results show elevated N and P export in the spring and summer seasons, contrasting with previous work linking elevated N and P export to the autumn cranberry harvest. Given the timing of discharges, the authors propose remedial strategies along the lines of channel restoration, which may enhance retention of highly reactive forms of N in summer discharge.
Technical Abstract: The American cranberry (Vaccinium macrocarpon Ait.) is an important part of the cultural heritage and economy of southeastern Massachusetts, yet water quality concerns, wetland protection laws, and increased competition challenge its production. Despite their regional importance, few data on nitrogen (N) and phosphorus (P) export from cranberry peatlands exist. Here we report water and nutrient budgets for a 2.12-ha cranberry bed over a 2-yr period from 2013-2015. Daily to weekly measurements of water and nutrient fluxes were used to evaluate seasonal differences in the net export of N and P from the cranberry bed. Net N export ranged from 9.3-16.3 kg N ha-1 yr-1, consisting of 72% ammonium and 28% total (dissolved + particulate) organic N. Net P export ranged from 1.5-3.3 kg P ha-1 yr-1, and was predominantly (>97%) composed of particulate P. Although autumn and winter floods have been identified as periods of relatively high nutrient runoff from cranberry agriculture, in this study, annual variation was related to differences in spring and summer nutrient export. Seasonal factors that may contribute to elevated spring and summer nutrient export include mineralization of peat N, breakdown of soil aggregates, fertilizer application timing, and rainfall intensity. In the late spring, sharp increases in N export were consistent with temperature-mediated release of N from peat soils. However, fertilizer application 1 d prior to a very large summer storm (i.e., 5th largest in 88 years) was tied to 15% and 11% of the annual N and P export, respectively, in that year. Although an extreme case, the storm event clearly illustrates the environmental significance of fertilizer timing in cranberry production. In-situ management of surface water discharges may not always be feasible in the summer, as the cranberry plant is particularly sensitive to periods of flooding at bloom. However, absent significant rain events, the relatively low surface discharge rates, at least compared to flood releases, may be amenable to remedial strategies, such as channel restoration, that enhance retention of reactive ammonium.