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Dynamics of Measured and Simulated Dissolved Phosphorus in Runoff from Winter‐Applied Dairy Manure
Author(s) -
Vadas Peter A.,
Stock Melanie N.,
Arriaga Francisco J.,
Good Laura W.,
Karthikeyan K. G.,
Zopp Zachariah P.
Publication year - 2019
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2018.11.0416
Subject(s) - surface runoff , snowmelt , manure , environmental science , liquid manure , soil water , hydrology (agriculture) , tillage , surface water , agronomy , soil science , environmental engineering , geology , ecology , geotechnical engineering , biology
Agricultural P loss from fields is an issue due to water quality degradation. Better information is needed on the P loss in runoff from dairy manure applied in winter and the ability to reliably simulate P loss by computer models. We monitored P in runoff during two winters from chisel‐tilled and no‐till field plots that had liquid dairy manure applied in December or January. Runoff total P was dominated by nondissolved forms when soils were bare and unfrozen. Runoff from snow‐covered, frozen soils had much less sediment and sediment‐related P, and much more dissolved P. Transport of manure solids was greatest when manure was applied on top of snow and runoff shortly after application was caused by snowmelt. Dissolved P concentrations in runoff were greater when manure was applied on top of snow because manure liquid remained in the snowpack and allowed more P to be available for loss. Dissolved runoff P also increased as the amount of rain or snowmelt that became runoff (runoff ratio) increased. The SurPhos manure P runoff model reliably simulated these processes to provide realistic predictions of dissolved P in runoff from surface manure. Overall, for liquid dairy manure applied in winter, dissolved P concentrations in runoff can be decreased if manure is applied onto bare, unfrozen soil, or if runoff ratio can be reduced, perhaps through greater soil surface roughness from fall tillage. Both management approaches will allow more manure P to infiltrate into soil and less move in runoff. SurPhos is a tool that can reliably evaluate P loss for different management and policy scenarios for winter manure application. Core Ideas Better information is needed on winter P loss in runoff from winter‐applied manure. Winter runoff after manure application is dominated by dissolved P. Event hydrology exerts a strong control on runoff dissolved P concentrations after manure. The SurPhos model can reliably estimate dissolved P loss in runoff for winter manure application.