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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #333911
Title: Seasonal manure application timing and storage effects on field and watershed level phosphorus losses

Author
item LIU, JIAN - Pennsylvania State University
item Veith, Tameria - Tamie
item COLLICK, AMY - University Of Maryland Eastern Shore (UMES)
item Kleinman, Peter
item BEEGLE, DOUG - Pennsylvania State University
item Bryant, Ray

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2017
Publication Date: 11/16/2017
Citation: Liu, J., Veith, T.L., Collick, A.S., Kleinman, P.J., Beegle, D.B., Bryant, R.B. 2017. Seasonal manure application timing and storage effects on field and watershed level phosphorus losses. Journal of Environmental Quality. 46:1403-1412. doi: 10.2134/jeq2017.04.0150.

Interpretive Summary: The trade-offs in phosphorus loss due to applying manure frequently during fall and winter, but at low rates, versus storing manure throughout the season or year and then applying at high rates in the spring and/or fall, are unclear. We simulated seasonal manure application timing and storage effects on phosphorus loss in a Pennsylvania watershed. Winter and fall applications of manure resulted in risk of larger annual phosphorus losses from fields than spring application, but phosphorus loss could be reduced by applying manure to low-slope fields, not applying near streams, increasing crop cover in fall and winter, and decreasing manure rates. Although 12-month storage across the watershed (that is, spreading all manure in the spring), reduced total yearly amounts of phosphorus lost, compared to 6-month or 3-month storage, it led to great peaks of phosphorus concentrations in the stream in spring. Results point to the need to assess trade-offs associated with change in manure storage capacities in the region.

Technical Abstract: The timing of manure application to agricultural soils remains a contentious area of nutrient management, particularly with regard to the impact of timing on nutrient loss in runoff and downstream water quality. We examined the effect of seasonal manure application timing and manure storage capacity on P losses at both field and watershed scales in a 730 ha watershed in central Pennsylvania, USA with extensive field management and monitoring of base flow water quality. Different manure management scenarios were assessed over an 11 year period with a version of the Soil and Water Assessment Tool (SWAT) that had been updated to improve the representation of variable source area hydrology and P cycling. At the field level, we found that fall and winter manure applications resulted in greater losses of total P (by 18-48%) and soluble P (by 44-109%) than spring application, in particular in relatively low precipitation years. For all seasonal application timings, total P loss can be substantially reduced through better site targeting (by 34-43%), improving non-growing season soil cover (by 35-55%), and reducing manure application rates (by 12-30%). At the watershed level, application of all manures in spring (12-month storage) reduced soluble P loss by 9%, but total P loss by only 1% compared to fall and spring application (6-month storage) or four season application (3-month storage) as well as the baseline (with mixed storage capacities across the watershed). The results point to needs of adopting measures to reduce P losses associated with winter and fall applications to improve local water quality, but ban of winter and fall applications by adopting 12-month storage across the watershed brings trade-offs between reduction in soluble P loss and increase in peaks of soluble P concentration in spring at the watershed outlet.