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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #366844
Title: Impacts of cover crops and crop residues on phosphorus losses in cold climates: A Review

Author
item LIU, JIAN - University Of Saskatchewan
item MACRAE, MERRIN - University Of Waterloo
item ELLIOTT, JANE - Environment And Climate Change Canada
item BAULCH, HELEN - University Of Saskatchewan
item WILSON, HENRY - Agri Food - Canada
item Kleinman, Peter

Submitted to: Journal of Environmental Quality
Publication Type: Review Article
Publication Acceptance Date: 5/27/2019
Publication Date: 6/27/2019
Citation: Liu, J., Macrae, M.L., Elliott, J.A., Baulch, H.M., Wilson, H.F., Kleinman, P.J. 2019. Impacts of cover crops and crop residues on phosphorus losses in cold climates: A Review. Journal of Environmental Quality. 48(4):850-868. https://doi.org/10.2134/jeq2019.03.0119.
DOI: https://doi.org/10.2134/jeq2019.03.0119

Interpretive Summary: Cover crops are an integral component of agricultural conservation systems, helping to protect soil and even to conserve nutrients. The benefits of cover crops, however, are not universal. This review of the science of cover crop effects on phosphorus cycling in cold climates highlights significant trade-offs. While cover crops clearly help to prevent erosion and associated losses of sediment-bound phosphorus in cold climates, they regularly increase the potential for dissolved phosphorus.

Technical Abstract: Abstract The use of plants in riparian buffers or cover crops is widely proposed as a strategy to mitigate sediment and nutrient losses from land to water. In cold climates, concerns may arise with regard to potentially elevated phosphorus (P) losses associated with freeze-thaw of plant materials. Here, we review the impacts of cover crops and crop residues on P loss in cold climates, exploring linkages between water extractable P (WEP) in plant materials and P loss in surface runoff and subsurface drainage. Concentrations of WEP in cover crops ranged from 0.02 g kg-1 dry matter in crop residues to 1.40 g kg-1 in brassica cover crops after one freeze-thaw cycle (FTC), and 0.04 to 2.79 g kg-1 after repeated FTCs, which were equivalent to 5-29% and 15-58% of the plant total P, respectively. In addition to freezing regimes, the large range of WEP concentrations depended upon crop species and hardiness. However, the crop-derived P loss that was measured in surface runoff and subsurface drainage was much lower than WEP, owing to soils’ retention of P by 45% to >99%. In general, cover crops and crop residues effectively prevented soil erosion and loss of particulate P during non-growing seasons in erosive landscape but tended to elevate dissolved P loss in non-erosive soils. Their impact on total P loss was inconsistent across studies and complicated by soil, climate, and management factors. More research is needed to understand interactions between soil, plant, hydrology, and management in influencing P loss, and to improve the assessment of crop contributions to P loss in field settings of cold climates. Further, trade-offs between the concern over P and the control of sediment loss and nitrogen leaching should be acknowledged, as should the uncertainties around freezing and crop adaptability under future climate regimes.