Impacts of Cover Crops and Crop Residues on Phosphorus Losses in Cold Climates: A Review. Issue 4 (1st July 2019)

• Record Type: Journal Article
• Authors: Liu, Jian; Macrae, Merrin L.; Elliott, Jane A.; Baulch, Helen M.; Wilson, Henry F.; Kleinman, Peter J.A.
• Is Part Of: Journal of Environmental Quality. Volume 48:Issue 4(2019)
• Page Start: 850
• Page End: 868
• Publication Date: 2019-07-01
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.2134/jeq2019.03.0119
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract : The use of cover crops and crop residues is a common strategy to mitigate sediment and nutrient losses from land to water. In cold climates, elevated dissolved P losses can occur associated with freeze–thaw of plant materials. Here, we review the impacts of cover crops and crop residues on dissolved P and total P loss in cold climates across ∼41 studies, exploring linkages between water‐extractable P (WEP) in plant materials and P loss in surface runoff and subsurface drainage. Water‐extractable P concentrations are influenced by plant type and freezing regimes. For example, WEP was greater in brassica cover crops than in non‐brassicas, and increased with repeated freeze–thaw cycles. However, total P losses in surface runoff and subsurface drainage from cropped fields under cold climates were much lower than plant WEP, owing to retention of 45 to >99% of released P by soil. In cold climatic regions, cover crops and crop residues generally prevented soil erosion and loss of particle‐bound P during nongrowing seasons in erodible landscapes but tended to elevate dissolved P loss in nonerodible 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 these factors and plant type that influence P loss, and to improve the assessment of crop contributions to P loss in field settings in cold climates. Further, tradeoffs between P loss and the control of sediment loss and N leaching by plants should be acknowledged. Core Ideas: Winter crop covers reduce soil erosion but may enhance dissolved P loss under cold climates. In cold climates, freeze–thaw cycles increase dissolved P release from plants and soils. Plant water‐extractable P varies with crop species, hardiness, and freeze regimes. Phosphorus losses in runoff and leaching are complicated by soil, hydrology, and management. Assessment of crop impacts on P loss should consider tradeoffs and future climates.