Phosphorus in soils of riparian and non‐riparian wetland and buffer strips in the Waikato area, New Zealand

Abstract This paper examines the potential for phosphorus (P) release from intensively grazed pasture to waterways. In particular it describes the P release processes occurring in riparian buffer strips. Soil samples at three depths (0–2.5, 2.5–7.5, and 7.5–15 cm) were collected from riparian buffer strips, including wetland and non‐riparian areas at three pasture sites. These soil samples were analysed for total P, plant available P as measured by Olsen P, and soil solution P as measured by 0.01M CaCl2‐extractable P. The P retention capacity and P buffering capacity of the riparian soils were also measured. A significant relationship was found between Olsen P and 0.01M CaCl2‐extractable soil P, indicating that soils with a high plant available P pool (measured as Olsen P) potentially have a high P loss in subsurface flow (as represented by CaCl2‐extractable P). All of the CaCl2‐P concentrations in the top 2.5 cm soil depth at the study sites were higher than the threshold concentration (0.01 mg CaCl2‐P l...