Phosphorus saturation index and water-extractable phosphorus in high-legacy phosphorus soils in southern British Columbia, Canada

Abstract

Understanding of the risk of phosphorus (P) loss to the environment is crucial to monitor soil P and implement policies for P management. We assessed P sorption characteristics and adapted a P saturation index (PSI) for silage corn and blueberry fields in south coastal British Columbia (BC), Canada. We used 284 composite soil samples with contrasting P levels collected from eight silage corn and 23 blueberry fields across south coastal BC. The P sorption maximum (Smax) varied between 982 and 2532 mg P·kg−1 and was influenced by aluminum concentration and organic matter content. The degree of P saturation was related to water-extractable P (Pw) by a quadratic regression with R2 = 0.85. A critical Pw = 3.7 mg·kg−1 was established across the two cropping systems. The silage corn fields with pH > 5.5 had critical PSI value of 10.4%, and blueberry fields with pH < 4.7 had critical PSI value of 18.0%. These results showed that the risk of P loss from soil in the silage corn was high, but it was low for blueberry because the critical PSI for silage corn fields was lower than for blueberry fields, and therefore, saturation would be more easily reached, even though more P is applied to blueberry fields. The combination of a critical PSI and Pw as agri-environmental indicators will help farmers and professionals to identify fields with risk of P loss, to implement a nutrient management plan, and to monitor how this risk changes with time.

Conservation practices modify soil phosphorus sorption properties and the composition of dissolved phosphorus losses during runoff

“…van der Zee et al (1987) report that the risk of soil P loss can be predicted with the single quadratic regression and a critical DPS OX . When soil DPS OX is more than 25%, the loss of dissolved P by runoff water is high (Messiga et al, 2021). However, the linear positive correlation between WSP and DPS OX in this study illustrated that the critical value of DPS OX is smaller than 25% or insufficient amount of data.…”

“…The sum of Al Ox and Fe OX is termed P sorption capacity (PSC, mmol kg −1 ). We used an average α value of 0.5 to calculate DPS OX (van der Zee et al, 1987;Messiga et al, 2021).…”

“…Many previous studies on P sorption characteristics of agricultural soils emphasizes the dominant role of mineral (Al, Fe, Ca), OM content and other soil properties, all of which can increase the capacity of soils to fix newly applied P and thus reduce P loss from soil through (Messiga et al, 2021;Pradhan et al, 2021;Messiga et al, 2011). In this study, compared with conventional tillage, the DPS OX of conservative tillage always increased, regardless of the content of (Fe and Al) OX increased or decreased, thus (Fe and Al) OX may not be the key factor affecting soil DPS OX .…”

“…Among various P forms, dissolved inorganic and organic P are major concerns as they are highly reactive and readily bioavailable for algae growth (Li and Brett, 2013;Van Moorleghem et al, 2013;Jarvie et al, 2017). Thus, reducing the loss of dissolved P from cultivated soils is an essential challenge in the fight against eutrophication of surface water (Pizzeghello et al, 2016;Jarvie et al, 2017;Bol et al, 2018;Ulén et al, 2019;Messiga et al, 2021).…”

Phosphorus Sorption Capacity and Its Relationships With Soil Properties Under Podzolic Soils of Atlantic Canada

“…The mineralogical analysis was conducted for selected samples to identify the dominant mineral phases in long term managed podzolic soils. The extractable (potentially available) P was determined in 1% citric acid (CA) (47), and deionized water (48,49) extracts (1:10 soil to solution ratio) using the ascorbic acid method as described by Murphy and Riley (50) and modified by Watanabe and Olsen (51). Mehlich-3 extractable total P and micro-and macro-nutrients were determined using a Prodigy High Dispersion ICP-OES (Teledyne Leeman Labs, Manson, USA).…”