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ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #416578
Research Project: Developing Agronomically and Environmentally Beneficial Management Practices to Increase the Sustainability and Safety of Animal Manure Utilization

Location: Food Animal Environmental Systems Research

Title: Modeling P release from high P soils at two flow rates

Author
item Bolster, Carl
item Penn, Chad

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/28/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The amount of available soil P for plant uptake and release is often estimated from laboratory extractions of P using water, chemicals, or infinite sinks such as anion exchange resins and iron-oxide strips. These methods, however, usually involve shaking soil with large volumes of solution which can cause abrasion of soil and resorption of P. Moreover, the physical mixing and high solution to soil ratios are not representative of actual in situ conditions. A more representative approach is to measure P release from soils using flow through column experiments. In this study, we conducted flow through column experiments using 22 soils varying in chemical and physical properties. Experiments were conducted at two flow rates and effluent was continually collected using a fraction collector. Effluent P concentrations were fit using a 1-dimensional advection-dispersion equation that included two P pools each with separate first-order kinetic desorption rates. The effluent data for all 22 soils at both flow rates were fit exceptionally well with model efficiencies >0.99. Fitted Q1 values were consistently higher for the slow-flow column with the exception of two soils. There was a strong correlation (r = 0.70) between fitted Q1 values for the fast- and slow-flow columns. Q1 was strongly correlated with oxalate-, Mehlich3-, and water-extractable P with r values > 0.75, 0.68, 0.69, respectively for the fast flow rate and 0.85, 0.81, 0.84, for the slow flow rate. Fitted Q1 values were also strongly correlated with degree of P saturation (r = 0.77 and 0.83). There was minimal (p = 0.11) correlation between k1 values between the two flow rates. Desorption rates for the fast flow columns were greater than for the slow flow columns by factors ranging from 3.4 to 297.