Exploring alternate methods for predicting sorption-desorption parameters for environmental phosphorus loss assessment in poultry litter impacted soils

Authors: CHAKRABORTY, S - Auburn University; PRASAD, RISHI - Auburn University; Watts, Dexter; Torbert, Henry - Allen; KAUR, G - Auburn University

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2022
Publication Date: 6/11/2022
Citation: Chakraborty, S., Prasad, R., Watts, D.B., Torbert III, H.A., Kaur, G. 2022. Exploring alternate methods for predicting sorption-desorption parameters for environmental phosphorus loss assessment in poultry litter impacted soils. Journal of Environmental Management. 317(2022):115454. https://doi.org/10.1016/j.jenvman.2022.115454.

Interpretive Summary: Phosphorus (P) is an essential nutrient for plant growth, but repeated application of poultry litter in highly weathered soils can causes soil P accumulation and is a major environmental concern. Much remains unknown about the distribution of inorganic P and organic P forms along with P retention and release characteristics in soils that have long term history of poultry litter application. In this study, we determined the environmental P loss risk of poultry litter impacted soils by investigating the distribution of P forms, and the relationship between sorption-desorption parameters of P. Soil samples from the Piedmont region were collected and P forms were determined using sequential P fractionation. Phosphorus retention properties of the soils were determined using Langmuir isotherm and the P saturation ratio of the soils was determined using oxalate extract (PSROx). There was a strong relationship between sorption-desorption parameters and PSROx. Based on this relationship, PSROx can be used effectively to predict the sorption-desorption parameters of a particular soil type under site specific conditions and replace the laborious traditional batch isotherm.

Technical Abstract: Phosphorus (P) is an essential nutrient for plant growth. Repeated application of poultry litter (PL) in highly weathered soils causes soil P accumulation and is a major environmental concern. Much remains unknown about the distribution of inorganic P (Pi) and organic P (Po) forms along with P retention and release characteristics in soils that have long term history of PL application. Soil test indicator such as P saturation ratio (PSR: ratio of P/[Al + Fe], all elements expressed in moles) can be used effectively to determine environmental P loss risk. In this study, we determined the environmental P loss risk of PL impacted soils by investigating the distribution of Pi and Po forms, P sorption-desorption parameters, soil PSR, and the relationship between sorption-desorption parameters with PSR. Soil samples from soils belonging to the Piedmont region were collected and separated into four depths (0-5, 5-15, 15-30, and 30-45 cm). The P forms were determined using sequential P fractionation. Phosphorus retention properties of the soils were determined using Langmuir isotherm and the PSR was determined using oxalate extract (PSROx). Surface 0-5 cm soils had significantly higher concentration of labile Pi, intermediately available Pi, organic Po forms, along with higher equilibrium P concentration (EPC), and lower Langmuir sorption maxima (Smax) compared to the lower depths. Phosphorus desorbed expressed as a percentage of newly sorbed P (PDES) was negatively related to Smax. Higher PSROx along with low Smax in the surface soils compared to soils in lower depth indicated saturation of the P sorption sites resulting from repeated PL application. There was a strong relationship between sorption-desorption parameters and PSROx. Based on this relationship, PSROx can be used effectively to predict the sorption-desorption parameters of a particular soil type under site specific conditions and replace the laborious traditional batch isotherm.