Cross-linked polymers increase nutrient sorption in degraded soils

Lentz, R.D. and Ippolito, J.A. (2021) Cross-linked polymers increase nutrient sorption in degraded soils. Agronomy Journal. 113(2):1121-1135. 1 March 2021.

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Abstract

Cross-linked polymer hydrogels, such as polyacrylamide co-polymer (XPAM) or polyacrylate (XPAA), can alter soil chemistry and crop nutrient uptake but the persistence of these effects has been little studied. This 9-y, irrigated, outdoor pot study evaluated a single, one-time addition of XPAM or XPAA at 0.25% or 0.5% dry wt. (5.6 or 11.2 Mg ha-1) in a degraded calcareous silt loam. Controls included an unamended degraded soil and an unamended, non-degraded soil (i.e. topsoil). Soils were hand-tilled and planted to crops each year. We measured nutrients in soil and leachate water each year, and in the first 5 y, crop yields and nutrient uptake. Both hydrogels increased average soil pH and electrical conductivity (EC), soil extractable K, Na, and TOC, and decreased soil extractable Mg relative to the control. Unlike XPAM, XPAA produced a greater increase in soil extractable K, increased extractable Fe, Zn, Mn, and Cu, increased Olsen P, and decreased total inorganic C. Neither hydrogel affected crop yields but XPAA increased K and Zn and decreased Mg and Na uptake in crops compared to controls. Relative to the control, both hydrogels decreased cumulative Ca, Mg, and S leaching mass losses and increased mean EC of leachate. Unlike XPAM, XPAA increased cumulative leaching mass losses of K, P, NO3-N, and NH4-N relative to the control. The hydrogels’ soil effects persisted for greater than or equal to 7 years and their effect differed as a function of the quantity of included counterions and the stability of the gel structure after soil placement.

Item Type:	Article
NWISRL Publication Number:	1704
Subjects:	Polyacrylamide (PAM) > Cross-linked (hydrogel) PAM Soil > Soil quality Soil
Depositing User:	Users 6 not found.
Date Deposited:	19 May 2021 17:44
Last Modified:	20 Oct 2021 00:15
Item ID:	1742
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1742