Soil Phosphorus Desorption Kinetics and Its Relationship with Plant Growth

Abstract

The kinetics of P desorption in soils is important to consider from a plant nutrition perspective. This study was designed to compare the ability of several equations to describe P desorption kinetics from soils and to relate the information derived from desorption kinetic curves to plant growth and P uptake. Samples of five soils (Psammentic Paleudult, Typic Calciustoll, Udic Pellustert, Vertic Albaqualf, and Aridic Calciustoll) were treated with five P levels (0, 25, 50 75, and 100 mg kg−1) and incubated at field capacity and 24 °C for 31 d. Phosphorus desorption kinetic data for each treatment were generated by equilibrating suspensions of the incubated soil samples with mesh bags containing HCO−3‐saturated anion‐exchange resin for periods up to 96 h. Desorbed P was then determined by extraction of resin P with 0.5 M NaC1. Initial (after 0.25 h) and final (after 72 h) amounts of desorbed P and desorption rates were determined. The kinetic data were best described by the expanded form of the Elovich equation. The initial and final amounts of desorbed P were closely related to relative plant growth and P uptake. The final desorbed soil P was the best soil P availability index. Soil P desorption rates generally had soil‐specific relationships with growth of corn (Zea mays L.) and P uptake and did not seem to limit the P nutrition of plants. The parameters of the expanded Elovich equation were not satisfactory indicators of the P‐supplying capacity of the soil.

Evaluation of Kinetic Approach in Describing Potassium Bioavailability

“…These results agree with those of [25], [26], [28], their results on phosphate showed that both constants were related to the P supplying power of soil and or the rate of P release from soil had significant relationship between β and P bioavailability to sorghum did not establish that P dissolution is a rate determining step to P-uptake since similar relationship existed between β and equilibrium ion.…”

“…The correlation coefficient was highly significant with the kinetic parameters representing the rate of K release in the order: The modified Freundlich rate coefficient (K d ) (r = 0.98**) > the rate constant (β) in the Elovich equation (r = 0.97***) > the rate of K release coefficient (R) in the parabolic diffusion (r = 0.96**) > the initial rate of K-release (q 0 ) in 1 st order equation (r = 0.85**). The β coefficient in Elovich which was found to be inversely correlated with the K supplying power of the soil [ [25][26][27][28][29], and inversely related to the rate of K release from soil [26][27][28][29][30] was inversely correlated with the plant K uptake (r = 0.97 ** ). It should be recalled that both Elovich and modified Freundlich equations offered the best fit to the K release data from the tested adequate fit to the description data, its rate of diffusion coefficient (R) gave the high correlation coefficient with the cumulative K uptake and with the uptake of K. Similarly the first-order equation offered a lower fit to the K release data but the rate constant k 0 of the equation was highly correlated with plant K uptake.…”

Phosphorus desorption kinetics in two calcareous soils amended with P fertilizer and organic matter

“…Soil P desorption to solution was likely controlled by a combination of Fe (strengite), AL (variscite), and Ca (hydroxyapatite) complexes (McDowell and Sharpley 2003). Also the calcareous soils generally desorbed more P than the acid soils (Raven and Hossner 1994). Crops growing in large region of the world's agricultural soils respond to phosphate fertilization (Bohn et al 1985).…”

Aspects of phosphorus transfer from soils in Europe

“…Various analytical methodologies have been tested during the last decades in order to study the available-P status of soils, including chemical extraction (Bowman et al, 1978;Holford, 1980;Matar et al, 1988), anion-exchange resins (Sen Tran et al, 1992;Raven and Hossner, 1994), cationanion-exchange resins (Dalal, 1985;Somasiri and Edwards, 1992), resin membranes (Mallarino and Atia, 2005;Forge et al, 2008;Mason et al, 2008), ferrihydrite-impregnated paper strip (Menon et al, 1989), goethite in dialysis membrane (Delgado, 1996;Delgado and Torrent, 1997), isotopic exchange (Morel and Planchette, 1994;Frossard et al, 1994;Bühler et al, 2003), and electro-ultrafiltration (Simard and Sen Tran, 1993). The main limitation in studying the available-P pool in soils has been the absence of a general method adequate for wide application: depending on the dominant P forms in soils, the relationship between P extracted by plants (available P) and P extracted in the lab is different (Mallarino, 1997).…”