Kinetics of Phosphorus Supply Measured by Anion Exchange Resin

G. FÜLEKY, L. TOLNER and J. DÖMSÖDI

Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences and Budapest Chemistry Works, Budapest

Summary

It has been determined by anion exchange resin in four soil types of Hungary, that phosphorus gets into soil solution with three simultaneous first order reactions:

P_t = C₁ * (1 – e^-k1.t) + C₂ * (1 – e^-k2.t) + C₃ * (1 – e^-k3.t)

In case of P fertilization the maximum amount of phosphorus getting into soil solution with these reactions increases. At the same time the duration of the intermediate reaction also increases. Similarly to the literature the maximum duration of the intermediate reaction lasts about 16 hours.

Table 1. Characteristics of the soi1s. (1) Sampling site and type of the soil, a) Karcag, meadow chernozem, b) Nagykanizsa, brown forest soil, e) Nagyhörcsök, calcareous chernozem, d) Kecskemét, blown sand, (2) Physical soil type: e) clay-silt; f) sandy silt; g) silt; h) sand. (3) Humus, %. P₀ = nonfertilized soil. P = fertilized with phosphorus.

Table 2. Parameters of the regression equations (1) Sampling site of the soil and treatment a) --d) see at Table 1. (2) Rapid reaction (I), (3) Intermediate reaction (II), (4) Slow reaction (III).

Table 3. Phosphorus obtained from the reactions, in %‘ (1) Sampling site of the soi1 and treatment, a)—d) see at Table 1. (2) Reaction. (3) Duration, minutes.

Fig. 1. Kinetics of phosphorus supply of Karcag soil. (I) Rapid reaction, (II) Intermediate reaction, (III) Slow reaction, A. non-fertilized, B. fertilized with phosphorus, Horizontal axis: minutes, Vertical axis: μg P/g soil.