engleski

Comparison of two soil phosphorus analyses

The aim of this paper is to compare soil phosphorus extraction by sodium hydrogen carbonate solution (Olsen P) and by ammonium lactate (AL P, the most frequent phosphorus extraction in Croatia) and to create a model for prediction of Olsen P using ordinary soil fertility control data. Soil samples were sampled from 265 sites in Croatia to a depth of 25 cm. Used soil data set includes Olsen P (not included in ordinary soil analyses in Croatia), pH (n KCl), pH (H2O), organic matter, ammonium lactate extracted P and K. Soil pH (n KCl) ranged from 3, 5 to 8, organic matter up to 5%, potassium up to 400 mg kg-1 and phosphorus up to 200 mg kg-1. Olsen P and AL P correlated significantly and difference between them was influenced by soil pH and organic matter. These relations are used for creating a several regression models (include at least 2 and maximum 5 soil quality attributes). Regression models were done regardless to variability of soil analyses data or depending on soil pH and/or organic matter range, which significantly decrease difference between prediction and measured Olsen P (model error). The validation of the model was done with a few completely new data sets by comparison model error with acceptable variation of Olsen P determination repeatability (ISO 11263). The results could be useful for introduction of Olsen P as a data for fertilization recommendation in Croatia.

soil analysis ; phosphorus ; Olsen method ; Egner-Riehm-Domingo method

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