Comparing Different Phosphorus Extraction Methods: Effects of Influencing Parameters

Viktória Vona,Csaba Centeri,István Mihály Kulmány,Gergely Jakab,Zsolt Biró,Renátó Kalocsai,Gábor Milics,Attila József Kovács,Jakab Kauser,Márton Vona

doi:10.3390/su14042158

Abstract

The current study compares the phosphorus (P) analysis methods of ammonium lactate (AL), Mehlich 3 (M3); water extraction (P-WA(P)&P-WA(PO4)), cobalt hexamine (CoHex) and X-ray fluorescence (XRF) as an estimate of total soil P. The ratio of the P-content/XRF was first calculated and compared with the whole dataset. Based on the comparison of all the data, there were significant differences between the results of P-WA(P) and P-WA(PO4) vs. M3 and AL, CoHex vs. M3 and CoHex vs. AL methods (p < 0.001). The second step was the analysis of the influencing factors based on their categories for a more in-depth understanding of their role (CaCO3-content, pH, soil texture and clay content). The results showed that higher CaCO3 content (>1%) resulted in lower correlations (6/10 cases). The extraction methods, the soil, the classification method of the soil properties and the statistical analyses affect the evaluation. The dataset covers a good range of the analysed factors for the evaluation of phosphorus in the majority of Hungarian soil types in arable use. There were two methods that detected the largest amount of P from the total P in the soil: AL and M3.

Highlights

At the current utilization rate, it is estimated that the global phosphorous (P) reserve at the current utilization rate will last from 600 to 1000 years [1]
We found that the water-soluble P and PO4 methods yielded similar results, but they all had significant differences against all other methods in all groups of the influencing soil parameters
This study shows that do the well-known extraction methods affect the evaluation of P measurements, but the soil and the chosen classification of the influencing soil parameters affect it

Summary

Introduction

At the current utilization rate, it is estimated that the global phosphorous (P) reserve at the current utilization rate will last from 600 to 1000 years [1]. In the European Union, the Soil Protection Act makes it mandatory for farmers to monitor and maintain adequate levels of soil fertility by regular testing. There is still no common regulation for analytical methods of soil analysis [2,3]. Soils can only be managed sustainably at a global level if sufficient, reliable and comparable information is available. The harmonization of soil analysis methods is important in order to be able to comply with legislation and boundary conditions and assess agricultural sustainability. According to the results of the FAO GLOSOLAN project data, harmonised information is critical in order to compare information and model the P variation between different world areas, on either a regional or global scale [4,5], and to support an appropriate management decision (FAO, Global Soil Partnership)

Methods

Discussion

Conclusion