Portable X-ray Fluorescence Analysis of Organic Amendments: A Review

Abstract

Portable XRF spectrometry (pXRF) has recently undergone significant technological improvements and is being applied in a wide range of studies. Despite pXRF advantages, this technique has rarely been used to characterize organic amendments and residues. This article reviews those studies undertaken to date in which pXRF is used to characterize these products. Published studies show that pXRF correctly measures elements such as Fe, Pb, Zn, Mn, Ca, and K but gives conflicting results for elements such as Cr, Ni, and As. Among the reasons that may cause the low performance of the technique with certain elements or under certain measurement conditions would be the inadequacy of the analytical comparison procedures used (i.e., digestion with aqua regia), the lack of knowledge of the interfering effects of organic matter, and sample moisture on the XRF signals and the need for a standardized protocol for performing the measurements. However, the speed and low cost of the procedure forecast a greater future use of this technique, especially in cooperation with other fast spectroscopic techniques based on near-infrared (NIRS) or mid-infrared (MIR) spectroscopies. Chemometric procedures based on one or more of these techniques will allow the prediction of elements below the detection limit of pXRF instruments (Cd, Hg), or other properties of organic amendments (organic matter, N, electrical conductivity, cation exchange capacity).

Forest Industrial Waste Materials Upgraded to Fertilizer Pellets for Forest Soil

“…Kennewick, USA. The use of pXRF has been shown to be an easy way to measure nutrients in, for instance, soil [48] and organic waste [49] with relatively good accuracy. An S1 Titan 800 was used to scan each sample with a configuration called soil mode.…”

“…In the event of a changed process or increased production, this should be investigated and considered. Also, a large amount of organic material and moisture content might, according to the literature [49], affect the accuracy of the results. To avoid this source of error, the samples should be dried before they are measured.…”

2023 atomic spectrometry update – a review of advances in X-ray fluorescence spectrometry and its special applications

“…In particular, an understanding of the depth of the XRF spectrometry excited volume, of the interpretation of data close to LODs and of factors that could affect the uncertainty budget was considered to be important for avoiding errors in the use of XRF spectrometry data. Lopez-Nunez 65 reviewed studies on the characterisation of organic amendments and residues in which portable XRF spectrometry was used. Whereas elements such as Ca, Fe, K, Mn, Pb and Zn could be measured correctly, that was not the case for elements such as As, Cr and Ni.…”

Suitability of Volcanic Ash, Rice Husk Ash, Green Compost and Biochar as Amendments for a Mediterranean Alkaline Soil

“…Thus, Table 2 comprises the average concentrations obtained for these trace elements in the amendments, soils and harvested plants for each treatment, as well as the permissible maximum levels set by the European Union [33] and the World Health Organization/Food and Agricultural Organization [34]. Concerning the amendments, the concentrations of As, Cd, Cr, Cu, Pb and Zn were always below the maximum allowable concentrations in soil ameliorants as established by the European regulations [20,21] and consequently, in terms of trace elements, it can be inferred that they are safe to use. Nevertheless, it should be stated that VA amendment has significantly greater concentrations of Cr, Cu, Ni, Pb, and Zn than the rest of the amendments.…”

“…There is no doubt that inorganic and organic waste own a high potential as raw material to mitigate problems that seriously affect the environment and agriculture in the Mediterranean Basin, such as soil loss due to erosion, lack of organic matter, and the need of mineral fertilizers. However, prior to the application of any soil amendment, safety has to be ensured by monitoring the abundance of non-biodegradable trace elements, including As, Ba, Cd, Cr, Li or Pb, classified as persistent toxic elements and that may result toxic for plants, animals and human [20,21]. Thus, in the absence of data on the application of these residual materials, alone or in combination, on Mediterranean calcareous agricultural soil, the primary goal of this research was to investigate the effects of a variety of organic and inorganic amendments derived from residues on the physical characteristics, composition, and growth of barley in a calcareous soil.…”