Estimating plant-available nutrients with XRF sensors: Towards a versatile analysis tool for soil condition assessment
Tiago Rodrigues Tavares,
Budiman Minasny,
Alex McBratney,
Maurício Roberto Cherubin,
Gabriel Toledo Marques,
Marcos Mantelli Ragagnin,
Elton Eduardo Novais Alves,
José Padarian,
José Lavres,
Hudson Wallace Pereira de Carvalho
Affiliations
Tiago Rodrigues Tavares
Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil; School of Life and Environmental Sciences & Sydney Institute of Agriculture, The University of Sydney, NSW, Australia; Corresponding authors at: Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil.
Budiman Minasny
School of Life and Environmental Sciences & Sydney Institute of Agriculture, The University of Sydney, NSW, Australia
Alex McBratney
School of Life and Environmental Sciences & Sydney Institute of Agriculture, The University of Sydney, NSW, Australia
Maurício Roberto Cherubin
Department of Soil Science, “Luiz de Queiroz” College of Agriculture, University of Sao Paulo, 11 Páduas Dias Avenue, Piracicaba, Sao Paulo 13418-900, Brazil
Gabriel Toledo Marques
Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil
Marcos Mantelli Ragagnin
Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil
Elton Eduardo Novais Alves
Chair of Soil Science, College for Sustainable Agriculture and Environmental Science, Mohammed VI Polytechnic University, BenGuerir 43150, Morocco
José Padarian
School of Life and Environmental Sciences & Sydney Institute of Agriculture, The University of Sydney, NSW, Australia
José Lavres
Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil
Hudson Wallace Pereira de Carvalho
Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil; Chair of Soil Science, College for Sustainable Agriculture and Environmental Science, Mohammed VI Polytechnic University, BenGuerir 43150, Morocco; Corresponding authors at: Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, São Paulo 13416000, Brazil.
The timely diagnosis of plant-available soil nutrient contents is crucial in enhancing agricultural intensification and bridging yield gaps. There is a global demand for a practical and easy-to-use analytical tool capable of predicting the nutrient status of agricultural soils to make the soil chemical diagnosis faster, cheaper, and environmentally friendly. A growing body of research has highlighted the potential of energy dispersive X-ray fluorescence (XRF) sensors for monitoring the condition of agricultural soils. This study critically reviews current knowledge on the feasibility of using XRF sensors and suggests ways forward to predict plant-available soil nutrients. The review finds that some challenges need to be addressed, including: (i) mitigating the matrix effect in XRF spectral libraries and (ii) calibrating models that can capture the local context of the ratio between total and available nutrient content (T/A ratio). This study further discusses knowledge gaps related to the abovementioned challenges and proposes the following future research areas: (i) understanding the impact of soil management on the temporal stability of T/A ratio and XRF model performance; (ii) assessing advanced predictive modelling strategies to address the challenges related to XRF spectral libraries, i.e., to deal with matrix effect and local context of the relationship between total and available content of nutrients, and (iii) evaluating data acquisition and modelling strategies that optimize the in situ application of portable XRF. Understanding these points is critical to advancing the technological maturity of predicting available nutrients in situ to fulfil plant nutrient requirements along with its development. Finally, portable, easy-to-use analytical tools are key to enhancing soil health/condition monitoring and proposing best management practices in agricultural areas worldwide, particularly in regions with limited infrastructure of soil laboratories. Soil monitoring is critical to preserve, sustain and recover soil condition/health, one of the main manageable drivers of soil and food security.
