Abstract
ABSTRACT: Spectroscopic techniques have great potential to evaluate soil properties. However, there are still questions regarding the applicability of spectroscopy to analyze soil phosphorous (P) availability, especially in tropical soils with low nutrient contents. Therefore, this study evaluated the possibility to estimate P availability in soil and its pools (labile, moderately labile and non-labile) via Vis-NIR spectroscopy based on intra-field calibration. We used soils from two different locations, a plot experiment that received application of phosphate fertilizers (Field-A) and a cultivated field where a grid soil sampling was performed (Field-B). We used the technique of diffuse reflectance in the visible and near-infrared (Vis-NIR) to obtain the spectra of soil samples. Predictive modeling for P availability and labile, moderately labile and non-labile pools of P in soil were obtained via partial least squares (PLS) regression; classification modeling was performed via Soft Independent Modeling of Class Analogy (SIMCA) on three P availability levels in order to overcome the limitation on quantifying P via Vis-NIR spectroscopy. We found that isolating P contents as the only variable (Field-A), Vis-NIR spectroscopy does not allow estimating P pools in the soil. In addition, quantification of P available in the soil via predictive modeling has limitations in tropical soils. On the other hand, estimating P content in soil through classes of availability is a feasible and promising alternative.
Highlights
Phosphorous (P) supply to plants is an essential factor to ensure proper crop development and high yields (Ziadi et al, 2013)
Predictive modeling for P availability and labile, moderately labile and non-labile pools of P in soil were obtained via partial least squares (PLS) regression; classification modeling was performed via Soft Independent Modeling of Class Analogy (SIMCA) on three P availability levels in order to overcome the limitation on quantifying P via visible and near-infrared (Vis-NIR) spectroscopy
We found that isolating P contents as the only variable (Field-A), Vis-NIR spectroscopy does not allow estimating P pools in the soil
Summary
Phosphorous (P) supply to plants is an essential factor to ensure proper crop development and high yields (Ziadi et al, 2013) In tropical soils, such as Oxisols, phosphate fertilization generally requires attention due to adsorption reactions of the element with soil constituents, which become a drain instead of a source of P for plants (Barbieri et al, 2009; Novais and Smyth, 1999). The methodologies commonly used are based on sequential extractions with chemical reagents (e.g. Hedley fractionation - Hedley et al, 1982); this laboratory procedure is time-consuming, expensive, laborious and susceptible to mistakes (Cécillon et al, 2009) In this context, Vis-NIR spectroscopy is a promising approach to evaluate soil properties, because a single measurement allows inferring several properties (Nocita et al, 2015; Soriano-Disla et al, 2014; Wetterlind et al, 2008). Questions remain regarding applicability of Vis-NIR spectroscopy to analyze P in the soil, especially in tropical soils with low content of organic P, due to its low P availability and the complexity of P interactions with the minerals in this soil type
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
