Phosphate Speciation and Citrate-Induced Mobilization of P in an Acric Oxisol |
| |
Authors: | Sheila Renata Santos Dean Hesterberg Luís Reynaldo Ferracciú Alleoni |
| |
Institution: | 1. Institute of Science, Engineering and Technology, Federal University of Jequitinhonha and Mucuri Valley, Teófilo Otoni, Brazil;2. Department of Soil Science, NC State University, Raleigh, NC, USA;3. Department of Soil Science, College of Agriculture Luiz de Queiroz, University of Sao Paulo, Piracicaba, Brazil |
| |
Abstract: | Billions of dollars are spent annually in Brazil on imported phosphorus (P) fertilizers for agricultural crops produced on Oxisols. Phosphate fixation by Oxisols is a main limitation to crop productivity because these highly weathered soils have a high phosphate adsorption capacity. The objective was to determine whether reaction of an Acric Oxisol with citrate increases P availability. Columns of P-amended subsoil material were leached with 1 mM citrate solution, and effluent was monitored. Solid-phase speciation was measured for different stages of leaching using X-ray absorption near edge structure (XANES) spectroscopy at the P K-edge. When soil columns were leached with up to 56 column pore volumes of 1 mM citrate solutions, no P was detected in column effluent samples, whereas aluminum (Al) and iron (Fe) increased up to 30 and 1.4 µmol L?1, respectively. The XANES analysis suggested that with increased leaching, a minor proportion of phosphate adsorbed on Fe-oxides increased as phosphate adsorbed on Al-oxides decreased. The results indicated that citrate tends to induce minor species redistribution of phosphate between Al- and Fe-oxide bound forms, but P mobilization was trivial compared with complexometric mobilization of Fe and Al. |
| |
Keywords: | Citric acid phosphorus P K-edge XANES spectroscopy savanna soil |
|
|