Fertilizer effects on phosphorus fractions and organic matter in Andisols

• G Velásquez ^[1] ; M Calabi-Floody ^[1] ; P Poblete-Grant ^[1] ; C Rumpel ^[3] ; R Demanet ^[1] ; L Condron ^[2] ; M.L Mora ^[1]
  1. [1] Universidad de La Frontera

     Universidad de La Frontera

     Temuco, Chile

     
  2. [2] Lincoln University

     Lincoln University

     Nueva Zelanda

     
  3. [3] CNRS Institute of Ecology and Environment of Paris

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• Localización: Journal of soil science and plant nutrition, ISSN-e 0718-9516, ISSN 0718-9508, Vol. 16, Nº. 2, 2016, págs. 294-309
• Idioma: inglés
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• Resumen

  • Andisols are characterized by a high phosphorus (P) fixation capacity, which is a limiting factor for plant production. Continuous application of P fertilizer may result in an accumulation of P associated with soil organic matter (SOM), which further acts to reduce the availability of the added P. The objectives of this study were (1) to evaluate the impact of P fertilizer inputs on the quantities and chemical forms of P, and (2) to investigate relationships between P forms SOM and land use. Topsoil (0-20 cm) and subsoil (20-40 cm) samples were taken from two Andisols series under grassland and arable cropping. Soil P forms were determined using sequential fractionation, while SOM analysis involved a combination of 13C nuclear magnetic resonance (NMR) spectroscopy and pyrolysis-GC-mass spectrometry. Fertilization increased total P, total organic P, organic carbon, and inorganic P fractions, mainly in arable soils. Labile P was higher in grassland (3% of total P) than in arable soils (1% of total P). A clear effect of fertilization was observed on organic matter compounds measured by pyrolysis in both soil depths. Interestingly, the polysaccharide-derived compounds increased in fertilized soils and lipid-derived compounds decreased. Thus fertilization principally affected labile P and labile SOM forms, whereas recalcitrant forms of P and SOM remained unchanged.