Improving phosphorus availability in Andisols and Oxisols A thesis submitted to The University of Adelaide in fulfilment of the requirements for the degree of Doctor of Philosophy DANIELA FERNANDA MONTALVO GRIJALVA School of Agriculture, Food and Wine The University of Adelaide December 2014 Table of contents Abstract ................................................................................................................................... vii Declaration................................................................................................................................ x Acknowledgements ................................................................................................................. xi List of publications and presentations ................................................................................ xiii Structure of the thesis ............................................................................................................ xv Chapter 1. Introduction .......................................................................................................... 1 References .............................................................................................................................. 6 Chapter 2. Literature review .................................................................................................. 9 Introduction ............................................................................................................................ 9 Phosphorus in the soil .......................................................................................................... 10 Soil solution P................................................................................................................... 10 Soil solid phase P.............................................................................................................. 12 Availability of P to plants – concepts and measurement...................................................... 14 Concepts ........................................................................................................................... 14 Measurement .................................................................................................................... 15 Strongly P-sorbing soils: Andisols and Oxisols ................................................................... 17 Management of P in strongly P-sorbing soils ...................................................................... 19 Plant mechanisms to improve P acquisition ..................................................................... 19 Management practices to improve fertilizer efficiency .................................................... 20 Behaviour of P fertilizers in soils ......................................................................................... 21 Phosphorus fertilizers ........................................................................................................... 24 Current P fertilizer formulations ...................................................................................... 24 Modifying current fertilizer formulations to improve fertilizer P efficiency ................... 26 Nanomaterials ....................................................................................................................... 29 General properties ............................................................................................................ 29 Behaviour of manufactured nanoparticulate nutrients in soils ......................................... 30 iii Potential mechanisms to improve fertilizer efficiency with nanotechnology .................. 33 Aim and specific objectives of this thesis ............................................................................ 35 References ............................................................................................................................ 36 Chapter 3. Fluid fertilizers improve phosphorus diffusion but not lability in Andisols and Oxisols .............................................................................................................................. 47 Statement of authorship ........................................................................................................ 48 Abstract ................................................................................................................................ 49 Introduction .......................................................................................................................... 49 Materials and Methods ......................................................................................................... 50 Results and Discussion ......................................................................................................... 52 Conclusions .......................................................................................................................... 58 References ............................................................................................................................ 58 Chapter 4. Agronomic effectiveness of granular and fluid phosphorus fertilizers in Andisols and Oxisols evaluated by 33P isotopic dilution technique ................................... 61 Statement of authorship ........................................................................................................ 62 Abstract ................................................................................................................................ 63 Introduction .......................................................................................................................... 64 Materials and Methods ......................................................................................................... 65 Results and Discussion ......................................................................................................... 70 Conclusions .......................................................................................................................... 76 References ............................................................................................................................ 83 Chapter 5. Efficacy of hydroxyapatite nanoparticles as phosphorus fertilizer in Andisols and Oxisols .............................................................................................................................. 87 Statement of authorship ........................................................................................................ 88 Abstract ................................................................................................................................ 89 Introduction .......................................................................................................................... 90 Materials and Methods ......................................................................................................... 92 Results ................................................................................................................................. 97 Discussion .......................................................................................................................... 100 References .......................................................................................................................... 110 Chapter 6. Natural colloidal P and its contribution to plant P uptake ........................... 113 Statement of authorship ...................................................................................................... 114 Abstract .............................................................................................................................. 115 Introduction ........................................................................................................................ 116 iv Materials and Methods ....................................................................................................... 118 Results ............................................................................................................................... 122 Discussion .......................................................................................................................... 125 References .......................................................................................................................... 136 Chapter 7. Conclusions and future outlook ....................................................................... 139 References .......................................................................................................................... 146 v Abstract Low phosphorus (P) availability limits plant growth in many soils, particularly in Andisols and Oxisols, due to their large content of minerals that strongly sorb P (e.g. Al/Fe oxyhydroxides, allophane). Because of the strong P retention, P fertilizer requirements are high in these soils. Strategies to increase the efficiency of P fertilizers – and reduce P rates needed to obtain maximal yield – remain key to reducing the pressure on limited rock phosphate reserves. To develop management practices or fertilizer formulations that enhance P availability and fertilizer efficiency in strongly P-sorbing soils, a better understanding of the chemical reactions of P in these soils is needed. This work aimed (i) to examine the chemical behaviour of soil P and added