Thesis
Assessing the agronomic phosphorus fertiliser value of animal manures
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2024
DOI:
https://doi.org/10.25918/thesis.497
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Abstract
Animal manures may offer a sustainable alternative to mineral phosphorus (P) fertilisers derived from finite rock phosphate reserves. This thesis examined the agronomic P fertiliser value of manures compared to monoammonium phosphate (MAP) under different soil conditions and application methods, using wheat as the test crop across glasshouse and field experiments.
Study 1 evaluated three manure types, cattle (CaM), chicken (ChM), and pig manure (PiM), in a low P-sorbing Arenosol and a high P-sorbing Ferralsol. Manures were applied at various rates and either banded or incorporated. In the Arenosol, incorporation enhanced the effectiveness of CaM and PiM, which outperformed MAP in biomass and grain yield. ChM was less effective due to sodium toxicity at high rates. In the Ferralsol, banded MAP and CaM were similarly effective, but post-harvest soil P speciation suggested a higher residual value from CaM.
Study 2 (i) assessed soil-specific P responses across four contrasting soils, Ferralsol, Vertisol, Luvisol, and Arenosol. ChM generally improved biomass and grain yield compared to MAP in the Ferralsol and Vertisol, while MAP was more effective in the Luvisol. No significant differences were observed in the Arenosol, although ChM had a lower critical P requirement for P uptake. Study 2 (ii) evaluated the residual value of ChM and MAP. In the Ferralsol, residual ChM matched fresh MAP and outperformed residual MAP. In the Luvisol, residual treatments produced higher grain yield than fresh MAP, with residual MAP showing greater biomass.
Study 3 employed the reverse dilution ³³P isotope method to quantify fertiliser-derived P uptake. In the Ferralsol, CaM and ChM had significantly higher P recovery than MAP. In the Luvisol, MAP had higher recovery. These differences aligned with soil P buffering capacity.
Study 4 was a field trial in a Ferralsol comparing ChM and MAP. MAP enhanced early-season growth and P uptake, but final biomass and grain yield were similar for both fertilisers. ChM required ~60% more P to achieve 95% of maximum biomass and yield, indicating delayed P availability.
Overall, this research shows that the agronomic value of manures is soil- and time-dependent. Manures can match or exceed MAP performance in some soils, particularly those with high P sorption capacity, though higher application rates may be needed. Findings support targeted use of manure to enhance P efficiency in grain systems.
Details
- Title
- Assessing the agronomic phosphorus fertiliser value of animal manures
- Creators
- Maryam Barati
- Contributors
- Terry J Rose (Supervisor) - Southern Cross UniversityAbe Gibson (Supervisor) - Southern Cross UniversityChelsea Janke (Supervisor) - The University of QueenslandTim I McLaren (Supervisor) - The University of Queensland
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- vii, 160
- Identifiers
- 991013291354002368
- Copyright
- © Maryam Barati 2024
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis