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Philippa McVeagh

Doctor of Philosophy
Study Completed: 2019
College of Sciences


Thesis Title
Prediction of soil Olsen P through mixed pasture leaf tissue biophysical and biochemical properties, topography and farm management in New Zealand hill country

Read article at Massey Research Online: MRO icon

In New Zealand hill country, soil Olsen Phosphorus (Olsen P) is used to decide rates to which aerial applications of phosphate fertilisers are made. Current soil sampling techniques provide spatially sparse information and limit the ability to tailor fertiliser plans to account for within farm variability. A multi-site, multi-seasonal database was used to develop a model to make continuous predictions of phosphate availability in the soil across whole farms. Miss McVeagh’s research used leaf tissue nutrient concentration and biophysical characteristics of mixed pasture, along with topography and fertiliser history to make predictions of soil Olsen P. A hierarchical model improved the predictions compared to a benchmark approach and estimates of soil Olsen P can be made on locations and time points outside of the dataset with a known level of uncertainty. This model can be used in predictive soil mapping to produce maps of soil Olsen P across hill country farms.

Professor Ian Yule
Dr Alister Metherell
Professor Peter Kemp
Professor Mark Bebbington