Comparing the risk of phosphorus runoff following single and split phosphorus fertiliser applications in two contrasting catchments using rainfall simulation and Bayesian modeling

摘要

In this study we applied a Bayesian modeling approach to investigate the comparative risk of P runoff following single and split P fertilizer applications in two catchments with contrasting rainfall/runoff patterns. Split P fertiliser strategies are commonly used in intensive pasture production in Australia and our results showed that 3 applications of 13.3 kg P/ha resulted in a greater risk of P runoff compared to a single application of 40 kg P/ha, when rainfall simulation experimental data and long term surface runoff data were combined in a Bayesian P risk model. Splitting P fertiliser applications increased the likelihood of a coincidence of fertiliser application and runoff occurring. We found that the overall risk of P runoff is also increased in catchments where the rainfall/runoff partem is less predictable, compared to catchments where rainfall/runoff is winter dominant. We suggest that land managers apply P fertiliser less frequently and only during periods of the year when surface P runoff risk is low.