Southern Dirt DIRT - Phosphorus efficiency in pastures

Summary

​The aim of this project was to improve phosphorous (P) use efficiency through increased understanding of soil benchmarks and critical soil values and identifying alternative legumes that have lower phosphorous requirements.
In 2014 a group of Southern Dirt producers came together to develop a project around this aim. They wanted to identify if they could grow an alternative legume crop with lower phosphorous rates that would produce more feed with the same or less amounts of P than sub clover. They also wanted to explore if liquid P is a more effective treatment than equal unit of granular P. The group wanted to find out the response from each variety with a sub optimal dose of P. These questions led to the final project objectives:
To compare alternative legume species with potentially lower critical P values with the standard sub-clover currently grown in the Kojonup area.
To evaluate the plant health and biomass of alternative legume species and sub-clover when P is applied in either a liquid or granular form.
To investigate if a lower level of P rather than the recommended rate can still produce as much biomass from pastures.
The treatments used were a combination of low to high rates of P (0, 5, 10, 20, 40, 60kg/ha) which were replicated throughout the trial. The sown species were Yellow Santorini Serradella, Margurita French Serradella, and sub clover (2014 a pasture mix and 2015-16 Dalkeith clover).