Reducing P Rates

Investigates the potential of high status P soils to withstand long term reduction of P applications at sowing.

FarmLink Research established five sites across the region to investigate the potential of high status P soils to withstand long term reduction of P applications at sowing. Rates of 0, 5, 10 & 20kg P/ha were replicated three times and randomised within the block at each site.

Paddocks were soil tested prior to beginning the project and P was tested using Colwell, Resin, PBI and DGT methodology.  Each treatment is tested prior to sowing every season to determine ongoing status over time for P & N.  Trials began in 2009 and are planned to run until 2013. N response is controlled by applying blanket rates of N if required over the entire site.

Initial results have shown that in originally high P status paddocks, after drought, rates can be reduced considerably without limiting yield.  The aim of the project is to be able to estimate levels of P that will limit yields and apply enough P at sowing to alleviate any potential problems.