Phosphorus/PRI Trials

These trials were established to verify the efficacy of the PRI soil test that we use, and compare it to the Reactive Iron Test that is used by our largest competitor.

Summit Fertilizers Trials

In both cases the response was much greater than that predicted by the reactive iron test. On both sites the Reactive Iron test predicted a response to only 6kg/ha of P. Both sites, in fact, responded up to 40kg/ha P as predicted by the PRI test. In effect the Reactive Iron test predicted that these soils were low Phosphorus absorbing soils, whereas the PRI test predicted that they were high fixing soils.

The Reactive Iron test did not take into account that these Eastern Wheatbelt soils are high in calcium, which can absorb Phosphorus.

PRI Trials

The following trials examined a theory that Phosphorus is readily absorbed in high P fixing soils and therefore there may be some positional unavailability where top dressing and deep banding practises are used.

Phosphorus Placement Trials