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Twizel, New Zealand
Conducted by
AgScience Research

Twizel, New Zealand, multi-year trial

BioAg New Zealand commenced multi-year pasture trials in 2021 in the in low rainfall high-country of the Mackenzie Basin near Twizel, located in the South Island of New Zealand.

Trial aim

Previous research and market perception is that Reactive Phosphate Rock (RPR) fertilisers are only effective in year one where rainfall is above 850mm, or by year 4 when rainfall is over 700mm.

In addition, there is a prevailing view that applying lime with RPR fertilisers will make the RPR ineffective as a fertiliser.

This trial is to evaluate the effectiveness of BioAgPhos (a RPR based fertiliser) in a low rainfall environment and when used with lime.

Final results

BioAg applications significantly increased dryland pasture production (P < 0.008).

S&S applied alone progressively increased yield with application rate up to 17% above untreated grassland. BAP alone increased production by 60%. S&S addition further increased production: 4L/ha increased yield by 120% (P < 0.018) and BAP with 8L/ha gave an 110% increase (P < 0.08). BAP with 12l/ha gave a 75% increase but high experimental variability limits the precise comparison of rate effects.

Dryland Plots
Figure 1 Dryland Plots May 2021, Nov 2021 and Jan 2022
January 2022 harvest results overview – increased Dry Matter yields
Figure 1 Dryland Plots May 2021, Nov 2021 and Jan 2022


The trial results provide statistically significant growth and yield response when applying BAP as a fertiliser.

In the trials, rainfall was below 520mm for the period, and lime was used in conjunction with BAP.

Current market perceptions that a phosphate rock fertiliser is not viable with less than 600mm of rain or in conjunction with lime, are countered through this trial.

BioAgPhos has shown to provide statistically significant growth and composition responses.

Addition of Soil & Seed over fertilised plots increased production compared to the untreated and non-fertilised plots.

For the full reports conducted by AgScience, download here.

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Download independent trial

For the full trial, including methods, results and conclusion, download here.