Document Type

Article

Publication Date

12-16-2024

Journal Title

Crop & Pasture Science

ISSN

ISSN: 1836-0947, eISSN: 1836-5795

Keywords

Colwell P, DGT-P, fertiliser, PBI, phosphorus, rainfall, soil analysis, wheat

Disciplines

Agricultural Science | Agronomy and Crop Sciences

Abstract

Context

Current decision support systems (DSS) for phosphorus (P) fertiliser were developed using data from historical cropping systems. An understanding of how soil properties and rainfall influence wheat (Triticum aestivum) response to P fertiliser in current systems is required to optimise P management. Aims

The aims of this study were to: (1) assess the soil properties that have the greatest influence on relative yield; (2) examine how rainfall conditions influence relative yield; and (3) examine whether there were interactive effects between rainfall and soil properties on relative yield. Methods

Forty P rate-response field experiments were completed in Western Australia. Regression tree modelling, soil test calibration curves and the sliding window approach were used to examine relationships between soil properties or rainfall and relative yield. Key results

Phosphorus buffering index (PBI) was important for determining the factors that influence relative yield. For sites with PBI 0–10 cm <56 (n = 30), regression tree modelling showed rainfall before sowing and soil pHCa were important factors (R2 = 0.59). For sites where PBI >56 (n = 10), relative yield was closely related to plant-available P at 0–10 cm and the r-value for the calibration curve was 0.95. Conclusions

Rainfall and soil pHCa influence wheat response to P where PBI <56 is attributed to an accumulation of soil P after decades of fertiliser applications and the availability of stored soil P to crops. Implications

Pre-sowing rainfall should be included in DSS so that grain producers can make informed, tactical decisions about P fertiliser applications for wheat at sowing.

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Digital Object Identifier (DOI)

https://doi.org/10.1071/CP24295