Key Messages

The key messages we deliver to grain producers will address N, P and K management in grain production, specifically:

  • The impact of soil physical and chemical properties on soil nitrogen supply to crops
  • Which soil or agronomic factors have the greatest influence on crop yield response to N fertiliser
  • The economically-optimum range for N and P dose response curves, informing the level of precision required in N and P rates
  • The most accurate approach to predicting yield response to fertiliser P based on single, or multiple factors
  • The influence of preceding crops and P fertiliser management on plant-available P in the current year
  • The forms of P in WA cropping soils and the implications for soil P supply to crops
  • The most accurate soil test method for plant-available K in WA cropping soils
  • The level of soil K required in loamy soils to avoid deficiency
  • The level of leaching losses of K in WA cropping soils
  • The impact of crop sequence and K application strategy on profit from K fertiliser application.

Project Overview

The evolving cropping sequences in the Western Region require specific advice that improves precision in nitrogen (N), phosphorus (P) and potassium (K) fertiliser decisions. The current body of evidence used to support N, P, and K decisions is inadequate across a range of situations and this uncertainty has led to a lack of confidence in fertiliser recommendations. Decision gaps exist in N, P and K fertilizer management because of climate and systems changes since most crop nutrition knowledge was obtained. Annual winter rainfall has declined and the number and size of rainfall events in autumn has decreased (Hope et al., 2006; IOCI, 2002). Soil P has accumulated across much of the region with a recent survey showing that 70% of soils have soil P levels above the critical concentration for 90% of maximum production (Weaver and Wong, 2011). N and K decisions are problematic and negative balances are common for these nutrients (National Land and Water Resources Audit, 2001).

Project Objectives

The objective of this project is to deliver knowledge that will enable grain producers to maximise the profit they achieve from the application of N, P and K fertilisers to crops. The new knowledge delivered by this project will be draw from a program of research at the laboratory, glasshouse and field scale.

Target Audience

Our ultimate audience is grain producers but the target audience for this project is broad. Industry partners, including fertiliser providers and agronomists, are an important conduit of knowledge from the project to grain producers. The local and national research community is also part of our target audience.

This project is supported by a Grains Research and Development Corporation (GRDC) co-investment. Other funding and in-kind support was provided by the Department of Primary Industries and Regional Development (DPIRD), Murdoch University, The University of Western Australia, and industry partners CSBP and Summit Fertilisers.


Dr Craig Scanlan

Department of Primary Industries and Regional Development

Research Team

The project team operates within and is supported by the SoilsWest alliance. 

  • Craig Scanlan (DPIRD)
  • Daniel Murphy (Murdoch University)
  • Zed Rengel (The University of Western Australia)
  • Richard Bell (Murdoch University)
  • Frances Hoyle (Murdoch University)
  • Raj Malik (DPIRD)
  • Gustavo Boitt (The University of Western Australia)
  • Miao Miao Cheng (Murdoch University)
  • Qifu Ma (Murdoch University)
  • Wayne Pluske (Equii)
  • James Easton (CSBP)
  • Andreas Neuhaus (CSBP)
  • Mark Gherardi (Summit)
  • Louise Barton (The University of Western Australia)
  • Liz Petersen (TPG)


  1. Nutrient-management challenges and opportunities in conservation agriculture LINK
  2. Sodium (Na) Stimulates Barley Growth in Potassium (K)-Deficient Soils by Improved K Uptake at Low Na Supply or by Substitution of K at Moderate Na Supply LINK
  3. pH and exchangeable aluminum are major regulators of microbial energy flow and carbon use efficiency in soil microbial communities LINK
  4. Advances in understanding the potassium cycle in crop production. In: Rengel, Z., (ed.) Achieving Sustainable Crop Nutrition. Burleigh Dodds Science Publishing.
  5. Long-term rundown of soil K reserves in Western Australia requires a re-evaluation of K management in grain production: a review. Accepted LINK (TBA)
  6. Sustainability of nutrient management in grain production systems of south-west Australia LINK