Broad nutrition resources are outlined in the Agronomists Toolkit. Specific nutrient categories are listed below:



Constraint - Phosphorus 

Plant use

  • Phosphorus is a macronutrient

  • Phosphorus has a key role in energy storage and transfer

  • As such is essential for all growth processes 

  • Phosphorus deficiency in canola is often transitory and compounded by dry soil with symptoms disappearing when topsoil is re-wet following rainfall


  • Deficiency most commonly shows as smaller plants with similar shaped leaves

  • From stem elongation the main stem is thinner and branching is restricted

  • Flowering time and pod numbers are reduced

  • Severely deficient plants develop a narrow purple margin of the leaf blade that spreads inwards

  • The leaf turns bronze before dying


  • Yield penalty can be severe if deficiency is great and left untreated

  • in severe cases the plant may die


Plants have a high requirement for phosphorus during early growth. As phosphorus is relatively immobile in the soil, topdressed or sprayed fertiliser cannot supply enough to correct a deficiency in crop. Soil and tissue tests can be taken and the deficiency can be corrected for the following seasons by application of the correct amount of phosphorus fertiliser.

Links and Resources

AOF - Canola nutrition. Phosphorus

Page 4 of 8. Introduction, application rates, suggested fertiliser rates, common practice fertilising methods, soil testing, and effects on oil content.

AOF - Nutrition. Phosphorus

Sections 5.1, 5.2, and 5.5 of a 6 page PDF. Information on deficiency symptoms, the placement and timing of fertiliser applications, and general information about canola needs for phosphorus. Published 2006.

DEPI VIC - What nutrients do plants require? Phosphorus

Section 6.3.2. Plant uses of phosphorus, deficiency symptoms, and the phosphorus cycle. Page last updated 2013.

GRDC - Best Practice Management Guide. Phosphorus

Page 34 of 92. Role and deficiency symptoms, fertiliser placement, and phosphorus requirements. Published 2009.

GRDC - Crop nutrition fact sheet. Phosphorus

4 page PDF, 'Phosphorus management for the Southern region". Key points, introduction, soil testing, commercial soil tests, responsive soils, fertiliser application, liquid versus granular, and economics. PUblished 2012.

IPNI - Canola 4R Guide. Phosphorus

Pages 13-15 of 21. General introductory information, the right time and place for P, the right P source, and the right P rate. Published 2013.