CAHNRS > Washington Oilseed Cropping Systems > Soil Fertility

Soil Fertility

Canola plant.

All essential elements are required in order for canola plants to complete their life cycles. To maximize yield, adequate levels of all essential elements are required. Essential elements are categorized as either macronutrients or micronutrients. Plants require macronutrients in larger quantities than micronutrients. However, micronutrients are just as essential to plants completing their life cycle as micronutrients. The macronutrients of greatest regional importance to canola production are Nitrogen, Sulfur, and Phosphorous. Boron and zinc have been found to be deficient in the region.

Extension Publications

Cover of FS045E.

Canola Growth, Development and Fertility (FS045E)

The purpose of this guide is to summarize current information on canola growth and fertilizer requirements. Canola is a relatively new crop to the Pacific Northwest and little fertility research has been conducted in this region. The information contained in this guide is intended to serve as a reference until the results of ongoing, local research are available. Canola is distinct from wheat in terms of growth habit, nutrient uptake, and nutrient removal in the seed. According to published research and fertilizer recommendations, canola requires more nitrogen and sulfur than wheat to achieve the same yields. Soil test-based requirements for phosphorus and potassium are similar to wheat, but boron requirements are higher. Because canola plant residue is higher in nitrogen and phosphorus than wheat straw, cycling of nutrients from residue to the subsequent crop may be an important rotational benefit of canola.

  • Singh, S., S. Singh, J. Antonangelo, H. Neely, and R. Koenig. 2024. Survey for Soil and Plant Micronutrients in Dryland Canola Production. p. 11. In 2024 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 24-1, WSU, Pullman, WA.
  • Madsen, I.J., H. Tao, and W.L. Pan. 2020. Developing Diagnosis and Recommendation Integrated System for Micronutrients in Spring Canola. p. 24. In 2020 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 20-1, WSU, Pullman, WA.
  • Madsen, I. 2019. Tissue Test and Foliar Applications of Micronutrients to Winter Canola. p. 28. In 2019 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 19-1, WSU, Pullman, WA.
  • Madsen, I.J. and W.L. Pan. 2016. Canola Seedling Root Damage Caused by Ammonium Fertilizers. In 2016 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 16-1, WSU, Pullman, WA.
  • Pan, W., M. Reese, T. Beard, I. Madsen, and T. Maaz. 2016. Do Our Subsoils Provide Wheat and Canola Roots with Ample Water and Nutrients During Grain Filling?. In 2016 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 16-1, WSU, Pullman, WA.
  • Pan, W., A. Hammac, T. McClellan, I. Madsen, L. Graves, K. Sowers, and L. Young. 2013. Oilseed Root Characteristics: Implications for Water and Nutrient Management. In 2013 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech Report 13-1, WSU, Pullman, WA.
  • Pan, W., R. Koenig, A. Hammac, T. McClellan, M. Hughes, J. Rumph, and R. Bolton. 2012. A Change is in the Air: Refining Canola Fertilizer Recommendations. In 2012 Dryland Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech. Report 12-1, WSU, Pullman, WA.
  • Koenig, R., A. Hammac, and W. Pan. 2009. Oilseed Crop Fertility. In 2009 Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech. Report 09-1, WSU, Pullman, WA.
  • Koenig, R., R. Stevens, W. Pan, and A. Hammac. 2008. Canola and Camelina Fertility: Review of Literature and Initiation of New Studies. In 2008 Field Day Abstracts: Highlights of Research Progress. Dept. of Crop and Soil Sciences Tech. Report 08-1, WSU, Pullman, WA.

Visit the Department of Crop and Soil Sciences site to see all the CSS Field Day Abstracts.

  • 2018 Annual WOCS Meeting
    • Canola Root Responses to Management Induced Environmental Stress
      Isaac Madsen
  • 2017 Annual WOCS Meeting
    • Canola Fertility on Fire!
      Tai Maaz, Isaac Madsen, Ashley Hammac, Bill Pan, and Haiying Tao
  • 2017 Oilseed Workshops
    • Fertility Management
      Bill Pan, Isaac Madsen, Don Wysocki, Haiying Tao
    • Brassica Nutrition
      Don Wysocki, OSU
  • 2016 Annual WOCS Meeting
    • Washington Oilseed Cropping Systems Project – History and Future; Soil Fertility and Root Research Update
      Bill Pan, Isaac Madsen, Tai Maaz
  • 2015 PNW Oilseed and Direct Seed Cropping Systems Conference
    • Soil pH Survey Lime Project
      Paul G. Carter, WSU Extension Regional Extension Educator, Dayton, WA and Terry Bruegman, WACD Columbia Conservation District, Dayton, WA
    • Canola and Wheat Seedling Root and Root Hair Behavior in the Presence of Deep-Banded Urea
      Isaac Madsen, William Pan, and Ron Bolton, Washington State University, Pullman
    • Remediation of Stratified Soil Acidity Through Surface Application of Lime in No-till Cropping Systems
      Carol McFarland,1 David R. Huggins,2 Kurt L. Schroeder,3 J. Joey Blackburn,1 L. Carpenter-Boggs,1 Rich Koenig,1 and Timothy C. Paulitz;2  1Washington State University, Pullman; 2USDA-ARS, Pullman and 3University of Idaho, Moscow, ID
    • Nutrient and Soil pH Management Strategies:
      • Nutrient Management of Winter Canola – Don Wysocki, Oregon State University
      • Nutrient Management of Spring Canola – Markus Braaten, Agri-Trend, Montana
      • Soil Health, Testing and Management – Paul Carter, WSU Extension Columbia Co.
  • 2014 WSU Oilseed and PNDSA Direct Seed Conference
    • Stratified Soil pH Identification Project
      Paul G. Carter, WSU Extension, Dayton, WA and Terry Bruegman, Columbia Conservation District, Dayton, WA
    • Canola and Soil pH
      Jason Imes and Gudrun Mahrt; Columbia River Carbonates, Woodland, WA
    • Considering Aluminum Toxicity When Diagnosing Bare Patches and Stunted Plants in the Field
      Carol McFarland1, Joey Blackburn1, Dave Huggins2, Kurt Schroeder3, and Tim Paulitz2; 1Dept. Crop and Soil Sciences, WSU; 2USDA-ARS, Pullman, WA; 3Dept. of Plant, Soil and Ent. Sci., Univ. of Idaho
    • Tillage and Cropping Intensity Influence on Important Soil-Health Indictors and Processes
      Jason Morrow1 and Dave Huggins2; 1Dept. of Crop and Soil Sciences, WSU; 2USDA-ARS Soil Scientist, Pullman, WA
    • How Can I Tell if My Soil is Healthy?
      Marlon Winger – USDA-NRCS, Boise, ID
  • 2013 Oilseed Production and Marketing Conference
    • Oilseed Root Characteristics: Implications for Water and Nutrient Management
      W. Pan, A. Hammac, T. McClellan, I. Madsen, L. Graves, K. Sowers, L. Young, R. Bolton, Washington State University
  • 2012 Oilseed Crop Production Workshop
    • Canola Nutrient Management
      Rich Koenig, WSU
  • 2011 Oilseed Crop Production Workshop
    • Re-evaluating Fertility Recommendations for Canola: The Nitrogen Catch and Release Crop
      Ashley Hammac, Rich Koenig and Bill Pan; Washington State University

  • Pan, W. 2015. The Roots of Soil Fertility. Invited Leo M. Walsh Soil Fertility Distinguished Lectureship, recorded at ASA-SSSA-CSSA meetings, Minneapolis, MN. December 16, 2015.
  • Madsen, I.J., M.E. Reese, T.L. Beard, T.M. Maaz, L.E. Port, M.L. Nunez, J.C. Huettenmoser, and W.L. Pan. 2015. Subsoil Accessibility and Nutrient Availability in Three Rainfall Zones in the Inland Pacific Northwest. Climate Change and Cereal Production in Semi-Arid Regions of the World. REACCH International Conference. Minneapolis, MN.
  • Madsen I., W. Pan, and R. Bolton. Detecting Moisture Change in Fertilizer Microsites through Soil Color-Moisture Calibrations. Soil Science Society of America Annual Meeting. November 16-18. Minneapolis, MN. 2015. ASA/SSSA/CSSA Online Program; SSSA Division: Nutrient Management & Soil & Plant Analysis. ASA/SSSA/CSSA Annual Conference; 11/15-18/2015; Minneapolis MN.
  • Koenig, R. 2012. Oilseed Fertility Management. It’s Not Your Father’s Wheat. Oral presentation in Pacific Northwest Oilseed Crop Adaptation session. Northwest Bioenergy Research Symposium. Seattle, WA. Nov. 13, 2012.
  • Pan, W., A. Hammac, T. McClellan, I. Madsen, L. Graves, K. Sowers, and L. Young. 2012. Oilseed Root Characteristics: Implications for Water and Nutrient Management. Poster presentation at Northwest Bioenergy Research Symposium. Seattle, WA. Nov. 13, 2012.

Nitrogen in Canola

Nitrogen (N) is frequently one of the most limiting nutrients in canola production systems in the Washington. Nitrogen is taken up by plants as either ammonium (NH4+) and nitrate (NO3–). Ammonium is generally considered immobile and does not leach deep into the soil profile whereas nitrate is generally considered mobile and can leach with in the soil profile. Due to the variation in mobility ammonium samples are only taken in the surface soils whereas nitrate samples are taken to a depth of 4-6’. Nitrogen deficiencies show up as yellowing on the oldest leaves. While some level of nitrogen correction can be made during the growing season it is preferable to develop a strong nutrient management plan prior to the growing season.

Phosphorus in Canola

Phosphorus (P) is a structural component of DNA, RNA, and cell membranes in living organisms. Phosphorous has limited mobility in the soil and in acidic or alkaline soils, P can become strongly absorbed to soil particles thereby reducing the availability of P to the plant roots. Plants have developed a variety of strategies to improve P availability. Phosphorous may be a limiting nutrient in canola production. However, in the majority of P research studies conducted in Washington it was found that P replacement strategies common in wheat production were adequate for supplying canola P needs. Anecdotal evidence indicates that soil test P can be increased through the frequent use of canola in rotation.

Sulfur in Canola

Sulfur–like N–is an essential element for plant growth and frequently a limiting factor in agricultural systems. Sulfur is taken up by plants as the anion sulfate (SO4–). In wet years, SO4– may leach deep into the soil profile. When developing a canola nutrient management plan, soil samples for SO4– should be taken to a depth of 3-5’. In the canola plant S is an immobile nutrient which means deficiency symptoms will most likely show up on new leaves. Frequently, S deficiency symptoms do not show up until the plant has initiated bolting. S deficiency is characterized by cupped and purple leaves on the stem.