Managing other Nutrients

Table of contents

    Management of Nutrients other than N, P, K, S

    Important tips for best management

    • The best return on fertilizer investment for canola comes from N, P and S. For nutrients other than these, namely the nutrients described in this chapter, deficiencies that cause noticeable yield reduction can happen but are rare.
    • In situations where deficiency of these secondary nutrients or micronutrients is suspected, apply fertilizer to a small affected area and mark it clearly. Visual observations combined with final yield measurements from the treated and untreated areas should help determine if a measurable response occurred, and can help determine your approach to that micronutrient in future years.
    Table 3. Plant Tissue Analysis Interpretative Criteria for Canola (whole above ground plant at flowering)
    NutrientSufficiency Level
    Nitrogen (N) % > 2.4
    Phosphorus (P) % > 0.24
    Potassium (K) % > 1.4
    Sulphur (S) % > 0.24
    Calcium (Ca) % > 0.49
    Magnesium (Mg) % > 0.19
    Zinc (Zn) ppm > 14
    Copper (Cu) ppm > 2.6
    Iron (Fe) ppm > 19
    Manganese (Mn) ppm > 14
    Boron (B) ppm > 29
    Molybdenum (Mo) ppm > 0.02


    Calcium supply for canola

    Canola has high demand for calcium (Ca). Canola needs Ca at about double the level of sulphur and phosphorus, but deficiencies in western Canada are rare due to ample soil reserves. Also, only 10% of plant Ca ends up in canola seed. The rest is returned to the field in crop biomass. This is why Ca, while needed in large amounts, is considered a secondary nutrient.

    Response of canola to applied Ca

    Western Canada has relatively new soils, and Ca levels are still very high. For example, of the 863 canola tissue samples ALS labs tested for Ca deficiency in 2012, only one was below 0.4%. Ca deficiency tends to be more common in older more weathered soils that have been farmed for much longer and are exposed (no snow cover) more months of the year.

    Odds of getting a canola response to applications

    Low.Ca fertilization is not necessary for canola production on the majority of soils in western Canada.

    The table below shows exchangeable and extractable Ca reserves in Western Canadian soils. These levels are considered well above deficiency levels, but in fact there is no good criteria to determine the connection between soil Ca levels and deficiency.

    Soil type1N NH4OAc extractable Ca, mg kg-1
    Non-calcareous 3200 ± 1051
    Calcareous 6560 ± 3235
    All soils 4050 ± 5263


    In western Canada, responses to Ca have been reported in the Peace River Region and East Central Alberta and are associated with soils of high sodium (Na) content.

    Situations that produce the greatest chance of a response

    Calcium deficiency is possible in:

    • Strongly acidic soils.
    • Strongly alkaline non-saline soils. These soils contain high exchangeable sodium levels and have a high pH.
    • Sandy soils with very low organic matter levels, low CEC and high oxide content.
    • Soils from parent materials high in serpentine, i.e., contain disproportionately high magnesium content.
    • Saturated soils can cause temporary Ca deficiency, but in this case Ca fertilizer will not help. Excess soil moisture can make it difficult for canola plants to take up nutrients, and in some cases, calcium deficiencies showed up more vividly than other deficiencies. This is likely due to crop growth stage and the timing or duration of the flooding. Cell extension requires Ca. Rapidly growing parts are, therefore, most affected by Ca deficiency. In this case, the best course of action would be to wait until the soil dries up and the crop starts growing again. Symptoms can correct themselves.


    Identifying deficiencies -symptoms and tests

    Calcium deficiencies look like:

    • ”Ribbon stem.” The stem goes flat and flops over, typically just below the growing point (bud or flower cluster) at the top of stems and branches.
    • Accelerated maturity. The plant will set seed quickly, sometimes locking in low yield.
    • Yellowing, browning and necrosis (tissue dies) in patches in the middle of leaves. This is actually a unique symptom of calcium deficiency.
    • Dark spots on pods which turn brown and necrotic.


    A soil test can provide soil Ca levels, but no soil criteria have been established to show at what level soils are considered Ca deficient for canola.

    A tissue test may show plants are deficient in calcium, but calcium may be in the soil at adequate rates, it’s just the plant can’t access it because of saturated soils. A rescue application of these products will not help in this case. Plants often recover after soils dry out.

    Cation exchange capacity (CEC) is a measure of a soil’s ability to hold on to key positively charged nutrients, such as calcium, magnesium and potassium, and keep them close for when the crop needs them. In western Canada, soils with high clay and high organic matter tend to have a high CEC, so these soils are more likely to have an adequate supply of these nutrients on hand. A CEC of 1 milligram of hydrogen equivalent (meq) per 100 grams of soil is very low. CEC is ideally between 10 and 30 meq/100g. To calculate CEC on a soil, take the soil’s percentage of clay and multiply by 0.5, then take the percent organic matter and multiply by 2. Add these two numbers to get CEC.

    Fertilizer sources and methods of application

    Calcium nitrate or calcium sulphateare the most common Ca fertilizer products.

    Limestone. Calcium carbonate (CaCO3) or Calcium oxide (CaO) — “lime” — is usedto raise the pH on acid soils. It can also have the added benefit of increasing soil calcium content, but is not generally recommended as a calcium treatment in soils that don’t need pH adjustment.

    Foliar, dribble band.Liquid formulations are on the market from various sources and in various blends, often including a mix of micro- and macronutrients. This is a better application method than seed applied for a macronutrient such as Ca as it allows for rates sufficient to correct deficiencies.

    Seed treatment: Research in Alberta and by the Canola Council of Canada in 2000 using seed treatment with Ca5S did not find a response in canola at nine locations.

    Magnesium supply for canola

    Of the macronutrients, magnesium is absorbed in the least amount. Magnesium deficiencies are rare on the Prairies, similar to Ca.

    Response of canola to applied Mg

    Little information exists on Mg requirements of canola. There are no known cases of canola response to Mg fertilizer in Canada or Europe. Therefore, no reliable soil or canola tissue test criteria exist. However, Mg deficiency appears unlikely in slightly acidic to neutral soils that do not have excessive amounts of root zone Ca, K or NH4+.

    Odds of getting a canola response to applications

    Very low,as per the lack of documented responses discussed in previous section.

    Situations that produce the greatest chance of a response

    If magnesium deficiency were to occur, it is more likely in soils with:

    • higher pH and free lime. In these soils, Ca+2 will dominate the exchange sites, possibly inducing Mg deficiency.
    • low pH. At low pH, H+, Al+3, and manganese (Mn+2) under flooded conditions, will dominate the exchange sites, inducing Mg (and Ca) deficiency.
    • high K+ or NH4+ levels in the root zone due to fertilization. Mg deficiency in this situation would likely be short term.

    Identifying deficiencies - symptoms and tests

    Actual photos of symptoms on canola are lacking due to the rarity of actual in field deficiencies. However general symptom descriptions suggest interveinal or blotchy chlorosis or necrosis on older leaves as most likely.

    Fertilizer sources and methods of application

    Magnesium sulphateis the most common Mg fertilizer source.

    Potassium magnesium sulphate.Sold by Mosaic as K-Mag, this dry fertilizer product contains 21-22% potassium, 10-11% magnesium and 21-22% sulphur.

    Tissue test levels for micronutrients in canola: at flowering
    MicronutrientLowMarginalSufficient
    Boron <20 20-30 30
    Copper <1.7 1.7-2.7 2.7
    Iron <15 15-20 20
    Manganese <10 10-15 15
    Zinc <12 12-15 15

    Source: Alberta Agriculture and Rural Development and Manitoba Provincial Soil Testing Laboratory


    BORON

    Boron supply for canola

    Boron is one of the essential micronutrients for plant production and canola has higher boron (B) requirements than wheat or barley. Of the known micronutrient deficiencies, boron deficiency is the most widespread globally.However, B deficiency is rare in western Canada, and even when deficiencies are found, canola response to B fertilizer is limited.

    Response of canola to applied B

    A 40-site trial from Western Canada found that canola did not respond to B application, even on soils containing <0.15 mg kg (ppm) of boron, which is considered low. Research by AAFC at Melfort, Saskatchewan did not find a B response on four soils testing low in B, and one soil was similar to the responsive site in a previous study. Two years of foliar and soil applied B trials on a sandy Black soil in central Alberta testing very low in B did not find any yield response with either B. rapa or B. napus canola. The Battle River Research Group did not find a B response after 2 years of trials in central Alberta. Research in Washington and Idaho on three soils testing low in B did not find a canola yield response to B fertilizer. Irrigated canola research conducted by Alberta Agriculture Food and Rural Development near Lethbridge did not find a yield response to micronutrients, including boron, over six site-years.

    However, there have been cases where B fertilizer did show a response under controlled conditions. AAFC pot studies with B. rapa rapeseed on Alberta Gray Wooded soils showed that B deficiency symptoms and poor seed set were alleviated with added B. Under field conditions, the Canola Council of Canada recorded a significant yield response to B at its Crop Production Centre site near St. Claude, Manitoba in 2000.

    Odds of getting a canola response to applications

    Low for general treatment, low-moderate for in season stress response.

    Boron fertilization of canola has not consistently improved seed yield, kernel weight, protein or oil content. Where boron deficiency does occur in western Canada, it probably is in small field patches. A 1990s study in northeastern Saskatchewan, an area where a reduction in canola yields was thought to have been due to B deficiency, found no benefit from B fertilizer — either seed row or foliar applied. One of the study’s conclusions was that even after conducting soil and plant tissue analyses it is still difficult to predict a profitable yield increase from B fertilization.

    A northern Quebec study of boron on canola did find an economic response from foliar applications of 1 kg/ha (1 lb./ac.) of B in fields where boron deficiency had previously been reported in barley.

    Boron as a stress treatment. Foliar boron applied at flowering has been tested on canola in Ontario as a way to prevent blossom blast during summer heat waves. Four years of grower field studies from 2008-11 found inconclusive results. In the trials, foliar boron applied at flowering improved yields marginally by 3% on average, but rarely resulted in an increase in return.

    Situations that produce the greatest chance of a response

    In the Ontario research noted in the previous paragraph, the greatest yield improvement occurred in 2010, a year with higher temperatures at flowering than in 2008 and 2009 when temperatures were cooler than normal. In 2011 conditions were cooler than 2010 but extremely dry.

    Boron deficiency is more likely to occur in:

    • Sandy soils with low organic matter. Boron tends to leach in these soils. In general, sandy soils and soils with less than 1% organic matter have lower micronutrient availability. Grey Luvisols have also shown a higher likelihood of boron deficiency.
    • High pH soils (8.0 or higher). Generally, B becomes less available as pH increases above 6.3 to 6.5. At higher pH, the borate anion is likely adsorbed to clay and organic particles.
    • Drought. Under drought conditions, B deficiency can occur due to reduced mass flow to roots as well as polymerization of boric acid. B uptake rates increase as the level in the soil water increases. B moves through the soil with mass flow, not diffusion, so a rain event can alleviate most boron deficiencies. Also, soil organic matter is the primary source of B in western Canadian soils and under drought, mineralization (release of B from soil organic matter) is slowed.
    • Saturated fields. Under high rainfall conditions B can be leached in sandy textured soils.
    • Fields with high levels of calcium and potassium. These antagonisms have been shown to increase B deficiency symptoms, but they are not well understood.


    Identifying deficiencies - symptoms and tests

    Canola is more sensitive to low soil boron during the reproductive stage than the vegetative stage, so if deficiency symptoms show up at the vegetative stage this is a sign of potential serious deficiency, which could have an effect on yield.

    Boron deficiency symptoms in canola first appear in new growth due to the intermediate mobility. Symptoms range from:

    • New leaves are stunted and may roll up along the length of the leaves around the mid vein. Leaves may look generally deformed and be rough skinned leaves with torn margins
    • Interveinal chlorosis. Veins are green but the rest of the leaf is light green. Chlorosis can look like yellow to brown spots in the interveinal areas of leaves
    • Red to brown-purple coloured new leaves
    • Early leaf drop
    • Shortened stems
    • Cell walls are dramatically affected by B deficiency. This shows up as cracked, hollow or corky stems. The cell wall diameter and proportion of plant dry weight increases under B deficiency. Most plant B is complexed with organic compounds in the cell walls, apparently serving a nonspecific structural role.
    • Long and unproductive flowering period, flower sterility and poor pod set. Boron is involved in pollen tube fertilization, and with boron deficiency, pods may not form. The plant keeps flowering and flowering producing new bud clusters from leaf axils, trying to get fertilization and pod set to occur.
    • Short, stunted root hairs and poor rooting. One of the first plant responses to induced B deficiency is decreased root elongation, however, there is a lack of understanding how this occurs.

    To identify a boron deficiency:

    • Ensure that poor crop growth is not the result of a macronutrient deficiency (visual symptoms can easily be confused with S deficiency symptoms), drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    • Check around to see whether boron deficiency has been identified in a particular crop or soil type in the area.
    • Examine the affected crop for symptoms described above.
    • Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients. Unfortunately, even with a soil test result that shows deficiency, there is not a consistent indicator to predict profitable canola yield response to B fertilizer. The problem with all boron soil tests is that alone they are a weak indicator of boron availability. Most boron supplied to the crop comes from the breakdown of organic matter, a soil test has to consider soil OM percentage, and given that boron is very mobile in the soil, you really need soil texture as well. Boron, like nitrogen and sulphur, is subject to leaching.
    • Send plant tissue samples from both the affected and unaffected areas for complete analysis, including micronutrient levels. Plant analysis at early flowering may help to identify B deficiency. The youngest open leaf is shown to be the most reliable tissue to identify B deficiency in Brassica napus, but be sure to follow the labs requirement for plant parts submitted, how many to submit, and how to choose a proper sample.
    • If all indications point to a micronutrient deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.


    Even after observing B deficiency symptoms and conducting soil and plant tissue analyses, prediction of a profitable yield response is difficult. Therefore, in situations of suspected deficiency, apply B fertilizer to a small affected area of the field in a carefully marked test strip. Visual observations combined with yield measurements from the treated and untreated areas should help determine if a measurable response occurred. If a positive response is measured, B fertilizer could be applied in future canola crops on these areas.

    Fertilizer sources and methods of application

    Sodium borate.The most common boron product is sodium borate, broadcast and incorporated in the spring at rates of 0.5–1.5 lb./ac. or foliar applied at 0.3 to 0.5 lb./ac.

    • Broadcast-incorporated.This is the safest method, as boron can be toxic to canola seedlings.Application rates should not exceed 1.7 kg/ha (1.5 lb./ac.) on soils with a pH less than 6.5 to avoid boron toxicity problems.
    • Banding. Do not place more than 1.7 kg/ha (1.5 lb./ac.) in close proximity to the seed row.
    • Foliar B fertilization appears to be effective up to the early flowering stage. Ensure foliar applications do not exceed 0.3 kg/ha (0.3 lb./ac.) to avoid toxicity problems. For all applications, extreme care must be taken to apply the correct amount uniformly to avoid toxicity.
    • Seed placement is not recommended as concentrated boron can be toxic to seedlings. Rates of sodium borate that exceed 1.0 lb./ac. in the seed row can kill canola seedlings.


    Clubroot bonus, maybe: A controlled study has shown that boron can help reduce clubroot severity. Several field trials are being assessed to see whether this has a practical application for growers. Initial expectation is that rates of boron needed to show a benefit for clubroot management may be toxic for canola plants.

    Copper supply for canola

    Response of canola to applied Cu

    Black, transitional Gray-Black and Dark Brown soils may be copper (Cu) deficient for cereal production. Canola is not as sensitive as cereals to Cu shortages, but canola can still show a response to copper application in deficient soils.

    Odds of getting a canola response to applications

    Low unless soil tests show extremely low copper levels — below 0.2 mg/kg (ppm). On those soils, cereals should be showing clear benefits from Cu applications. Canola has shown to be more tolerant of soil Cu deficiencies than wheat, barley, oats and flax. A compilation of research data from Saskatchewan and Alberta on mineral soil suggests that 0.30 mg/kg (ppm) diethylenetriaminepentaacetate (DTPA) extractable Cu may be the critical level for canola. Since the critical Cu level is much lower for canola than cereals, Cu fertilization programs for deficient soils should focus on application to the cereal rotation phases.

    Situations that produce the greatest chance of a response

    Copper deficiency is more likely to occur in:

    • Sandier soils with low organic matter. Copper oxide and organic fractions increase with the clay content, which explains why Cu deficiency is more likely on sandier textures.
    • Organic or “peat” soils. Soils that have very high levels of organic matter (greater than 30% organic matter to a depth of 30 cm) often have low micronutrient availability.
    • Peat soils with a manganese:copper ratio (DTPA extractable) greater than 15.
    • Molybdenum also may antagonize Cu. However, the Mo antagonism is in turn affected by S levels. Sulphur additions were found to lower Mo contents in canola plants, reducing Mo antagonism with Cu, and Cu deficiency was alleviated without adding Cu fertilizer.


    Identifying deficiencies - symptoms and tests

    • Canola does not display strong Cu deficiency symptoms. Pot experiments with extreme Cu deficiency have reported canola symptoms of:
    • interveinal chlorosis shortly after emergence
    • larger than normal leaves
    • wilting leaves
    • delayed flowering with a shortened flowering stem
    • Due to copper’s role in photosynthesis, deficiency leads to low carbohydrate levels, at least during the vegetative stage. The low carbohydrate content in Cu deficient plants contributes to impaired pollen formation and fertilization. The reduced lignification in Cu deficient plants also affects pollen fertility since lignification of anthers is needed to release pollen.
    • Despite the intermediate mobility of Cu, deficiency symptoms in sensitive crops during the vegetative stage first appear in new growth.

    To diagnose a copper deficiency:

    • Ensure that poor crop growth is not the result of a macronutrient deficiency, drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    • Find out if a micronutrient deficiency has been identified before in a particular crop or soil type in the area. If copper fertilizer provides an economic benefit for cereals in the area, then it is more likely to also help canola in the area. If cereals are not deficient, canola will not be either.
    • Examine the affected crop for specific micronutrient deficiency symptoms.
    • Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients. Soil test methods (DTPA extraction) show that Cu is highly variable across fields. This means that larger numbers of soil samples are needed to obtain a precise estimate of the true soil average.
    • Send plant tissue samples from both the affected and unaffected areas for complete analysis that includes tests for micronutrient levels.
    • If all indications point to a copper deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.


    Fertilizer sources and methods of application

    Copper sulphate or copper oxide: Broadcast and incorporated rates of 3.4 to 8 kg/ha (3-7 lb./ac.) of copper in the form of copper sulphate is recommended for deficient mineral soils. Copper oxide at similar rates is also effective, but not in the year of application. Increase broadcast and incorporated rates of copper fertilizer to 11-17 kg/ha (10-15 lb./ac.) when applied on peat soils, but be cognizant of the Mn:Cu interaction that can result in Mn deficiency. Soil application rates should be effective for up to 10 years.

    Chelated forms of copper can be effective in the year of application,  but there is no residual benefit (see below for more on chelates). Chelated copper can be broadcast and incorporated at 0.6 kg/ha (0.5 lb./ac.) of Cu, seed placed at 0.3-0.6 kg/ha (0.25-0.5 lb./ac.) or foliar applied at 0.2-0.3 kg/ha (0.2-0.25 lb./ac.)

    Foliar application on mineral and organic soils can be an effective rescue, unless deficiency is severe. Foliar rates of 0.1-0.3 kg/ha (0.1-0.3 lb./ac.) are recommended.

    Chelated micronutrient fertilizers.Chelates are negatively charged organic molecules that create a protective bond with positively charged micronutrients. This prevents micronutrients from binding with soil particles and becoming insoluble and unavailable to the plant. Iron, zinc, copper, manganese, calcium and magnesium can be chelated. Chelates are especially useful for micronutrients applied to alkaline soils. High pH soils are more likely to have ions that will bind with micronutrients to become insoluble substances. Plant roots take up the chelated nutrient, and the micronutrient is released inside the plant. Chelated micronutrient fertilizers are more expensive, but are more efficiently taken up by the plant, hence the lower rates.

    Iron supply for canola

    Response of canola to applied Fe

    Western Canadian soils developed from parent materials rich in iron (Fe). Therefore, there have been no reports of Fe deficiency in field crops or responses to Fe fertilizer on the Prairies. Also, there has been no work to calibrate soil test values for Fe on the Prairies.

    Odds of getting a canola response to applications

    Low.

    Situations that produce the greatest chance of a response

    Presence of lime in the soil may induce iron chlorosis, which is common in some Northern Great Plains soils. Iron chlorosis is common in gardens grown on calcareous soils and with Fe sensitive crops, such as strawberries. Fe chlorosis is also observed with some broadleaf shrubs and trees.

    Identifying deficiencies - symptoms and tests

    Iron is needed for chlorophyll synthesis, and low chlorophyll contents of young leaves (interveinal “chlorosis” or yellowing) is the most obvious visible symptom of Fe deficiency. However, yellowing of young leaves can have many causes, and iron deficiency would not be a likely cause.

    1. Ensure that poor crop growth is not the result of a macronutrient deficiency, drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    2. Find out if a micronutrient deficiency has been identified before in a particular crop or soil type in the area.
    3. Examine the affected crop for specific micronutrient deficiency symptoms.
    4. Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients.
    5. Send plant tissue samples from both the affected and unaffected areas for complete analysis that includes tests for micronutrient levels.
    6. If all indications point to a micronutrient deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.

    Fertilizer sources and methods of application

    Iron sulphate. Foliar application of iron sulphate on garden vegetables, fruits and shrubs is an effective means of correcting Fe deficiencies. Consult manufacturer label for instructions for use on canola.

    Manganese supply for canola

    Response of canola to applied Mn

    Manganese is a metallic micronutrient that is occasionally deficient in western Canadian organic, high pH soils. Although oats can be affected by Mn deficiency in cold organic soils (gray speck of oats disease), there have been no documented problems with canola.

    Odds of getting a canola response to applications

    Low, and lower for canola than for other crops. Rhizosphere acidification by canola roots likely increases Mn availability and makes this crop relatively tolerant of low soil Mn.

    Situations that produce the greatest chance of a response

    Manganese deficiency is more likely to occur in:

    • Soils with higher pH. Manganese availability decreases when pH increases above 6.2 in many soils.
    • Soils that have very high levels of organic matter, especially when cool. Generally, soils with greater than 30% organic matter to a depth of 30 cm have low micronutrient availability.
    • Mn:Cu ratios above 15 in the plant may lead to Cu deficiency while ratios below 1 may lead to Mn deficiency.


    Mn toxicity — too much available Mn in the soil — can also occur in canola. It was documented on a field of canola near Lac La Biche, Alberta, in 2010. Manganese toxicity causes chlorosis of leaf margins and cupping of leaves in canola.

    Identifying deficiencies - symptoms and tests

    Mn deficiency is not well documented in canola but could be similar to Mn deficiency in other crops, characterized by interveinal chlorosis while veins stay green.

    To identify deficiency:

    • Ensure that poor crop growth is not the result of a macronutrient deficiency, drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    • Find out if a micronutrient deficiency has been identified before in a particular crop or soil type in the area.
    • Examine the affected crop for specific micronutrient deficiency symptoms.
    • Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients.
    • Send plant tissue samples from both the affected and unaffected areas for complete analysis that includes tests for micronutrient levels.


    If all indications point to a micronutrient deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.

    Fertilizer sources and methods of application

    Manganese sulphate. Could be broadcast-incorporated in the spring at 50-80 lb./ac. of Mn, although this is not usually economical. It can be seed-placed at 4-20 lb./ac.

    Chelated manganese.Foliar applied at 0.5-1 lb./ac. of Mn.

    Potash (KCl) has been shown to enhance Mn uptake by several crops.

    Molybdenum supply for canola

    Response of canola to applied Mo

    Molybdenum is needed in extremely low amounts, yet all Brassica species appear to be sensitive to low Mo supply. Molybdenum functions are closely related to N metabolism and N fixation.

    Odds of getting a canola response to applications

    Deficiencies in canola have not been documented in western Canada.

    Situations that produce the greatest chance of a response

    Deficiency may be more likely to occur in acid mineral soils with a large content of reactive iron oxide hydrates. Some interaction occurs between Mo uptake and levels of P and S. Plant Mo uptake is usually enhanced by soluble P and decreased by sulphate. MoO4-2 and SO4-2 compete strongly for root uptake.

    Molybdenum deficiency tends to occur more often in acid (low pH) soils. This is an exception. Other micronutrients become less available as pH rises.

    Identifying deficiencies - symptoms and tests

    Specific information on canola is limited, but brassicas deficient in Mo show cupping of leaf margins of younger leaves, interveinal chlorosis and, in later stages, a twisting of leaves around the central mid-rib.

    To identify a Mo deficiency:

    • Ensure that poor crop growth is not the result of a macronutrient deficiency, drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    • Find out if a micronutrient deficiency has been identified before in a particular crop or soil type in the area.
    • Examine the affected crop for specific micronutrient deficiency symptoms.
    • Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients.
    • Send plant tissue samples from both the affected and unaffected areas for complete analysis that includes tests for micronutrient levels.


    If all indications point to a micronutrient deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.

    Fertilizer sources and methods of application

    Sodium or ammonium molybdate.Soil or foliar. Given that Mo is needed in such trace amounts, a seed treatment may also work.

    Liming to raise soil pH can help to make more soil Mo available to crops.

    Mo is unique among the micronutrients since there is a wide range between deficiency and toxicity.

    ZINC

    Zinc supply for canola

    Response of canola to applied Zn

    In western Canada, sporadic Zn deficiencies have been identified in fields of alfalfa, flax and beans, but not canola.

    Odds of getting a canola response to applications

    Low.

    Situations that produce the greatest chance of a response

    Zinc deficiency is more likely to occur where:

    • pH of soil is high. Zinc availability increases as soil pH decreases (becomes more acidic). Deficiencies are more likely on high pH, calcareous soils due to Zn adsorption to lime particles.
    •  High rates of P have been applied. Application of P fertilizer may increase Zn deficiency. High P levels can induce Zn deficiency by inhibiting Zn translocation within the plant rather than affecting root uptake.

     

    Identifying deficiencies - symptoms and tests

    Zinc deficiency symptoms range from:

    • Leaf chlorosis and inhibited stem elongation. Membrane stability relies on Zn, so these symptoms probably arise from membrane breakdown.
    • Purpling on new emerging leaves
    • Brown spots on cotyledons
    • Interveinal chlorosis
    • Cupping of leaves.


    To identify a zinc deficiency:

    • Ensure that poor crop growth is not the result of a macronutrient deficiency, drought, salinity, disease or insect problem, herbicide injury or some physiological problem.
    • Find out if a micronutrient deficiency has been identified before in a particular crop or soil type in the area.
    • Examine the affected crop for specific micronutrient deficiency symptoms.
    • Take separate soil samples from both the affected and unaffected areas for complete analysis, including micronutrients.
    • Send plant tissue samples from both the affected and unaffected areas for complete analysis that includes tests for micronutrient levels.
    • If all indications point to a micronutrient deficiency, apply the micronutrient to a specific, clearly marked out affected area of land to observe results in subsequent seasons.


    Fertilizer sources and methods of application

    Zinc sulphate.Can be broadcast and incorporated in spring or fall at 3.5-5 lb. Zn/ac.

    Zinc oxysulphate.Can be broadcast and incorporated in fall at 5-10 lb. Zn/ac.

    Chelated zinc.Can be foliar applied at 0.3-0.4 lb. Zn/ac., or broadcast incorporated at 1 lb.Zn/ac.

    References

    From Dianne Kemppainen with ALS Environmental in Saskatoon, November 2012.

    Karamanos, R.E. and Flore, N.A..  2001.  Soil adsorption of and plant response to applied calcium.  Proc. Soils and Crops 2001, February 22-23, University of Saskatchewan, Saskatoon, Saskatchewan. Data came from Enviro-Test Laboratories.

    Karamanos, R.E., personal communication. He says critical levels can be and, very much are, cultivar (variety) dependent.

    Haby, V.A., Russelle, M.P. and Skogley, E.O. 1990. Testing soils for potassium, calcium and magnesium. p 181-227. In R.L. Westerman (ed.) Soil testing and plant analysis. SSSA Book Series 3. SSSA, Madison, WI.

    Karamanos, R.E. and Flore, N.A., 2001, “Soil absorption of and plant response to applied Calcium,” Proc. Soil & Crops. February 22-23, University of Saskatchewan, Saskatoon, Saskatchewan.

    Karamanos, R.E., in a personal communication, said “The only magnesium deficiency that Les Henry and I ever documented in Saskatchewan at least was on a field near Choiceland that was extremely sandy and derived from parent material that is poor in Mg bearing minerals. The cure was dolomite.” Dolomite is calcium magnesium carbonate, which contains 2-13% Mg.

    Gupta, Umesh C., Chapter 8 Boron, “Handbook of Plant Nutrition.” 2006, Editors Allen V. Barker, David J. Pilbeam

    Karamanos, R. E., Goh, T. B. and Stonehouse, T. A. 2003. Canola response to boron in Canadian prairie soils. Can. J. Plant Sci. 83: 249–259. This study found no response to boron fertilizer, even on soils with less than 15 mg/kg hot-water extractable B and with control canola yields of up to 63 bu./ac. This suggests that responses to B are rare on Prairie soils and in any event hot water extractable B is not an appropriate index to identify B deficiencies.

    S.S. Malhi, K. Kutcher, A. Johnston and D. Leach, “Feasibility of boron fertilization on canola in the Saskatchewan parkland,” presented to Soils and Crops Symposium 2000, Saskatoon, Saskatchewan. The study made the following valuable agronomic recommendation: “Some producers apply B fertilizer to canola without knowing if B application increases seed yield of canola. In order to save money and optimize the use of B fertilizer, the following are suggestions to the canola producers: (a) Apply B fertilizer in test strips and determine if there is any increase of seed yield, and then consider B fertilization of whole fields on a regular basis. (b) If it is already planned to use B fertilizer on canola, then leave some canola strips without B fertilizer in the field and compare the seed yields with and without B fertilizer.”

    Pageau, Denis, Lafond, Jean and Tremblay, Gaëtan F., “The effects of boron on the productivity of canola,” presented at the 10th International Rapeseed Congress, Canberra, Australia 1999. The study found that when boron leaf concentration at flowering was 7-15 mg/kg (ppm), a foliar B fertilizer application significantly increased grain yield. At the site where boron leaf concentration was above 30 mg/kg, plants showed no B deficiency symptoms. The study conclusion: “Boron fertilization can increase canola grain yield and oil content only when plants are boron deficient. Boron concentration in leaves at flowering for B deficient plants was generally lower than 15 mg/kg of boron. In the present experiment, an application of 1 kg B ha -1 was sufficient to correct B deficiency.”

    Can1-2011 Evaluation of Boron in Spring Canola Production, Crop Advances, Field Crop Reports, Volume 8 — February 2, 2012. Ontario Ministry of Agriculture, Food and Rural Affairs in partnership with Ontario Soil and Crop Improvement Association and other Agricultural Organizations and Businesses.

    Can1-2011 Evaluation of Boron in Spring Canola Production, Crop Advances, Field Crop Reports, Volume 8 — February 2, 2012. Ontario Ministry of Agriculture, Food and Rural Affairs in partnership with Ontario Soil and Crop Improvement Association and other Agricultural Organizations and Businesses. This summary states: “This would support preliminary research conducted by Dr. Hugh Earl, University of Guelph with foliar boron applied at flowering. In Dr. Earl’s growth room studies, boron applied to canola that was under heat stress, improved retention of pods on the main raceme. The results from these field trials (73 % wins) indicates that where growers intend to apply a fungicide at flowering, the application of boron at the same time is relatively inexpensive (cost of boron is approximately $5/ac @ 0.3 lb/ac B) and would likely result in breakeven or a small increase in return.”

    Karamanos, R.E., personal communication.

    Nuttall, W.F., Ukrainetz, Hl, Stewart, J.W.B, and Spurr, D.T., 1987, “The effect of nitrogen, sulphur and boron on yield and quality of rapeseed,” Can. J. Soil Sci. 67: 545-559

    A. Asad, F. P. C. Blamey and D. G. Edwards, 2002, Dry matter production and boron concentrations of vegetative and reproductive tissues of canola and sunflower plants grown in nutrient solutionPlant and Soil, Volume 243, Number 2 , p. 243-252

    Ross McKenzie, 1992, Micronutrient Requirements of Crops, Alberta Agriculture and Rural Development, Agdex 531-1

    Huang, L, Ye, Z, and Bell, R.W. “The importance of sampling immature leaves for the diagnosis of boron deficiency in oilseed rape,” Plant and Soil 1996, Volume 183, Issue 2, pp 187-198

    Karamanos, R.E. provides the following boron recommendations for Canadian Prairie soils, which he developed from Westco Fertilizer’s (now Viterra) database for the AgroMax series of tip booklets.

      Soil testProbability of precipitation
    Texturea Organic Bb range 75% 50% 25% 10%
      matter ppm   cereal oilseed cereal oilseed cereal oilseed
     lb B/acre
    S, LS, SL <2% 0 - 0.25 0 0.5 1.5 0.5 1.5 0.5 1.5
      <2% >0.25 0 0 0 0 0 0 0
      >2% 0 - 0.25 0 0 0 0.5 1.5 0.5 1.5
      >2% >0.25 0 0 0 0 0 0 0
    L <1% 0 - 0.25 0 0 0 0.5 1.5 0.5 1.5
      <1% >0.25 0 0 0 0 0 0 0
      >1% 0 - 0.25 0 0 0 0 0 0.5 1.5
      >1% >0.25 0 0 0 0 0 0 0
    CL All 0 - 0.25 0 0 0 0 0 0.5 1.5
      All >0.25 0 0 0 0 0 0 0
    C <1% 0 - 0.25 0 0 0 0 0 0.5 1.5
      Other All 0 0 0 0 0 0 0

    a S=sand, LS=loamy sand, SL=sandy loam, L=loam, CL=clay loam, C=clay.
    b Hot water extractable B

    A. Deora, B. D. Gossen, F. Walley & M. R. McDonald, 2011, “Boron reduces development of clubroot in canola, Canadian Journal of Plant Pathology Volume 33, Issue 4

    Karamanos, R.E. Kruger, G.A. and J.W.B. Stewart, 1986.  Copper deficiency in cereal and oilseed crops in northern Canadian prairie soils.  Agron. J. 78: 317-323.

    Goh, T. B. and Karamanos, R. E. 2006. Copper fertilizer practices in Manitoba. Can. J. Plant Sci. 86: 1139–1152

    McAndrew, D.W., Loewen-Rudgers, L.A., and Racz, G.J., 1984, “A growth chamber study of copper nutrition of cereal and oilseed crops in organic soil,” Can. J. Plant Sci. 64: 505-510

    Karamanos, R.E. provides the following copper recommendations for Canadian Prairie soils, which he developed from Westco Fertilizer’s (now Viterra) database for the AgroMax series of tip booklets.

    Copper recommendations for non-cereal crops.

      Soil testProbability of precipitation
    TextureaOrganic matterCub range ppm75%50%25%10%
       lb Cu/acre
    S, LS, SL <1% 0 - 0.2 0 3.5 3.5 3.5
      <1% 0.21 - 0.3 0 2.5 2.5 2.5
      <1% >0.3 0 0 0 0
      >1% & <2% 0 - 0.2 0 0 3.5 3.5
      >1% & <2% 0.21 - 0.3 0 0 2.5 2.5
      >2% 0 - 0.2 0 0 0 3.5
      >2% 0.21 - 0.3 0 0 0 2.5
      >1% >0.3 0 0 0 0
    L, CL <2% 0 - 0.2 0 0 0 3.5
    L <2% 0.21 - 0.3 0 0 0 2.5
    L, CL <2% CL>0.2; L>0.3 0 0 0 0
    L, CL All All 0 0 0 0

    a S=sand, LS=loamy sand, SL=sandy loam, L=loam, CL=clay loam, C=clay.    
    b DTPA extractable Cu.

    Ross McKenzie, 1992, Micronutrient Requirements of Crops, Alberta Agriculture and Rural Development, Agdex 531-1

    Rigas E. Karamanos, “Micronutrients – When Should We Use Them?”

    Karamanos, R. E., Pomarenski, Q., Goh, T. B. and Flore, N. A. 2004. The effect of foliar copper application on the grain yield and quality of wheat. Can. J. Plant Sci. 84: 47–56.

    DeMilliano, Emile and Karamanos, R.E., Viterra. Described in a Top Crop Manager article by Bruce Barker in the October 2011 West issue. Link: http://www.mydigitalpublication.com/display_article.php?id=841338

    Karamanos, R.E. “Micronutrients – When Should We Use Them?”

    Marschner, H. 1986, “Mineral nutrition of higher plants,” Academic Press Inc., London UK, 674 pp.

    Grant, C.A., and Bailey, L.D. 1993 “Fertility management in canola production,” Can. J. Plant Sci. 73: 651-670

    Grant, C.A., and Bailey, L.D. 1989 “The influence of Zn and P fertilizer on the dry matter yield and nutrient content of flax on soils varying in Ca and Mg level,” Can J. Soil Sci, 69: 461-472

    Rigas E. Karamanos, “Micronutrients – When Should We Use Them?” The recommendations for zinc sulphate, oxysulphate and chelated zinc come from this paper.