Topdressing Canola: Tips on how to Maximize the Advantages

By Mike Stamm and Dorivar Ruiz Diaz

To maximise the yield potential of winter canola, producers should topdress with nitrogen (N), sulfur (S), and presumably boron inside the winter. Producers should make topdress functions with consideration for the environmental conditions, the nutritional vitamins wished, and the making use of method.

Environmental conditions

The everyday time to topdress winter canola is thru the rosette stage. Normally this can be accomplished in January or February, since temperatures are chilly enough to keep up canola on the rosette stage. Present drought conditions for a lot of of Kansas might pause topdressing presently until moisture is available on the market to incorporate the fertilizer into the soil.

In primary, temperatures by the canola rising season have been hotter than common with just some durations beneath common. Temperatures have been chilly enough that we’re seeing the usual winter response of white and brown colors as leaves free chlorophyll. When these leaves are pulled once more, practically all of plant crowns are inexperienced and company, indicating the vegetation are alive. Nonetheless, remaining winter survival scores should not be taken until the crop begins to interrupt dormancy and after the specter of further chilly temperature loss has handed.

Below all circumstances, producers should confirm their fields for surviving vegetation sooner than making use of a topdress software program even when there is not a priority for poor winter survival (Determine 1). The place stand thinning is observed, it may very well be advisable to attend until canola is actively rising as soon as extra sooner than topdressing. It will assure that there is passable spring stand to take to reap.

Determine 1. Canola beginning to interrupt dormancy on the relevant time for topdressing. 


A mixture of nitrogen and sulfur might be utilized inside the topdressing combine.

Nitrogen. About two-thirds of the total N wished by the canola crop have to be utilized as a winter topdress. This can be carried out at dormancy or as vegetation begin to point out elevated growth, nevertheless sooner than the vegetation bolt. The trigger is that N uptake will improve shortly sooner than bolting. Topdress functions have to be based totally on an updated analysis of yield potential, a lot much less profile residual N, and the amount of N utilized inside the fall.

Instructed N prices for five yield ranges and a soil with 2 % pure matter and ranging residual nitrate-N ranges is confirmed in Desk 1.

For soils with 1 % pure matter, add 15 kilos N for each yield and nitrate diploma. For soils with 3 % pure matter, subtract 15 kilos N for each yield and nitrate diploma.
Desk 1. Whole nitrogen fertilizer desires for canola as affected by yield potential and soil check out nitrogen ranges inside the southern Nice Plains (from Nice Plains Canola Manufacturing Handbook:

Profile N check out Canola yield potential
lb/acre lb/acre
1,500 2,000 2,500 3,000 3,500
0 75 100 125 150 175
20 55 80 105 130 155
40 35 60 85 110 135
60 15 40 65 90 115
80 0 20 45 70 95
100 0 5 25 50 75

Both secure or liquid forms of N might be utilized. As soon as the local weather warms and growth begins, functions using streamer bars or secure provides are most popular for broadcast functions to forestall/stay away from leaf burn.

Managed-release merchandise akin to polymer-coated-urea (ESN) may very well be considered on very sandy soils susceptible to leaching, or poorly drained soils susceptible to denitrification. Usually, a 50:50 mixture of unusual urea and the coated urea — which is ready to current some N immediately to help bolting and flowering and likewise proceed to launch some N in later ranges of development — works best in settings with extreme loss potential.

Sulfur. If canola is poor in S, the implications could also be very crucial on account of the crop desires S to provide protein inside the seed. For this trigger, soils having decrease than 20 lb/acre sulfate-S inside the larger 24 inches should receive supplemental S. An awesome rule to look at is to keep up S-to-N availability at a ratio of about 1 to 7. One other straightforward guideline is to make use of 20 lb S per acre, which can most likely be sufficient for low and medium yield ranges. Sulfur could also be utilized inside the fall and built-in into the seedbed or surface-applied with N inside the winter topdressing. Canola growers may consider using elemental S, or sulfate varieties (e.g. ammonium sulfate, or liquid ammonium thiosulfate). Since elemental S ought to oxidize to show into plant obtainable, it should solely be utilized inside the fall. Ammonium thiosulfate or ammonium sulfate could also be utilized inside the spring or fall, nevertheless thiosulfate should not be topdressed immediately on inexperienced tissue or positioned with seed to stay away from short-term phytotoxicity.

Boron. If poor, boron is one micronutrient which will have detrimental penalties on canola yield. Usually, boron deficiency won’t be one factor now we have now seen in Kansas. Nonetheless, if there are micronutrients which may have an effect on yield, then boron might be one amongst them. Probably the most important issue is to know what your soil sample states. Making use of boron may help to reduce flower abortion and permit setting pleasant pod filling. Nonetheless, there’s not loads room for error when evaluating passable boron fertility ranges and toxic ranges which will finish end result from over software program. Due to this, software program prices of boron are generally 1.0 lb per acre or a lot much less. Soil and foliar functions of boron are environment friendly. Foliar functions could also be made with herbicides, and soil-applied boron could also be each broadcasted or banded. Make constructive functions are uniform all through the sector to stay away from toxicity, and stay away from contact with the seed for band-applied boron.

Software method

It’s important to stay away from crushing winter canola with giant appli­cator tires. Crushed vegetation will lodge and matu­rity will most likely be delayed, which could sluggish harvest and improve the hazard of shattering losses. For this trigger, applicators with slim tires are most popular. As for the question of whether or not or not broadcast or banding is best — if temperatures are chilly and the vegetation are dormant, topdress fertilizer could also be broadcast. If temperatures are delicate enough that the canola vegetation have resumed vigorous growth, it may very well be best to utilize streamer bars or one other sort of banded software program to stay away from foliar burn.

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