Newsletters / Archives / Canolafokus Archives / 2011 Canolafokus No 48

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Canolafokus 48   Augustus 2011


Minimising your canola harvest losses

Dr Johann Strauss
Institute for Plant Production, Department of Agriculture Western Cape (johannst@elsenburg.com)

Significant seed losses can occur due to natural shedding and crop disturbance by harvesting machinery. The farming community of the Western Cape has raised questions about the difference between the potential yield of canola (as indicated by several seasons of canola cultivar trials) and the actual (or realized) yields achieved by producers and delivered to the silo. Avoidable seed losses currently exacerbate the perception that canola production is less profitable than wheat production. During the past three years a study was done to quantify canola harvest losses in the two different harvesting methods that are prevalent in the Western Cape.

Tabel 1
Summary of year effect on the canola harvest loss trial
Year In-season rainfall (mm) Potential yield (kg/ha) Actual yield (kg/ha)
2008 308 2 902 2 135
2009 322 2 466 1 963
2010 192 1 528 1 305

The potential and actual yields are shown as an average value for each season. The important "take home" message from this table is that it is important to manage the crop according to the season and to minimize the losses that can occur, because the producer can manage the losses, but cannot control the weather. It is important that we manage our canola in such a way that we get the maximum in the harvester.

Harvesting methods

One of the questions asked most is which of the two methods of harvesting (swathed or straight combined) is the best. When the two methods are compared over the three year period it was shown that there was no statistical difference between the percentage seed loss in the two methods (Table 2), in fact it was similar. It does not matter which method is used, but how well the method is managed.

Tabel 2
Significant differences (95% confidence level) of main data observations
Harvest method Yield (kg/ha) Pre-harvest losses (kg/ha) Losses with harvest (kg/ha) Total losses (kg/ha) Percentage loss (kg/ha)
Swath 1 872 A 34 A 235 A 297 A 20 A
Straight 1 716 B 30 A 229 A 254 B 20 A

From the data collected over three seasons there was a significant difference between the actual yields of the swathed and straight combined canola. Swathed canola showed significantly higher average yield than the straight combined canola, with 1 872 kg/ha and 1 716 kg/ha respectively. A major factor contributing to these yield differences was the stormy conditions experienced in the 2009 season which caused severe pre-harvest losses in the straight combined canola. The straight combined plots showed average yield losses of 375 kg/ha compared to the swathed canola losses of 33 kg/ha.

Tabel 3
Year effect on main parameters
Year Yield (kg/ha) Pre-harvest loss (kg/ha) Harvest loss (kg/ha) Total loss (kg/ha) Percentage loss (%)
2008 2 136 a 27 b 724 a 750 a 26 a
2009 1 963 b 204 a 299 b 503 b 20 b
2010 1 305 c 34 b 181 b 214 c 14 c

The difference between harvest losses of the three seasons was subject to management of the trials (Table 3). The 2008 season was harvested according to the standard practice of harvesting canola near 8% moisture content. This proved to be a risky practice since the fruiting bodies (pods) are very dry and subject to shattering, causing higher losses. From 2009 onwards it was decided to harvest at higher moisture content of between 13% and 14%. This proved to be a revelation. Harvest losses dropped significantly for the last two seasons. This fact is also reflected in the total losses and percentage loss. The 2009 results would have been more in-line with the 2010 results if the trial was not subjected to the windy conditions.

The data suggests that there were no differences between swathed and straight combined canola in terms of percentage crop loss over the three year cycle. Differences on a year to year basis may vary between the two methods of harvesting, depending on climatic conditions in straight combined canola and timing of swathing the crop. The decisions to harvest at an higher moisture content has definitely improved the harvest losses and stresses the fact that correct management of the crop is imperative for a successful yield even under the given set of climatic conditions. The statistical significant difference between the total harvest losses between the two methods might have been skewed due the drastic losses experienced in the 2009 season in the straight combined plots. This is however a reality of the crop during the ripening stages.

From the experience gained from the trial the following pointers are suggested:

  1. Swath the crop in areas prone to very strong winds especially during ripening.
  2. Ground speed of the swather and the swather rake speed must be similar to ensure a smooth cutting of the crop since losses of up to 150kg can be experienced in the swathing action alone. This also relates to the pick-up action when crop is mature, where a smooth intake of the canola is essential to minimize losses. Another important note is that the size of the windrow must be such that the harvester can handle it effectively.
  3. Swath at the correct stage of seed ripeness (55% seed coloration). Coloration percentage is determined by picking random pods across the camp, one pod per plant from the main stem. If the color of 55% of the seed screened is not green anymore it is time to swath. The might be necessary to start swathing from 45% seed coloration onwards if large areas have been planted to canola, since the crop is only at the correct stage of ripeness for around 3 to 4 days.
  4. Correct cutting height for swathed crop – preferred height is just above the first branch – this will help with to protect the windrow against wind and ease the pick-up action of the harvester.
  5. Harvest from 13-14% moisture – higher losses occurs the drier the crop. Harvest from early morning till around 11 o'clock (maybe later depending on cool conditions), then from 4 o'clock onwards till such time that the crop becomes to moist.
  6. If the crop is desiccated to ensure even ripening in a straight combined camp, it had to be done at 75% to 85%. If done earlier it could mean a larger amount of unfilled seed, which in turn relate to lower crop yield.

Hantering van canolasaad tydens die oesproses

SOUTHERN OIL LTD
P.O. Box 707, Koringlandstraat, Swellendam 6740
SOILL logo

Na 'n paar onverklaarbare klagtes oor die kwaliteit van Southern Oil se B-Well canola-olie het hulle met 'n in-diepte ondersoek begin na die moontlike oorsake van sulke klagtes. Die slotsom was dat die hantering van saad direk na die oesproses 'n kritieke rol speel in die uiteindelike kwaliteit van die olie wat aan die verbruiker gelewer word.

Die klagtes het almal min of meer verwys na 'n erge vis reuk wat onhoudbaar word as die olie verwarm word. SOILL se kwaliteits­personeel het die bêremonsters van die spesifieke lotte getrek en presies dieselfde waargeneem. Waar die olie normaalweg steeds baie goed is na 'n raklewe van 2 jaar, het hierdie spesifieke lotte binne 2 maande so verswak in kwaliteit dat die olie onbruikbaar geraak het. Die skade aan die handelsmerk en die beeld van canola is natuurlik geweldig. SOILL het in 2010 HACCP status verwerf en het dus 'n goed gedokumenteerde en geïmplementeerde kwaliteitstelsel in plek. Die ironie is dat geen toetsing van die saad of die olie enige defek aandui voor versending nie.

Hantering van saad

In hul soeke na moontlike oorsake het die span van Southern Oil eerstens intern begin en die beproefde prosesse van voor af geskrutineer met die hulp van internasionale spesialiste. Die hantering van canola van die plaas tot by die verbruiker is in detail ge-analiseer en vergelykings is met internasionale praktyke getref. Enkele aanbevelings is geïmplementeer, maar die grootste afwyking van internasionale praktyke blyk die hantering van saad direk na die oesproses te wees.

'n Duitse studie het bewys dat canolasaad by 7% vog ge-oes moet word of alternatiewelik direk na oes gedroog moet word tot 7% vog. Die studie het verder bevind dat deur die saad selfs net oornag natter as 7% te berg veroorsaak ernstige en onherstelbare skade aan die kwaliteit van die olie in die saad. Die stoor van natter saad versnel die formasie van negatiewe sensoriese eienskappe in die olie – tipies wat ondervind is in die spesifieke gevalle.

Hier plaaslik het dit 'n boerderybestuurspraktyk geword om die saad natter te oes ten einde oesverliese te beperk. Die saad word dan heel dikwels in store afgelaai vanwaar dit later na die fabriek uitgelaai word. Tydens gradering by die ontvangspunt kan slegs erge degradasie van die saad waargeneem word in die vorm van 'n suur reuk, muf of uitgeloopte pitte. Sulke saad is vanselfsprekend nie geskik vir verwerking vir menslike gebruik nie. Ons weet egter nou dat beskadiging van die olie reeds plaasvind selfs tydens nie-ideale hantering na die oesproses wat nie lei tot enige waarneembare defek op die saad nie. Hierdie praktykte het reeds die bedryf tot op datum baie skade berokken.

Samewerking tussen produsent, werwingsinstansie, logistieke verskaffer en opberger

Southern Oil besef hoe belangrik dit is vir elke produsent om sy opbrengs te maksimaliseer en vra nie hiermee dat alle saad droog geoes word nie. Die maksimum afsnypunt van 12% vog sal egter wel streng toegepas word. Wat nou baie belangrik word is die hantering van saad direk na die oesproses. Om die proses vlot te laat verloop gaan goeie samewerking tussen die produsent, die werwingsinstansie, die logistieke verskaffer en die opberger vereis. Southern Oil koördineer die proses na die beste van sy vermoë, maar maak staat op almal se insette om hierdie risikos te help bestuur.

Om potensiële bottelnekke in die hantering van canolasaad aan te spreek, is Southern Oil in die proses om 'n droër by sy fabriek op Swellendendam te installeer, terwyl SSK ook besig is om addisionele drogingskapasiteit te skep. Die bottelnekke wat in die verlede by die ontvangspunte voorgekom het, behoort dus geskiedenis te wees, ten spyte van die belowende oes op hande.

Deur goeie samewerking kan die canolabedryf aan die verbruiker produkte van hoogstaande gehalte met selfvertroue lewer. Dit is absoluut noodsaaklik om die aspirasies van die bedryf te bevorder.


Enquiries / Navrae

Directorate Plant Sciences, Department of Agriculture Western Cape
Direktoraat Plant Wetenskappe, Wes-Kaapse Departement van Landbou
Private Bag/Privaatsak X1, Elsenburg 7607   T. 021 808 5321   E. pietl@elsenburg.com

Editors / Redaksie

PJA Lombard   J Bruwer   Prof A Agenbag   Izane Leygonie
Sponsored by the Protein Research Foundation
Geborg deur die Proteïennavorsingstigting

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