Spring-sown canola delivers fodder and grain

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Switching from autumn to spring sowing is showing huge promise for fodder and grain, according to recent Grain & Graze research

Spring-sown canola can provide valuable summer and autumn fodder, as well as go on to produce grain with little or no yield penalty relative to autumn-sown crops, according to recent Grain & Graze research in the high-rainfall zone of southern Victoria.

Photo of sheep grazing spring-sown canola

Grazing spring-sown canola had no impact on final grain yield while delivering 3t/ha of high-quality sheep fodder during the extremely dry summer/autumn of 2013. The spring-sown canola compared very well to the commercial forage rape Winfred in terms of summer feed supply.

PHOTO: Annieka Paridaen

Southern Farming Systems researcher Annieka Paridaen says one of the biggest benefits of spring-sown canola is that the crop can make the most of summer rainfall and establish at a time when there are fewer threats to plant growth.

The pros and cons

The benefits of sowing in spring:

  • reduces work pressure during autumn;
  • makes use of summer rainfall;
  • supplies large amounts of feed in summer and autumn;
  • results in an established, vigorous crop by autumn, which is less likely to fall victim to slugs and waterlogging;
  • means paddocks are sown before they get too wet in autumn/winter; and
  • results in two ‘crops’ (fodder + grain) from one sowing pass. 

Potential threats/limitations:

  • weed numbers and weed control are a concern in long-season crops;
  • pests occur at establishment in spring/summer including slugs, redlegged earth mites and diamondback moth; and
  • insufficient moisture present over summer and autumn resulting in low plant numbers.

“In our 2011-12 trial, 80 millimetres of rain in May 2012 and a further 75mm in June left a lot of the site pretty much under water, which made access to sow and manage autumn crops very difficult.”

In contrast, canola plants sown during the previous 2011 spring were, by May 2012, well and truly established, with taproots of 300mm.

“The spring-sown plants were resilient and mature enough to be unaffected by the slugs and redlegged earth mites that posed a real threat to emerging autumn plants and demanded costly treatments,” Ms Paridaen says.

A common concern with spring-sown canola is its ability to recover from grazing during a very dry summer and autumn.

“This occurred in our 2012-13 trial, with the spring-sown canola pretty much deprived of rain until the break occurred in May 2013, apart from 40mm of rainfall two weeks after sowing in November 2012.”

The research team were unsure that the spring-sown plants could bounce back from the three grazing episodes on top of the dry and hot conditions.

“But the crop surprised us and came back with flair,” Ms Paridaen says.

“By the time we were sowing the autumn crop in May 2013, the spring-sown and grazed plants were well on their way to becoming a viable commercial canola crop, without the threats posed by slugs, redlegged earth mites and cold, wet conditions over the winter.”

2011-12 trial

Grazing management

Grazing commenced at the end of January 2012 when three tonnes per hectare of good quality dry matter was available. The crop was grazed with dry ewes stocked at 26 dry sheep equivalents (DSE)/ha.

Just over 4000 kilograms/ha of dry matter was removed over 55 days of grazing.

The feed quality of the canola was high, with metabolisable energy (ME) averaging 13.5MJ/kg dry matter and protein up around 22 per cent.

Ms Paridaen says nitrate poisoning was not a concern in 2012, with levels well under the toxic threshold of 1000 milligrams/kg for lambs. “But introducing stock to forage brassicas needs to be done gradually and it is important that stock are not put onto canola with an empty stomach,” she explains.

It can take a few days for stock to develop a taste for the canola, Ms Paridaen says, with almost every other plant in the trial area eaten before the sheep started on the canola.

“Monitoring feed levels during grazing is important, as it did not take long for the sheep to completely eat the paddock bare once they became accustomed to the canola.

“In the 2012 trial, the third and final grazing was much heavier than planned due to the sheep eating it down very quickly.”

Grain yield

Grazed canola yielded more than ungrazed canola in the 2011-12 trial, with nearby spring-sown ungrazed plots yielding 1.9t/ha compared to 2.7t/ha for grazed plots. Nearby canola (CB™ Taurus) sown at the conventional time (April) yielded 2.3t/ha.

Grazed plants had more branches and a denser canopy than ungrazed plants.

The number of times the crop was grazed had no significant impact on yield. Grazing twice yielded 0.1t/ha more than a single grazing and 0.2t/ha more than grazing three times (Table 1).

Grazing (no.)
Intensity of grazing
 Grazing times
 Days grazed
 DM consumed cumulative (kg/ha)
 Grain yield (t/ha)
Table 1 Dry matter production and grain yield for spring-sown CBTM Taurus canola at Dunkeld, Victoria, 2012.
 1  Light  31 Jan –
22 Feb
 22  494  2.8
 Heavy  31 Jan – 5 Mar

 34

 2316  2.5
 2  Light 31 Jan – 22 Feb 29

  2763

 2.9

29 Mar – 5 Apr
 Heavy 31 Jan – 5 Mar  46  2944  2.5
29 Mar –10 Apr

 3

 Light 31 Jan – 22 Feb  36  3488  2.7
29 Mar – 5 Apr
26 Apr –
3 May
 Heavy 31 Jan –
5 Mar
 55  4031  2.4
29 Mar –
10 Apr
26 Apr – 7 May
LSD (p=0.05)  NS

SOURCE: Annieka Paridaen, Southern Farming Systems

“Although there was a yield penalty by grazing three times compared to two, the third grazing supplied an additional 1t/ha of high quality feed at the beginning of May,” Ms Paridaen says.

Heavy grazing reduced yield compared to light grazing, irrespective of grazing frequency. However, the reduction in yield was small and the heavy grazing produced 4t/ha of feed compared to 1.4t/ha when lightly grazed.

“When deciding on stocking rate and grazing intensity, it will be a trade-off between the value of the feed over summer and autumn and final grain yield,” explains Ms Paridaen.

2012-13 trial

Grazing management

Canola resilience was well and truly tested in the 2012-13 trial, with three very heavy grazing periods between the end of January and the end of April.

Ms Paridaen says plants were lost and for a while it seemed as if the crop would not recover.

But the thick starchy stem and root system of the established canola enabled the plants to hang on and they started to grow back once the break finally came.

“The recovery of the plants was just astounding,” she says. “By winter 2013 it was impossible to distinguish the grazed and ungrazed plots.”

The 2012-13 trial demonstrated that canola can recover from the stress of complete defoliation and still go on to produce a reasonable grain yield (Table 2).

Table 2 Dry matter production and grain yield for several winter canola varieties sown in spring 2012 and harvested in December 2013 at Inverleigh, Victoria.
 Variety  Time of sowing
 Grazing  Spring estab (pl/m2)
 Autumn survival (pl/m2)
 Reduction in plants (%)
 Summer  DM (t/ha)
 Grain yield manual harvest (t/ha)
 Taurus  Spring  Grazed  47  26  –43  2.5  4.0
 Ungrazed  42  30  –29  
 5.0
 Autumn    8      3.6
 Hyola 971 CL
 Spring  Grazed  41  28  –28  2.4  4.6
 Ungrazed  42  28  –28    5.2
 Autumn    14      4.4
 Hyola 930
 Spring  Grazed  42  26  –38  2.2  4.9
 Ungrazed  39  36  –4    5.2
 Autumn    11      4.1
 CB 143 CL
 Spring  Grazed  43  24  –44  2.3  4.2
 Ungrazed  38  30  –18    4.5
 Autumn    17      3.9
 CB Sherpa
 Spring  Grazed  38  24  –35  2.8  4.7
 Ungrazed  43  27  –36    5.2
 Autumn    Not sown
     –
Winfred
Spring
 Grazed  62  31  –49  2.8  –
 LSD  (P=0.05)
 12  7  NS  NS  0.8

SOURCE: Annieka Paridaen, Southern Farming Systems

The 2013 canola generated about one tonne less feed than the 2012 crop, but Ms Paridaen says the value of the green feed during the dry 2013 summer and autumn would most likely have outweighed the extra feed available in the more favourable 2012 season.

“It is difficult to put a price on almost three tonnes of high-quality green feed when there is nothing else around,” Ms Paridaen says.

More information:

Annieka Paridaen, Southern Farming Systems,
03 5265 1666,

aparidaen@sfs.org.au

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GRDC Project Code SFS00020

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