Time of Sowing: Can we reduce stubble loads without sacrificing return? Spring Sown Barley

Author: Ian Herbert, SFS Tasmania        SFS_FINAL_Logo

Key messages

  • Planet and Westminster Barley were sown at Campbell Town on 2 October 2017 and harvested 8 February with average yield of 2.76 t/ha.
  • There were significant yield differences between varieties and some treatments which would suggest productive gains are available for growers through careful planning and management of spring sown barley crops.

 

Trial Details

Location:                Campbell Town, Tasmania

Sowing date:          2 October 2017

Rotation:                 Spring barley following failed autumn-sown canola

Variety:                   RGT Planet and Westminster

GSR:                         110mm (October–December)

Irrigation:              34mm

 

Aim

The aim of this fully replicate trial was to investigate how different management decisions would affect the performance of spring sown barley and how these decisions then related to the post-harvest stubble load.

Background

The longer seasons associated with the Tasmanian climate provide an opportunity for growers to sow traditional winter crops during spring and still receive reasonable yields during early summer. Due to the reduced length of the growing season growers need to develop strategies to ensure spring-sown crops perform at an optimum level — maximising yields, minimising stubble loads and maximising profitability.

Method

Two varieties of Barley (cv Planet and cv Westminster) were sown into a failed autumn-sown canola crop on 2 October 2017. The trial was designed as a fully replicated trial and the results where statistically analysed. Both varieties were sown at two different sowing rates with target plant populations of 200 and 250 plant/m2. The actual sowing rates varied due to differences in the 1000 grain weights of the varieties.

The previous failed Canola crop was sown with 120kg/ha MAP during April 2017. Minimal winter rainfall reduced the sowing fertiliser requirement for barley to 50Kg/ha, with much of the MAP from the earlier canola sowing still available.

Due to the dry conditions, limited water was available for the irrigated pivot circle containing the barley trials. The circle received 34mm of irrigation and approximately 110mm of rainfall during the growing season (October–December), much of which fell later in the season.

A significant frost event at the start of November impacted both varieties. Additional nitrogen (N) fertiliser was applied at GS14 to target an increase in yield by 1t/ha and 2t/ha above the control treatment (Table 1). The rate of additional nitrogen was applied was; zero for the control treatments, 50kg/ha for a 1t/ha increase and 100kg/ha for a 2t/ha yield increase treatment.

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Table 1 Trial details for spring-sown barley at Campbell Town, 2017

Results

Plant establishment

Plant establishment was assessed on 16 October for both sowing rates (Table 2) and varieties (Table 3).  While the higher sowing rate (250 seeds/m2) produced more plants per square metre at GS14, this did not translate to a significant yield difference at harvest (Table 2).

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Table 2. Plant counts and yield for different sowing rates*

Plant populations of each variety at GS14 were significantly different, with Planet exhibiting more seedling vigour, with more plants per square metre.

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Table 3. Average plant counts by variety at GS14, 16 October 2017

Dry matter production

Planet produced higher dry matter (DM) at GS 99 and as stubble load (post-harvest) than Westminster (Table 4).

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Table 4. Dry matter at GS99, 29 January 2018 and post-harvest, 9 February 2018, by variety

Yield and grain quality

The mean yield of both varieties combined did not increase significantly with additional nitrogen applied at GS14.  However topdressing with nitrogen increased the average protein content significantly compared with the control (Table 5).  Adding additional nitrogen over 50kg/ha (as applied for 1t/ha yield increase) did not significantly increase protein further.

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Table 5. Yield and protein response as a result of nitrogen application at GS14

Significant yield and grain quality differences were noted between Planet and Westminster (Table 6). Planet significantly out yielded Westminster and achieved lower screenings and higher test weights, although the protein content of the Westminster samples were significantly higher than those for Planet.

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Table 6. Barley yield, test weight, screenings and protein at harvest

Planet produced the best gross margins (GM) across all treatments with the average across both sowing rates being $254.66 compared with Westminster at $206.02 (Table 7). The increase in protein as additional nitrogen is added does not attract any premiums and decreases the gross margins by the cost of urea applications, by approximately $40/ha.

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Table 7. Average gross margin by variety

Discussion

The sowing of barley during spring is common practice in Tasmania for growers who want a low-cost, profitable short-term crop. Unfortunately, seasonal conditions during 2017–18 did not allow this trial to reach its yield potential.

Under the dryer conditions experienced, Planet out yielded Westminster and a comparison of gross margins revealed Planet to be more profitable than Westminster. The cost of seed was assumed to be the same for both varieties (i.e. it was retained by the grower from the previous harvest). If the cost of purchasing new seed for each variety was considered, the actual gross margin performance of varieties may also change.

Due to the low yields and lack of irrigation water, additional topdressing of nitrogen did not produce any additional yield, although it did increase grain protein levels. As protein levels where already above 15% without additional nitrogen it is unlikely any premium could be obtained to offset the additional costs incurred.

Given the high protein levels exhibited by both varieties it could be assumed that with a softer season, higher yields with lower protein levels would have been achieved, improving the gross margin. Conversely, due to the dry spring of 2017 no fungicide was applied to the crop, a common practice under wetter seasonal conditions. A fungicide application would also have affected the gross margin.

Stubble loads post harvest were minimal and most sowing equipment would have easily direct drilled the following crop direct into the barley stubble.

Acknowledgments

Thanks to the GRDC for their funding of the project, the farmers who hosted the sites and SFS staff for trial management.

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About BCG

Birchip Cropping Group Inc. (BCG) is a not-for-profit agricultural research and extension organisation led by farmers in the Victorian Wimmera and Mallee.
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