Ian Herbert (SFS TAS)
The aim of this fully replicate trial was to investigate how the time of sowing and plant population would affect the performance of faba beans.
Inclusion of a grain legume in the Tasmanian cropping rotation is not wide spread. There is a perception that grain legumes are not as profitable as other crops and that there are limited markets for the grain within the state. Whilst these sediments are partially true it is imperative that there are legume grain options that grain producers can confidentially grow to produce reasonable profits. An inclusion of a legume crop in the rotation will provide other benefits such as residual soil nitrogen after harvest and an opportunity to use different strategies to control problem pests.
Due to the large amount of processed stock feeds consumed by the Tasmanian intensive livestock and aquaculture industries there is the potential to replace the imported faba bean portion of the ration with locally produced faba beans. At present the stock feed companies are importing directly from large mainland grain accumulators.
To achieve a critical mass of faba bean production to entice the feed mills to purchase locally, growers will need to produce more product, to achieve this they need more local production information including how sowing rate and timing affect yields to provide the confidence to grow faba beans.
The trial was designed as a fully replicated trial and the results where statistically analysed. The faba bean variety Rana was used in this trial and sown in an irrigated pivot circle at Cressy. The paddock had previously grown a poppy crop which was harvested one month prior to planting. The trial area was disced to reduce the chance of trash blockages in the plot seeder.
There were 2 separate times of sowing, the first sowing was carried out on 18 April, 2017 and the remaining plots were sown on 10 May, 2017. Each time of sowing had three different seeding rate treatments with the seeding rate reflecting target plant populations of 20, 30 and 40 plants/m2. The trial was sown with 100kg/ha of single super. Pesticide applications were applied as needed and in accordance with crop growth stages.
The trial received 380mm GSR and additional irrigations of approximately 200mm was applied during the season. The plots were impacted by the grazing of wild fallow deer during the growing season.
Time of sowing
The yield of faba beans from the different times of sowing treatments were significantly different as can be seen in Figure 1 below. The earlier sowing date of 18 April plots yielded on average 3.05t/ha. Whereas the plots sown on 10 May yielded average 2.13t/ha.
An increase in the target plant populations also produced a significant yield difference between the treatments across both times of sowing as can be seen in Figure 2 below. As the target plant populations increased the grain yield also significantly increased. The 20 plants/m2 plots yielded on average 2.24t/ha, with an increase of target population to 30 plants/m2 yield increased to 2.64t/ha and when the plant population was increased further to 40 plants/m2 the plots yielded on average 2.89t/ha.
The timing of sowing activities and target plant populations in this trial did significantly affect the grain yield of the various treatments. This trial demonstrated that an April sowing with a target plant population of 40 plants/m2 was the most profitable treatment. No additional costs were incurred at this sowing date, i.e. no additional fungicides or other chemicals were required. Unfortunately, the trial was impacted by grazing of wild fallow deer and yields were less than expected.
The challenge for growers is to have the confidence to strategically plant faba beans earlier than past practice and plant during their busy April sowing schedule. Small increases in sowing rates can also provide additional yield advantage and must be considered to maximise the grain yield potential of faba beans.
Thanks to the GRDC for their funding of the project, the farmers who hosted the sites and SFS staff for trial management.