Six steps to soybean success
Points summarised from a presentation by Crop Physiologist, Dr Fred Belows at the Australian Summer Grains Conference 2019.
Australian context provided by Andrew McDonald, PB Agrifood
Under ideal growing conditions, soybeans can produce 12.18 t/ha. In the USA, the average yield is 3.5 t/ha across all soybean growing regions. The Australian average is 1.7 t/ha.
In the USA, soybean is commonly grown in rotation with maize (corn) where it can boost maize yields by 1.6 t/ha through improved soil health and tilth.
A 5-year research program led by Dr. Fred Below, University of Illinois identified the impact of six key management decisions on soybean yield.
The 6 steps are listed in order of their impact on yield. Management factors are partially additive when combined into a 'high tech' package. Basic principles of agronomy, such as attention to soil pH, inoculation and seed quality are assumed to be in place.
Step #1 – Weather
Soybean plants are sensitive to daylength and must be planted in the correct window to ensure they reach their yield potential.
Maximum yields are achieved when the day length is long and daytime temperature is reasonably even throughout the growing season.
Step #2 – Fertility
Fertilise soybean crops to provide the nutrient levels that will be removed for the grain yield you expect.
When it comes to nitrogen, soybean plants can 'fix' about half their N-requirement if the plants are properly nodulated. The plant will require 70 kgN per tonne of grain produced (and half of this will need to be applied as fertiliser at planting and at R3 growth stage).
Step #3 – Crop protection
Protect the crop from insect pests and fungal pathogens from the start of podding (R3 stage).
Step #4 – Varieties
Choose the variety that suits the location and planting window.
Take notice of the planting window recommendations for each variety and do on farm trials if necessary to assess the impact of planting date in your environment. If you find the pods are mature and the plants are still green, this is an indication that the crop was planted outside the optimal window. [too late? or too early?]
Planting in January can suit many Australian varieties and take advantage of the natural scenesence (leaf drop) attribute of newer varieties (reducing the need to apply desiccants prior to harvest).
Step #5 – Row spacing
Narrower rows and optimal plant populations work together to increase yield while reducing the risk of lodging. Where possible, sow soybeans in rows 50 cm apart or narrower.
Step #6 – Seed treatment
Applying extra rhizobium inoculant at planting can be a very worthwhile and cheap practice. Some Burdekin growers are having good success with higher yields after triple-inoculating their seed.
2018 6-step soybean research summary report
This video is from the 2013 Farm Journal Soybean College, sponsored by the Illinois Soybean Association, at the Crop-Tech facility in Heyworth, IL. The session Six Secrets of Soybean Success was presented by Dr. Fred Below, University of Illinois Agronomist.
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