Doing some calculations this week about how long I have been talking, mixing, trialling, digging up legume plants, assessing and devising new and better ways to apply your Rhizobia Bacteria to our legume seed crops.
Started with my family farming background growing lots of soybeans in the South Burnett and my role as chief mixer of the peat inoculant slurry, containing these live Rhizobia Bacteria, onto to the soybean seed in the shade of course. Heat, needless to say, is a major destroyer of our live bacteria and really it’s not that much heat. Over 25 degrees is enough to damage these fairly sensitive microscopic bacteria and over 30 degrees C, they can perish fairly quickly.
My second set of instructions was mixing cool clean tank water in with the peat inoculant and spreading this wettish black slightly gritty mixture all over the soybean seeds.
Then to load this newly mixed batch of inoculated seed into the precision planter for immediate planting into a moist soil with our pH of around 7.5. They, the bacteria are not keen on any companion products in the water either, be it water injection or the slurry method.
Now this was many decades ago and what has changed??
Certainly we push the envelope to the edge for this fairly labour intensive job with cement mixers, augers and liquid spray applicators and even dry applications into large seed hoppers full of legume seeds that need inoculation.
How effective is the fruits of our current labours in achieving success with this very important process, given our Rhizobia strains have improved since those long ago farm days of mine?? How many of us actually DIG up our growing legume plants to check our inoculation success..?? Not just pull them out please.
Let remind you that these live bacteria that inhabit these root nodules can have a symbiotic relationship with this leguminous plant, plus derive free nitrogen from the atmosphere. We call it NdfA or Nitrogen derived from the Atmosphere.
That is a very cheap nitrogen source and a very desirable form of nitrogen for these plants. Now legume plants do need plenty of nitrogen and our pulse crops like Chickpeas and Mungbeans need plenty of N to produce the high protein grains, which we can export to desirable overseas markets.
For example to produce 1 tonne per hectare of Mungbean seed, the plant needs 60 to 70 kgs per ha of plant available Nitrogen. For two tonne per ha it is more like 110 kgs per ha of Nitrogen or more and so up the yield table.
No wonder I am so keen on promoting and assessing our success in nodulation score (1 to 5) on our legume plants, particularly our clean green Mungbean crops. The Mort and Co granule certainly works well as a carrier for these microbes, when infused or has rhizobia inoculant applied to it for inclusion in your legume planting operation. Plus given you have enough capacity hoppers on your planter, it can be a one shot operation.
The other key learning for me over the years is being confident that the inoculant is still alive, after transport from place of manufacture to you the grower and agronomist.
In summer time that really needs some thought and confidence in the supply chain or even your own refrigerator system and please don’t freeze the peat product or leave packets of inoculant in the back of Ute for several days.
Grow your Mungbeans or legume crops with confidence of a good return, especially when you get the inoculation process correct to maximise your yields.
That’s all folks.
Paul McIntosh has been involved in providing broadacre agronomic support since 1977. Since 2015, Paul has held combined roles with Pulse Australia and Weedsmart, as an industry development and extension agronomist. His regular weeds column is published in a number of places including New England Times Engage.
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