Australian Mungbean Association

Australian-grown mungbeans have quality written all over them!

After the rain – what are the options?

Kerry McKenzie, PulseAg.

 

21 February, 2020

 

Should I plant mungbeans now or save the moisture for winter crops?

by Kerry McKenzie, PulseAg

 

It has been a long time between drinks and now it has come in its usual summer way – patchy! Some have had good rain with neighbours much less. Now that mid-January has arrived it will lead to questions about how best to utilise the moisture that’s available.

A big question will be “Do I plant now or save for winter crop?” if the answer is Yes to planting now, the next question is “what do I plant?”

The vast majority of paddocks are devoid of cover and it will be a priority for many to establish some cover in the form of millets or sorghum. This will be important to maximise capture of follow up rain and limit erosion from heavy rain. However, this does not generate cash flow, which also needs to be considered.

Options for cash flow could be a forage crop of sorghum or corn for silage/hay. Consideration needs to be given to the amount of nutrient removed in the forage and possibly compaction issues. Millet and sorghum for grain are a longer shot, especially with the risk of ergot with late season sorghum.

Mungbeans are a good candidate for quick cash flow. They are a relatively short season crop and the current market prices are very favourable.

This is not to suggest that a late January plant is ideal for southern Queensland or northern New South Wales and the yields would not expected to be at full potential, however  the good prices and prospects for a harvest would make them a choice to strongly consider for cash flow.

Will they make it?

Mungbeans as a short season crop of around 90 days duration. The length of season is driven mainly by temperature and is influenced by the number of hours of sunlight during the day.

The estimated time to maturity can be estimated by using thermal time (growing degree days). Mungbeans require approximately 1200 day degrees (⁰Cd) and can be calculated using the average of the daily maximum and minimum temperatures minus a base temperature of 8⁰C. (*NB The variety Celera II has a lower requirement and will be quicker to maturity than large seeded varieties.)

 

E.g max temp 34⁰C and min 17⁰C = (34+17)/2 = 20.5 minus 8 = 12.5⁰Cd

 

If every day was the same as the example then it would take the crop 96 from plant to maturity. Every day is not the same and will be different for all locations as can be seen in Table 1. The below table is based on planting after this rain event on the 25th of January based purely on thermal time and has no allowance for shortening day length, it would be assumed that actual days to maturity will be somewhat longer.

 

Table 1 Average minimum and maximum temperatures for locations and days to maturity for mungbeans planted on the 25th of January (Source: www.bom.gov.au)

Using the estimates of time to maturity in Table 1 you can make some educated guesses as to whether the crop will make it through before the first frosts and cooler overnight temperatures leading into March and April.

The current Bureau of Meteorology long term forecast that was released on the 16th of January 2020 suggest that there is a higher chance of above average temperatures for the next 3 months and in particular it is the minimum temperatures that are likely to exceed the median temperatures (Figure 1). With minimum temperatures more likely to be above the median this would bode well for Mungbeans which have a critical minimum temperature of 15⁰C, temperatures below this will retard growth.

There is a risk that leading into the cooler months that the mean temperature (maximum and minimum) will be below 28-30⁰C which may lead to shorter internode lengths and overall plant height. This will need to be a consideration with regards to paddock selection.

Figure 1 Bureau of Meteorology seasonal temperature forecast issued 16th January 2020, chance of above median - a) February maximums, b) March maximums, c) Feb to April maximums, d) February minimums, e) March minimums, f) Feb to April minimums. (Source: www.bom.gov.au/climate/outlooks/#/overview/summary)

Other considerations

Some other topics to consider if deciding to plant Mungbeans in late January:

  • Plant Available Water – Mungbeans require a minimum of 75mm of PAW in the profile to ensure a crop is harvested, check infiltration after this rain event to determine there is at least this amount or more, and follow up rain is also required.
  • Residual herbicides – given the long dry what has been the history of herbicides and has there been sufficient time for risky products to have broken down.
  • Long fallow disorder – after a long time with no growth in paddocks there is a risk that AMF (previously known as VAM) levels have dropped, which may require increased rates of phosphorous and zinc fertilisers.
  • Disease – late planting time may lead to a higher incidence of halo blight in the crop – recommend using approved AMA seed. Powdery mildew will become prevalent late in the season with cooling overnight temperatures, check crop early, regularly and control at first sight.
  • Celera II – a small seeded variety, has a quicker maturity than large seeded types and finish up to 2 weeks earlier, however it has a limited market and having contact with a mungbean marketer before choosing this variety is advised.
  • Crop height – Crops may be shorter with a late plant, are you or contractor equipped to harvest shorter crops.
  • Weather at maturity – with lower temperatures dry down will be longer leaving the crop at higher risk from rainfall and downgraded seed quality. Use desiccation products if required at recommended rates and timings.

 

Further Information

 

Contact for more details

Email Kerry McKenzie – Pulse Check Coordinator
PulseAg Consulting

0467 650 252

Email Paul McIntosh
Pulse Australia
0429 566 198

Email Mark Schmidt
AMA President
Mobile: 0477 304 241

 

 

www.mungbean.org.au