Benchmarking project to demystify mungbean yields
GroundCover™ Issue: 134 May - June 2018 | Author: Liz Wells
Factors including nutrition, water, heat and light are being looked at in the GRDC-funded ‘Optimising mungbean yields’ project, which is bringing together researchers, private agronomists and leading growers to find out what determines pod set in Australia’s key summer pulse
Mungbeans are Australia’s largest summer pulse crop, but what determines their yield is not well understood. That looks set to change with a new GRDC-research investment, the ‘Optimising Mungbean Yields’ project, which has started this year under the leadership of Gatton-based University of Queensland (UQ) researcher Dr Marisa Collins.
“The main aim is to benchmark yield and potential drivers of mungbean yield in double-cropping and in fallow,” Dr Collins says.
She says the project will look at factors such as soil nutrition and starting water, nematode pressure, rainfall and temperature, and how they affect indicators such as biomass and flower-to-pod ratio.
Mungbeans entered crop rotations, mainly in Queensland and northern NSW, as a double-cropping option to follow wheat when ample soil water was available.
The Australian Mungbean Association (AMA) has found that about 40 per cent of mungbeans are double-cropped straight after wheat. Yield variability is a problem for these crops, as well as ones planted into fallow.
“Even under good conditions, mungbeans can unexpectedly return poor yields, and part of the problem with addressing that challenge is that we don’t understand what drives yield.”
The first stage of the project has established benchmarking trials on private farms: 12 in Central Queensland, 18 on the Darling Downs, and 12 in total on the Liverpool Plains and the Moree district in northern NSW.
“We want to learn from growers, as well as get some hard data around observations, to provide some metrics around what yields can be expected.”
The trials have also enlisted the help of AMA-accredited agronomists to manage and monitor the crops. Most trial paddocks are dryland, but some are irrigated or semi-irrigated. An additional site that uses shade structures to identify the critical window for determining yield in mungbeans has been established at UQ’s Gatton Campus.
While sorghum is by far Australia’s biggest summer crop and has better drought tolerance than mungbeans, many growers plant the pulse annually or occasionally because of its shorter growing season and lower water use than the summer grain.
Other advantages of mungbeans are its indeterminant nature, which allows it to flower and set pods in response to in-crop rain events, and its ability to fix nitrogen in the soil.
However, mungbeans’ response to applied nitrogen is poorly understood.
As a pulse, mungbeans generally fix their own nitrogen, but growers are asking whether they should fertilise them as they do other summer crops.
“We also don’t understand the impact on yield and physiological maturity if mungbeans are planted into paddocks that were prepared for cotton or sorghum and have 100 kilograms per hectare of nitrogen applied in September,” Dr Collins says.
“We know they won’t be fixing any nitrogen but if that happens, what sort of yield can growers expect? That’s the kind of question that growers are starting to ask. We want to be able to say: ‘If you are going to double-crop them, or plant them into fallow, these are the sorts of things you can do to improve your yields’.”
The ‘Optimising mungbean yields’ project aims to lift the average national yield to two tonnes per hectare from 0.9t/ha, and has been welcomed by the AMA.
“Even if we can take those baby steps and lift the average to 1.2 to 1.3t/ha it will help to make our supply to export markets more consistent throughout the year, especially as opportunities in north Queensland develop,” AMA president Mark Schmidt says.
“It’s the best summer legume we’ve got. In Queensland, it’s crept up in tonnes over soybeans and peanuts, and there is a lot of potential in the north, where the crop can be growing over winter as well as in summer.
“We’d like to increase the size of the crop to 170,000t per annum, but we’ve only achieved that once – our biggest hindrance has been dry weather, or rain too late in the growing season.”
Mr Schmidt says the high prices seen in recent years encourage occasional growers into the market.
“Some growers will swing in and out of mungbeans based on pricing, and experience says they will grow an average to mediocre crop.
“Through our accredited agronomists course, we’re trying to make sure people making decisions about crops are trained correctly so everyone has the chance to grow the best crop they can.
“The data our industry will get from the ‘Optimising Mungbean Yields’ project will help us to achieve that.”
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