No "mongrel" in mungbeans

As mungbeans shed their “mongrel beans” reputation and establish themselves as “money beans” recent research has shown that when growers plant into the right paddock conditions around a third of them will achieve their maximum yield potential for each season.

However, the GRDC funded mungbean paddock survey has found that almost half of some growers are missing out on up to half-a-tonne yield per hectare by planting into less than ideal conditions.

In a collaborative project between researchers Dr Marisa Collins, University of Queensland, Gatton, and Dr Lindsay Bell, CSIRO Toowoomba, respectively, a combined approach of sampling grower paddocks and modelling to assess yield potential compared to growers' actual yields.

This captured both starting paddock conditions, including soil water, nutrient and nematode status, weed/insect/disease pressure combined with weather data to assess the yield potential for each paddock and compared that to grower yields in 70 grower and research paddocks from Central Queensland, across the Darling Downs, Moree and down to the Liverpool Plains, NSW in the 2017-18 season.

"When we matched that with paddock samples and the paddock data to work out what was driving yield cuts two things came out," Dr Collins said. "More than half the growers had a yield gap of more than 500 kilograms or half-a-tonne per hectare.

Of growers with large yield gaps nearly 90 per cent had one or more of the following: starting soil Nitrate N less than 65 kg/ha, or nematode (P.thornei) counts more than 3 g/soil, or maximum temperatures above 39 degrees centigrade during flowering.

"The other thing that the project confirmed was that in comparing double crop and fallow mungbeans, there was a significant yield advantage (+200 kg/ha) driven by the extra stored soil moisture available on fallow (+27mm), DSr Collins said.

“When it came down to it the differences we saw between fallow and double-crop mungbeans was just the starting soil water.

Highest yielding paddocks in the survey (up to 2.5 t/ha) had good starting water and lucky enough to have favourable seasonal rain and were planted onto narrow rows.

Row spacing’s under 40cm yielded 33pc higher than crops on row spaces more than 50cm, and crops achieving yields higher than 1.25 t/ha generally required a minimum of 200mm of available water (starting soil water and inseason rainfall).