Horsham grain grower Tim Rethus has been growing lentils as part of his cropping rotation for the past 25 years. He cannot speak highly enough of the legume as an alternative to chickpeas or faba beans.

This year he is looking to sow 1000 hectares of four types of (red) lentils on his dryland farm, all varieties bred in Australia – many at Horsham’s Grains Innovation Park or the South Australian Research and Development Institute (SARDI) – by plant breeders using seed lines originally imported from Syria in the early 1990s.

Tim uses lentils to put nitrogen back into his Wimmera black clay soils and to control weeds and soil-borne diseases ahead of his following annual wheat, barley and canola crop rotations.

The current varieties he sows include PBA Hallmark XT and PBA Kelpie XT, which are relatively disease tolerant and can handle spraying with Group B (now known as Group 2) herbicides post-sowing to control weeds.

Tim mainly grows the edible pulse because it is in high demand from consumers in Pakistan, Sri Lanka, India and Bangladesh, is easy to store on-farm for several years awaiting a favourable price cycle, and normally sells for a higher price than other legumes and plant-based proteins such as chickpeas, field peas, lupins and faba beans.

The current lentil price is about $1000 per tonne, but it has occasionally surpassed $1200/t. Tim estimates his lentil crops over the long term have averaged a yield of 1.5 tonnes per hectare, but they have achieved up to 2.5t/ha in good seasons, such as the past two years.

“The Wimmera is a great place to grow lentils. Usually most of the one-quarter to one-third of our farm that is planted to a pulse will be sown to lentils,” says Tim, who sows his lentils in late autumn into standing stubble to increase harvest efficiency in a crop that readily lodges when ripe.

“We prioritise our lentils when they are ready for harvest; we desiccate and get on to harvesting them as soon as they are ready. They have been a great crop for us.”

It is a strong endorsement of the benefits of hardy, high-value lentil crops that more Australian grain growers would like to be able to experience on their farms and in their cropping rotations.

Breeding and selection projects

That is why GRDC has recently invested in two new five-year breeding and selection projects involving lentils – one to improve the ability of lentils to grow on acidic soils in Australia, and the other to boost the yield stability of lentils growing in higher-temperature regions.

GRDC oilseeds and pulses manager Dr Francis Ogbonnaya says that while commercial lentil varieties have been introduced, selected and improved to grow well in Australia’s southern, medium-rainfall cropping zones such as Victoria’s Wimmera and South Australia’s Eyre and Yorke peninsulas, grain growers in NSW and Western Australia are much more restricted in the choice of legumes they can grow in their crop rotations.

“At the start it was about building the industry and commercialising varieties; our first commercial crop was only grown in 1994,” Dr Ogbonnaya says.

“But now we have growers in some southern parts who have been able to implement very good farming systems using lentils and make some good profits, and growers in other parts of Australia who are missing out.

“This new GRDC investment is to boost the pre-breeding programs of lentils to expand their geographical range and to ensure that in every part of the country there will now be a lentil variety that suits those conditions and can grow well in a crop rotation system, expanding the options to growers for legumes they can use.”

The past two seasons have seen a boom in lentil production as high prices have combined with good southern rainfall. The most recent Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) Crop Report showed 780,000t of lentils were harvested in 2021 (compared to 360,000t in 2018), with Victorian growers producing 350,000t and SA growers 400,000t. For the 2022 winter cropping year, ABARES is forecasting a national lentil crop of more than 840,000t.

While Australia is now the world’s second-largest exporter of lentils, shipping more than 95 per cent of production overseas, mainly in containers, Canada remains the largest producer and exporter. In 2020, Australia exported US$373 million of lentils, 13.3 per cent of the world lentil trade. Canada dominated the scene, exporting nearly 59 per cent of global trade.

However, efforts to expand lentil growing in Australia have often been stymied by low yields as the crop has been tried in regions less suited to the medium, winter-rainfall commercial varieties currently on the market, leading to overall national yields ‘flatlining’ at about 1.2t/ha for the past 15 years.

Agriculture Victoria researcher Dr Garry Rosewarne, who leads Australia’s lentil program at Horsham, says growers are now pushing the latest expansion in lentil production, driven by the attraction of high prices, lentils’ export potential, ease of storage and hardiness compared to other pulses.

Heat chambers in lentil trial plots where lentils’ ability to cope with high temperatures is being tested. Photo: Sukhjiwan Kaur

“Pulse prices always fluctuate more than wheat, but lentils tend to average around $600 to $700/t – and often higher – which in high-yielding southern growing areas with medium rainfall and alkaline soils, from the Eyre Peninsula through to the Wimmera, makes them a very attractive crop,” Dr Rosewarne says.

“They have become much more than just another legume to grow in a crop rotation to put nitrogen back into the soil so you can grow good cereal crops. Lentils are where the money is and we now have some farmers growing them year on year as their main crop.”

Dr Rosewarne says the challenge is now to extend the regions where lentils can be grown – without sacrificing yield – to drier and hotter parts of Australia such as Victoria’s Mallee, northern NSW and WA’s wheatbelt.

He is hopeful that seed stock originally brought into Australia from hot and dry Syria will hold the genes and traits that, with the new burst of GRDC-invested accelerated selection and breeding, will yield varieties better suited to parts of Australia with annual rainfall below 350 millimetres and temperatures exceeding 35°C during the crop’s winter–spring growing season.

Acid-tolerant varieties

Varieties that grow well in the acidic soils of NSW and WA are also part of the next quest.

“Breeders have done a great job in getting high-value agronomic traits such as taller and stronger plants, frost tolerance, disease resistance and now broadleaf herbicide tolerance embedded in new lentil varieties. Now we have to focus on extending the different soil and geographical regions where they can be grown,” Dr Rosewarne says.

“We have got new varieties that grow really well in alkaline soils and at a rainfall between 350 to 500mm, and now that you can knock out broadleaf weed competition six to eight weeks after sowing, yields have jumped. PBA Hurricane XT, PBA Hallmark XT, PBA Kelpie XT and PBA Highland XT varieties now dominate.

“The challenge is to keep those desirable traits and to find varieties that can grow with less rain and in the more acidic sandy soils such as you find right across the main WA wheatbelt (with the exception of Esperance), in the acidic soils of the NSW southern slopes around Wagga, and in the hotter, drier areas of northern and central NSW and the Mallee.

“These are our major wheatbelts and lentils should be able to be grown there too. We think we can do this through a breeding approach leading to improved germplasm that is more acid tolerant, with new varieties potentially following a few years later.”

Current lentil varieties only grow well in soils with a pH above 6.0, although optimal conditions are alkaline soils with a pH of 7.0 to 7.5.

Dr Rosewarne says lentil varieties that can grow well in naturally acidic soils of 5.0 to 5.5 pH would open up a great deal of cropping land in WA for lentil rotations, where low-value lupins for animal consumption are currently the only legume option.

But there are also cropping regions in NSW where continuous cropping for 50 years has induced subsoils to turn acidic 10 to 15 centimetres below ground level – known as the ‘acid throttle’ – depressing wheat yields and raising available manganese and aluminium levels to a point where they are toxic to plant growth.

“We are trying to pull that apart and understand what is really going on in the field, so we can then replicate that in our glasshouses when we are making breeding crosses, and in our glasshouses where we are making hydroponic seedling assays, and speed up the selection of acid-tolerant germplasm,” Dr Rosewarne says.

Heat tolerance breeding

In conjunction with the acidic soil project, Agriculture Victoria researcher Dr Sukhjiwan Kaur is focusing on breeding new lentil varieties that can be grown in hotter and drier regions of Australia such as northern NSW, WA and the Mallee.

The project will start by evaluating the heat tolerance of existing commercial lentil varieties. It will then assess other breeding material, as well as seed material held in the Australian Grains Genebank (AGG) in Horsham, for heat sensitivity traits, especially lentil germplasm and seeds that have come from drier and hotter regions around the world.

To speed up the selection program, Dr Kaur says, lentil lines that are identified as potentially the most heat and drought-tolerant will then be grown simultaneously in field trials and evaluated in glasshouses using temperature-controlled heat chambers before entering the genomic-assisted breeding pipeline.

Paddock trial sites have already been selected in hotter potential lentil cropping areas including at Curyo near Hopetoun in Victoria’s Mallee (some lentils are grown here already), Narrabri in northern NSW and Merredin in WA’s wheatbelt. Field trials will also be conducted at Horsham.

Dr Kaur says about 500 promising diverse lentil lines have already been selected from the national lentil breeding program, as well as the AGG, and will be screened each year for the next four years at Victorian sites to identify the best tolerance. Of these, 200 lines will also be grown at Narrabri and Merredin.

New lentil varieties could be grown as a cash crop or as legume rotation in much wider and more extensive parts of Australia.

During the four years these lentil lines or strains will be repeatedly sown and harvested, with the most promising, heat-tolerant candidates progressively identified. Validation of this field selection work will be extended to another 16 sites across Australia.

At the same time, Dr Kaur says, the lines identified as the most heat-tolerant will be crossed in an accelerated genomic-assisted breeding program, to speed up generational turnover time and the eventual development of new commercial varieties.

“We hope to be able to identify a set of lentil lines that can cope with temperatures at least five degrees above those that can be tolerated by current lentil varieties,” Dr Kaur says. “That means being able to tolerate temperatures above 35°C in that October–November period when crops are in their critical reproductive phase and setting seed.

“If we can do that and preserve yield, it would mean new lentil varieties could be grown as a cash crop or as legume rotation in much wider and more extensive parts of Australia, with their benefits available to many more grain growers.”

The big picture behind the urgent quest to expand lentil production in Australia is that, unlike faba beans where major export markets are limited to Egypt and the Middle East, lentils are in continuing high demand globally, especially from India, Pakistan and Bangladesh.

Dr Rosewarne believes lentils will also play a major role as the planet switches to eating less meat and more plant protein. “It is much more sustainable agriculture than producing livestock,” he says. “And all legumes are part of the regenerative cycle where they replenish the soil, replace synthetic fertiliser and allow cereal crops to continue to be grown.”

More information: Dr Garry Rosewarne, garry.rosewarne@agriculture.vic.gov.au; Dr Sukhjiwan Kaur sukhjiwan.kaur@agriculture.vic.gov.au