THE potential to dramatically increase chickpea yields by up to one tonne per hectare - through a simple change in row spacing - is set to deliver increased profit margins for Dalby, Queensland, grain grower Glenn Milne.
Mr Milne has been hosting a series of Pulse Agronomy trials, from which early data indicates that a move to 25-centimetre row spacings would significantly outperform the yields available on 1-metre rows.
And the trials have revealed higher levels of nitrogen fixation from the crops on narrow rows, delivering a further boost to subsequent cereal crops in Mr Milne’s rotation.
“Last year our average yield on that country where that trial was held was 3.1 tonnes a hectare – the trial maximum yield was up over 4 tonnes a hectare, so an extra tonne to the hectare is pure profit,” Mr Milne said.
“We were growing chickpeas on 30-inch or roughly 75-centimetre row spacings but because the trial showed there was a significantly higher yield on offer we have already halved our row spacings to 15 inches (37cm) – all we did was double plant them with our 30-inch planter to get our 15-inch row spacing.”
Mr Milne owns and leases a total of 600 hectares of highly fertile black soil country on the Jimbour Plain just north of Dalby, growing dryland sorghum, chickpeas, faba beans, mung beans, barley and wheat, as well as some irrigated cotton and corn.
As a former agronomist, he has been keen to host industry trials on his property to further improve his knowledge and compare his farm practices with new approaches.
The trials on his block are funded through the Grains Research and Development Corporation’s (GRDC) Queensland Pulse Agronomy Initiative, which involves collaboration between Department of Agriculture Fisheries and Forestry (DAFF) and the Queensland Alliance for Agriculture and Food Innovation (QAAFI).
The program is seeking to improve adoption of legumes within Queensland crop rotations by identifying measures which can both boost yields and improve the reliability of pulse crop performance.
The research is being led by DAFF senior extension agronomist Kerry McKenzie who said chickpeas traditionally only yield an average of 1.2t/ha in dryland broadacre conditions in Queensland, whereas the small-plot trials at Mr Milne’s property achieved 4.7t/ha using an advanced breeding line when planted at 0.25m and 0.5m row spacings.
Yields of 4.5t/ha and 4.4t/ha were also achieved using the commercially available varieties PBA HatTrick and PBA Boundary respectively, both on 0.25m spacings.
Mr McKenzie said the 2013 trial results were encouraging, but were still being validated through the second year of field testing currently underway.
“We can show a distinct yield advantage of narrowing up your rows. At 900kg per hectare difference between 1m and 25cm that’s straight up $300/ha benefit from reducing your row spacings,” Mr McKenzie said.
“There’s still some questions about going to narrower rows and about logistical questions such as how to handle stubble with narrower plantings, but the results so far have already got a lot of farmers thinking about how they might start reducing their row spacings.”
Mr Milne said the trials had revealed to him the true potential of chickpea crops in his environment.
“Our aim is to get up to that yield that the trial achieved and this year we’re hoping to get closer to that yield potential through narrowing up our row spacings,” he said.
“Although we haven’t yet got access to the new variety which was the highest yielding variety, the ones we’ve got available to us at the moment aren’t that far behind.”
The trials also revealed that narrow row spacings provided greater nitrogen fixation and the highest measurements for water use efficiency.
Up to 59 kg N/ha remained at the Dalby site when chickpeas were grown on 0.25m rows compared to only 23 kg N/ha from the 1m row spacing.
“Legumes are such an important part of our system – nitrogen fertiliser is our biggest cost and if we can get free nitrogen out of the air we can maximise our yields with our legumes,” Mr Milne said.
“Our performance history has shown that we’ve grown our best crops after a legume, particularly chickpeas. Our sorghum crops do exceptionally well after chickpeas.
“I think it’s a combination of adding that extra nitrogen but also the type of release of that nitrogen – it’s not a sudden hit, it seems to be metered out as it’s mineralised.”
Mr Milne does not plan to cut back on his current fertiliser applications, but rather use the extra nitrogen provided by chickpeas to provide the nutrient buffer required for crops to reach their full potential if sufficient in-crop rain falls during the growing season.
“We’re probably over-fertilising in dry years but we want that nitrogen there to ensure our crops reach their yield potential if it does rain.”
Mr Milne said inclusion of legumes in his rotation provided additional benefits in terms of rotating chemical groups for weed control.
“And we know weeds don’t like competition so the narrow row spacings should be a benefit there as well,” he said.
The trials found that plant population did not influence yields, but the 2014 trial work is testing lower populations of just 10 plants per square metre (the industry standard is between 20 and 30 plants/square metre) to determine how low farmers can go without impacting results.
Following the harvest of the 2014 trial plots and analysis of results, practice recommendations are expected to be made in relation to current varieties and management strategies.
