Significant differences between productivity and profitability of break crop options have been highlighted in Mallee Sustainable Farming’s SAGIT-funded project, ‘Adopting profitable crop sequences in the SA Mallee’, with high-value legumes proving their ability to offer farmers considerable benefits for diversity over continuous wheat.
So far lentils, field peas and vetch have proven to be the most productive crop options, with the quickest maturity, good yields and solid returns, though there were considerable variations in results between soil types.
With very little information available to support break crop selection, and Mallee growers looking to increase the proportion and diversity of broadleaf crops in their paddock rotations, trial sites were established in 2015 on contrasting soil types within a paddock at Loxton and Waikerie.
These sites represent the range of soil types that farmers manage in the northern SA Mallee, and include sands, sandy loams, red loams and shallow limestone soils.
MSF agronomist Michael Moodie says the three-year project aims to provide a cache of information for growers to successfully diversify into legume break crops in low-rainfall areas
Each site had nine different broadleaf crop options replicated four times, with treatments managed independently to ensure they had every opportunity to reach their potential. Agronomic management differences included herbicide choice, fertilizer rates and fungicide and pesticide applications.
Crops were sown in April (Loxton) and May (Waikerie) in 2015. All plots received 100kg/ha of single superphosphate banded below the seed and legumes were inoculated just before seeding with specific Rhizobian strain using a peat inoculant. Pre-emergence herbicide packages and rates were specific for each treatment and soil type.
Crop performance was assessed by measuring peak crop biomass and grain yield and harvesting took place in late October to mid-November to ensure that grain yield was measured soon after crops matured.
Gross margins were calculated for each treatment using the Gross Margin Guide, with January 2016 grain prices used to undertake the economic analysis. This was replicated the following year.
In 2016 the sites were sown soon after the break, Loxton on May 27 and Waikerie three days later. With extremely kind spring conditions, abundant moisture and a cool finish, grain yields across all crops were exceptional.
Field peas were the most productive crop grown across all soil types, averaging 2.9 tonnes per hectare, followed by vetch (2.2t/ha), narrow leaf lupin (2.1t/ha) and lentils (2.1t/ha) at the four trial sites. Faba beans yielded just under 2t/ha while both chickpea treatments yielded about 1.5t/ha (Kabuli 1.5t/ha, Desi 1.8t/ha). Canola and Albus lupins averaged less than 1.5t/ha.
High value crops, such as Kabuli chickpeas, produced high gross margins of about $2000 per hectare. Lentils also had an average gross margin of more than $1000/ha across the four trial sites.
Chickpeas were the most profitable crop across the four sites in 2016, with high prices of $1500/t, with Desi having an average gross margin of $2037 and Kabuli $1759.
Mr Moodie said the trial results in 2017 would confirm what could be achieved, in terms of productivity and profitability, and demonstrate the benefits of having a high level of diversity in cropping sequences.
“The high gross margins that have resulted from pulse crops, such as lentils and chickpeas, has been a standout result of the trials, and in 2017 it looks like chickpeas have again achieved high profits while the other break crop options have struggled,” he said.
“The trial makes a compelling case for increased crop diversity on Mallee farms. While field peas, lentils and vetch are consistently the highest yielding options, the potential for yield doesn’t always reflect potential for profit.
“High prices for lentils and chickpeas have made these crops profitable options for Mallee farmers in recent seasons where they might be able to yield a little less and still come out on top.”
Mr Moodie said the next step would be to refine the data to give farmers core information for better crop choice for specific combinations of soil types.