Key points
- Deep ripping of deep Mallee sands improved chickpea, faba bean, field pea, lentil and vetch gross margins by more than $300 per hectare
- Undertake ripping with caution to minimise the risk of erosion and herbicide damage
Trials located on deep Mallee sands over the past three seasons – 2019 to 2021 – have demonstrated substantial increases in pulse crop yields in response to soil amelioration practices such as deep ripping.
Mallee soils are highly variable and the productivity of all pulses, except lupins, decreases dramatically on the deep sands of the dune-swale system, which make up 20 to 30 per cent of the region’s cropping soils. These soils have high penetration resistance within the top 50 centimetres of the profile, limiting root penetration and crop water uptake.
Deep sandy soils were ripped to 400 or 500 millimetres in summer before sowing pulse crops in South Australia at Lameroo in 2019 and 2020 and in Victoria at Kooloonong in 2019 and 2020, Speed in 2020 and Tempy in 2021. Chickpeas, faba beans, field peas, lentils, narrow-leaf lupins and vetch were sown at a minimum of three sites each.
The trials were conducted as part of GRDC’s investment in southern pulse agronomy through Agriculture Victoria, the South Australian Research and Development Institute (SARDI) and Frontier Farming Systems, with additional support from the Murraylands and Riverland Landscape Board in collaboration with Mallee Sustainable Farming.
Ripping benefits
Results demonstrated that chickpeas and faba beans were the most-responsive pulse crops, with an average yield increase of 210 per cent across all trial sites. Average lentil yields improved by 166 per cent, and field peas and vetch by about 100 per cent.
Gross margin analysis showed that the average yield response observed across the trial sites was highly profitable (Table 1). This is based on the average January price for each pulse crop (2020 to 2022) and includes an annualised cost of deep ripping of $40 per hectare.
Table 1: Average gross margins demonstrate the yield benefit to pulses of deep ripping on deep sands across six Mallee trial sites from 2019 to 2021. Calculations are based on the average January grain price from 2020 to 2022 for each pulse crop and the annualised cost of ripping of $40 per hectare.
Crop | Average yield benefit (t/ha) | Average grain price ($/t) | Gross margin benefit ($/ha) |
|---|---|---|---|
Chickpeas | 1.1 | $643 | $668 |
Field peas | 1.0 | $427 | $387 |
Faba beans | 0.9 | $449 | $364 |
Vetch | 0.7 | $533 | $333 |
Lentils | 0.5 | $703 | $312 |
Narrow-leaf lupins | 0.1 | $486 | $7 |
Source: Michael Moodie.
Chickpea gross margins were most improved at about $667/ha. Deep ripping also improved faba bean, field pea, lentil and vetch gross margins by more than $300/ha. Importantly, ripping reduced the financial risk of growing pulses by reducing the number of seasons with a negative gross margin.
In contrast to the other grain legumes, deep ripping provided no economic benefit to lupins in these trials. Lupins have a much-higher establishment risk than other pulses due to their requirement for shallow seed placement. They should not be sown in the first season post-amelioration as soft seedbeds can lead to deep seed placement, soil throw or slumping of furrow walls, resulting in poor establishment.
Subsequent cereal crops will benefit not only from the legacy effects of deep ripping, but also from the increased nitrogen fixation that results from improved pulse biomass.
Ripping considerations
While these trials have shown large productivity and profitability benefits, growers considering deep ripping must evaluate operational risks. For example, deep ripping before a pulse phase should be targeted to paddocks with high levels of residual stubble to ensure adequate ground cover is maintained and minimise erosion risk. Care also needs to be taken with pre-emergent herbicides to minimise risk of crop damage.
Trafficability of heavy machinery is also an issue that needs to be managed post-ripping. Rolling with heavy steel drum rollers is recommended to reconsolidate the surface and provide better flotation for the seeder and self-propelled sprayers.
More information: Michael Moodie, 0448 612 892, michael@frontierfarming.com.au; Dr Jason Brand, 0409 357 076, jason.brand@agriculture.vic.gov.au; Dr Penny Roberts, 0436 678 982, penny.roberts@sa.gov.au