Take home messages

• Pulse crops have been demonstrated to be a profitable (and sometimes, an extremely profitable) enterprise across seasons and soils types in the low rainfall Mallee.
• While pulses are becoming an important component of Mallee farming systems, we still have a lot to learn about their agronomy and management on deep sands.
• Pulse crops have been shown to fix up to 300kg/ha of nitrogen in a Mallee environment, however farmers need to be aware that half of this nitrogen is removed in the pulse grain.

Background

Mallee farmers are now reaping the benefits that pulse crops add to productive and profitable farming systems. Pulses are now widely grown in ‘non-traditional’ regions such as the Mallee, not only due to the substantial ‘break benefits’ that they provide, but also as they have been shown to be profitable (and sometimes, an extremely profitable) enterprises in their own right. To support the expansion of the pulse growing industry in the Mallee, Agriculture Victoria (Ag Vic), Mallee Sustainable Farming and SARDI are currently conducting research and development projects aimed at improving pulse crop selection and agronomy in the low rainfall Mallee region.

Method

Southern Pulse Agronomy (SPA) is a collaborative research program across South Australia and Victoria led by Ag Vic and supported by investment by GRDC, Ag Vic, and SARDI. The program aims to deliver information on the agronomic implications of new traits in breeding lines and new varieties of pulses (lentil, chickpea, faba bean, lupin and field pea) within modern farming systems. Specifically within the Mallee of Victoria, two sites are now functional investigating a range of agronomic issues encompassing the four key topics of herbicide tolerance, disease management, canopy management (e.g. sow time, density, growth regulants) and harvest quality. Recent results from these sites are highlighted within this paper to demonstrate the potential of pulses to produce profitable yields and contribute significant farming system benefits.

Mallee Sustainable Farming Inc, with funding from South Australian Grains Industry Trust (SAGIT), commenced a three-year project in 2015 to compare broadleaved break crop performance across four soil types in the northern Mallee of South Australia (SA). The aim of these trials is to provide growers with information on the relative productivity of broadleaved grain crops in this low rainfall Mallee region. Trials were implemented to compare break crop productivity and profitability on major soil types in the northern South Australian Mallee. Trials were established at Waikerie and Loxton with two trials implemented at each site on contrasting soil types. At the Waikerie site, one trial was located on a sandy loam and the other on a shallow heavier soil with limestone while at the Loxton site, trials were located on either a red loam or a deep sand. The broadleaved crops represented in the trials are field pea, vetch, chickpea, lentil, lupin and canola. Productivity of the crops was assessed through biomass and grain yield while gross margins (GM) were calculated for each treatment using the Rural Solutions Farm Gross Margin and Enterprise Planning Guide (Farm Gross Margin Guide 2017).

Results and discussion

Can money be made with growing legumes in Mallee conditions

MSF Break Crop Comparison Trials

Trials in the Northern South Australian Mallee have demonstrated the potential for pulse crops to be profitable across two very contrasting seasons (Figure 1). In 2015, growing season rainfall (GSR) was below average (approximately 140mm) with a hot, dry finish to the season. In contrast, sites received 250 mm GSR in 2016 with 100 mm falling in September. Figure 1 shows the exceptional GMs that were achieved by pulse crops with lentils, vetch, field pea, chickpea and faba bean each achieving a GM of greater than $1000/ha on at least one soil type in the past two seasons. Lentils have been the most profitable of crop choice across soils types with an average GM of $820/ha over the two seasons. Vetch, field pea, chickpea and faba beans all had average GMs of $400 to $600/ha. The average GM of lupins and canola was $200 to $250/ha. Canola, lupins, chickpea and field pea produced negative GM (losses) on one constrained stony soil type in Waikerie in 2015, however all other crop x soil type x season combinations produced positive GMs. This should provide Mallee farmers with confidence that broadleaved crops can be a profitable paddock option.

Figure 1. Distribution of gross margins for broadleaved grain crops grown across four Mallee soil types in the South Australian in 2015 and 2016. Gross margins were calculated using five year average stated in the 2017 Rural Solution Gross Margin Guide.

SPA Mallee Trial Sites Estimated Pulse Profitability

Based on the average for pulses at the Curyo and Ouyen trial sites, all pulse crops were profitable in all years except 2015, where a slight loss was recorded at Curyo for both beans and chickpeas and at Ouyen for chickpeas. It is important to note that these figures incorporate all varieties and agronomic treatments at the trial sites, so the best varieties and agronomic treatments were still profitable. The high consistent potential returns from lentils are obviously a key driver for the expansion we are now seeing in lentils throughout the Mallee. These figures do not take into account the whole farming system economic benefits of a pulse from improved weed and disease management and the input of fixed nitrogen (N), which is discussed in the following sections within the paper.

Growing lentils on sands

Lentils are becoming an increasing popular crop choice in the Mallee environment. However they remain a challenging crop to grow across the entire paddock, especially on the deep sandy soils. This is reinforced by data from Loxton in 2016 where lentils had the greatest yield variability between the deep sand and the loam soil (Figure 2). Grain yield of lentils growing on sand were approximately 30% of the yield achieved on the nearby loam soils type. In contrast, lupins yielded approximately 1t/ha more the than lentils and lupin yields on the sand were approximately 70% of what was achieved on the loam soils type.

With pulses (especially lentils) in their infancy as an industry in the low rainfall Mallee region, extensive research is required to support best practice agronomy and management, particularly on sandy soils. Issues that need to be tackled for growing pulses on sandy soils include herbicide use, nutrition and inoculation, establishment and seeding systems.

Figure 2. Mean and range of grain yield for grain pulse crops grown on the deep sand (low yielding) and loam (high yielding) soil types at Loxton in 2016

Results at the Ouyen site in 2016 highlighted the potential differential ranking of varieties in a sandier soil (Figure 3). It was notable that PBA HurricaneXT was the highest yielding of the released varieties, similar to PBA Ace and PBA Jumbo. This may indicate differential tolerance to soil types as the soil was substantially sandier than at Curyo and no group B chemicals had been used at that site for several years. It has been observed in industry that PBA HurricaneXT appears to perform better than other varieties over sand hills. Further work is planned to investigate potential adaptation.

Figure 3. Grain yield of lentil varieties and breeding lines sown at two sowing dates at Curyo and one date at Ouyen (grain yield only as no disease present) in 2016.

Nitrogen fixed by legumes

Analysis of nitrogen (N₂) fixation by pulse crops growing in the northern Mallee showed that there is variation between crop species for the amount of N₂ fixed. Figure 4 shows that vetch, faba bean and lupin fixed the highest amount of nitrogen with 18 to 20kg N fixed/t dry matter (DM) while field pea and lentil fix 15 to 16kg N/t DM (Moodie et al, 2016).  Chickpeas are the poorest N fixers with 10kg N/t DM, however half of N fixed by chickpea is in the plant roots while other pulse species fix approximately one-third of the N below ground (Moodie et al, 2016).

Figure 4. Mean N₂ fixation in grain legume crop biomass in Mallee trials from 2013-2015 (Data adapted from Moodie et al. 2016).

The estimates of N₂ in the Mallee environment were applied to data from 2015 and 2016 for the Curyo and Ouyen SPA trial sites. Analysis compared total fixed N inputs (accounting for both shoot and root N fixation) to net fixed N accounting for N removed through grain yield (Table 3). The root factors and grain N% used in the analysis are reported in Moodie et al 2016. In 2015, all pulse crops fixed between 50 to 100kg N/ha with the exception of chickpea which fixed less than 50kg N/ha. However N fixation by pulse crops was much higher in 2016 with 100 to 300kg N/ha fixed across both sites. The exception was faba beans which is estimated to have fixed over 450kg N/ha at Curyo in 2016 (Figure 5). Across both seasons, net inputs of fixed N were approximately 50% of the total N fixed, showing that while large quantities of N may be fixed, N removal through grain yields is also high.

Figure 5. Relationship between total N fixed (shoot + root) and net inputs of fixed N following grain harvest for pulse crops grown at Curyo and Ouyen in 2015 and 2016 using estimates mean N₂ fixation, roots factors and grain N % reported in Moodie et al (2016).

Future Traits

Herbicide tolerances

Building on the success of previous lentil research by SPA and PBA which focused on improving and understanding Group B herbicide tolerance in lentil, a SARDI pre-breeding project developed Group B tolerant faba bean and Group C tolerant lentil germplasm. Previous agronomic field trials in SA and Vic in 2014 and 2015 confirmed faba bean germplasm lines with tolerance to a range of Imidazole (Imi) chemistries. In 2016, a trial with an advanced herbicide tolerant (HT) breeding line, the best HT germplasm line from the previous experiments, the faba bean variety Nura and the HT lentil variety PBA Hurricane XT was held at Rupanyup. This trial again demonstrated the high level of Imi tolerance in the HT germplasm line and also in the advanced breeding line with only minimal crop damage (Table 4) and no significant yield loss recorded to a range of Group B herbicides (not shown). Research continues in 2017 with trials at Ouyen and Rupanyup investigating tolerance on different soil types and rainfall zones.