Background

Lentil is a superior pulse food often attracting a premium price over other pulse crops. Unfortunately, the current perception of many agronomists and growers is that the crop is not adapted to our acidic soils, it is too short in height, too susceptible to weed competition and can be responsible for rapid build-up of weed seed banks. Most pulses (and their associated symbiotic rhizobia) prefer neutral to alkaline soils. Lentil growth, development and rhizobia survival can be affected when soil pH_Ca drops below 5.0. For these reasons, very few lentils have been grown in southern NSW - fewer than 1000ha each year. There are currently no local management guides or lentil section in the ‘NSW DPI Winter Crop Variety Sowing Guide’ (WCVSG). Historically, very little local agronomic research has been conducted into the crop in this region.

Our research at Wagga Wagga challenges these perceptions and aims to establish a viable industry in this region. Lentil varieties have vastly improved over the past decade due to breeding efforts by Pulse Breeding Australia (PBA). New varieties with improved vigour, height, disease resistance, pod-shatter resistance and yield are now available. To compliment these new varieties, agronomic management guidelines are being developed specifically for southern NSW soils and environments.

Research into the specific agronomic management of sowing time and seeding rate is increasing the success of lentil crops. Furthermore, growers routinely monitor their soils for pH and regularly incorporate lime to maintain base pH above 5.0. Canola production has been the driver behind these liming programs, providing flow-on benefits to pulses. This new generation of varieties, agronomic management and technical support has generated renewed interest in the crop in southern NSW and areas are expanding.

Results and discussion

Sowing time

Sowing date is one of the most critical management factors and determinants of lentil growth, production, yield and profit in southern NSW. Results from 2013, 2014 and 2015 agronomy trials and anecdotal evidence from growers and from production in other states indicate the optimum time to sow lentils in southern NSW is:

• Late April through to mid-May in the western cropping region (later than lupin and faba bean, but earlier than field pea)
• Early to late May (7–10 days later than western region) in the eastern cropping region.

Sowing beyond these dates severely compromises growth, production and yield. In our trials, delays of 10-20 days beyond these sowing windows severely reduced yield by 20-40 per cent (Figure 1), largely due to the increasing frequencies of quick dry finishes to the season over the past decade. Sowing earlier than these dates encourages disease, lodging, loss of seed quality and more aggressive weed growth in a crop already branded as a poor competitor.

Figure 1: Grain yield (t/ha) of six lentil varieties at two sowing times (May 18 and June 21) at Yenda in southern NSW, 2013.

Varieties

Variety selection should be based on grain yield, cotyledon colour and seed size. Current commercial varieties have either red or yellow cotyledons, and are then further divided into small, medium or large seeded (Table 1). The crop is marketed according to these criteria, with overriding quality factors such as seed staining, splitting and impurities.

Table 1: Lentil varieties are categorised and marketed according to seed colour and seed size. The last three columns present average lentil seed sizes from agronomy trials in 2013 and 2014.

Analysis of long-term trial data shows PBA Jumbo 2, PBA Greenfield and PBA Ace to be the best adapted, and highest yielding varieties in both the eastern, higher rainfall region of Wagga Wagga and the western, historically lower rainfall region of Yenda (Figure 2). Yields at Wagga Wagga were on average 20 per cent higher than Yenda (1.56t/ha compared with 1.31t/ha). Results for the new herbicide resistance variety PBA Hurricane were also encouraging.

Figure 2: Long-term (2010–14) grain yield comparisons of commercial lentil varieties, Wagga Wagga and Yenda.

Sowing depth and herbicide sensitivity

Lentil has excellent seedling vigour making it one of the quickest pulses to emerge and establish. Therefore, lentil seeds can be sown deeper (four to six cm) into safer zones below herbicide residues if present. Care should be taken when applying and incorporating herbicides on acidic, light textured soils as some herbicides can be more active and mobile in these situations. Under these conditions it is advisable to apply herbicides pre-sowing, use lower herbicide rates, and sow seed deeper below the herbicide band.

Seeding rates

Recommended target plant densities for lentil are 110-130 plant/m² (see ‘Southern lentil best management practices training manual’, Pulse Australia, 2015). Therefore, seeding rates are adjusted according to seed size and germination. This approximates to 45-55kg/ha for small seeded varieties (e.g. Nipper and PBA Hurricane), 55-70kg/ha for medium sized varieties (eg: PBA Ace) and 75-90kg/ha for large seeded varieties (eg: PBA Jumbo 2 and PBA Giant).

Under less favourable conditions such as later sowing, marginal sowing moisture or poor seasons, increase seeding rates by 10-20 per cent to stimulate better canopy closure, improved growth and higher grain yield.

Herbicide-tolerant lentil varieties

PBA Herald XT and PBA Hurricane XT introduce tolerance to the Group B herbicide imazethapyr (eg: Spinnaker® and Belta®), thereby widening weed control options in lentil. This is particularly relevant in a crop with only a narrow range of registered herbicides and already reputed as a poor competitor with weeds. They also have improved tolerance to flumetsulam (eg: Broadstrike®) as well as improved tolerance to residuals of some sulfonylurea (eg: Glean® and Logran®) and imidazolinone herbicides (eg: Raptor®). This provides some reassurance to lentil growers that problems of herbicide residues from previous cropping can be avoided.

Investigations at Wagga Wagga in 2014 confirm PBA Hurricane XT, PBA Herald XT and other breeding lines have excellent tolerance to imazethapyr, even when rates are increased to four times the recommended rate (Figure 3). PBA Hurricane was the best adapted of the commercial varieties, producing more biomass and grain yield (Figures 3). These results demonstrate how sensitive the two controls PBA Ace and PBA Jumbo2 are to imazethapyr, losing 70-80 per cent of their yield.

It is very important that product label rates, plant-back periods for subsequent crops, and directions for use are adhered to when using these herbicides.

Figure 3: IMI-tolerant variety trial grain yield of four commercial and a selection of breeding lines when treated with ‘Plus’ and ‘Minus’ 400g/ha Belta® 700 WG (700g/kg Imazethapyr) on June 22, Wagga Wagga, 2014 (Trial sown on May 8, 2014).

Conclusion

Recent research in southern NSW shows that lentil can be successfully grown with good agronomic planning and management. Careful consideration must be given to variety selection, paddock selection, time of sowing, harvest timing and market opportunities. Further research is required to evaluate new varieties and improve agronomic guidelines across southern NSW.

Acknowledgement

Funding for this work was provided through the GRDC Project DAV00113 and DAV00119, and their support gratefully acknowledged.

Contact details

Mark Richards
NSW Department of Primary Industries (DPI)
Wagga Wagga Agricultural Institute 
Pine Gully Road, Wagga Wagga NSW 2650
02 6938 18831
mark.richards@dpi.nsw.gov.au

NSW DPI
Pine Gully Road, Wagga Wagga NSW 2650
02 6938 1814
eric.armstrong@dpi.nsw.gov.au

Luke Gaynor
NSW DPI
Pine Gully Road Wagga Wagga NSW 2650
02 6938 1657
luke.gaynor@dpi.nsw.gov.au

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