Irrigated pulse trials

Take home messages

• Drainage was the key to a successful trial.
• In 2017, pre-irrigation alone provided sufficient moisture to grow the crop successfully.
• In 2017, the addition of spring irrigations did not translate to improved yield or grain quality.
• In 2017 there was low disease pressure.
• Irrigated lentils and chickpeas could be quite profitable, assuming that the 2017 harvest prices are maintained.

Background

Growing irrigated chickpeas and lentils has potential financial rewards but their reputation for susceptibility to waterlogging and disease may make them a risky proposition. However, advances in irrigation technology and infrastructure may have reduced some of that risk. The Irrigated Cropping Council is attempting to test their performance with trials that have a combination of irrigation technologies, irrigation and fungicide strategies and variety evaluation.

Method

Trials consisting of four varieties of lentils and four varieties of chickpeas were sown at three locations – ICC Trial Block Kerang, (border check), Dhuragoon (near Moulamein, NSW, overhead spray) and Appin (subsurface drip ‘on the flat’). All sites were grey clays (vertosols) and each site had a combination of irrigation and fungicide strategies. Growing season rainfall at trial sites was 220mm (Figure 1).

Figure 1. Rainfall and irrigation (latter circled) at the trial sites during 2017.

Table 1. Irrigated pulse trial irrigation infrastructure and strategy.

Overlaid on each site were two fungicide strategies – strategic (applied only when disease pressure is expected to be high such as pre-irrigation or a rainfall event) or regular application every three weeks.

Table 2. Varieties tested, target population (plants/m²) and sowing rate (kg/ha) at each site.

Results and discussion

Border-check trial

The border-check trial was sown on 16 May following pre-irrigation (1.8ML/ha) on 8 April 2017. Terbyne Xtreme (1.0kg/ha) + Glyphosate (1.5 L/ha) + Goal (75 ml/ha) was used as a pre-emergent treatment. Thirty millimetres of rain fell shortly afterwards but did not affect establishment.

The fungicide program started on 21 July, with 1.5 kg/ha Mancozeb applied to all plots.

The ‘3 week’ treatments then occurred on 11 August, 31 August, 13 September, 29 September and 10 October using Chlorothalonil at 1.5L/ha – a total of six fungicide applications for the season.

The ‘strategic’ treatment was sprayed on 21 July, 31 August (onset of rain), 13 September (irrigation) and 10 October (onset of rain).

No disease was detected in any plots during the season.

The first spring irrigation (0.8ML/ha) occurred on 13 September in response to soil moisture probe data. At this stage, the first flowers were starting to appear on the lentils and chickpeas. The second spring irrigation (1.0ML/ha) occurred on 30 September.

The ‘pre-irrigation only’ treatment appeared quite dry in mid-September, with cracks starting to open up. However, the plants remained quite green until well into October.

After the first spring irrigation, which took nine hours at 6ML/day, there appeared to be little waterlogging damage to the plots.

The second spring irrigation (‘Full Irrigation’ treatment, 1.0 ML/ha) took six hours and resulted in some areas of yellowing plants, but the overall impression was that there was minimal damage.

Plots in the ‘pre-irrigation only’ trial began to hay off in late October, while the irrigated trials remained green.

Harvest occurred on 14 December 2017.

Results

Yield and grain quality

Yield data and grain quality for chickpeas and lentils is presented in Table 3. The fungicide strategy made no difference to either chickpea (p = 0.43) or lentil (p = 0.34) yields.

Table 3. Border check grain yields (t/ha) for chickpea and lentil with different irrigation strategy.

Seed size

Fungicide strategy made no significant difference to seed size (Table 4).

Table 4. Average seed size (g/100 seeds) for chickpea and lentil with different irrigation strategy.

Gross margin

Table 5 summarises the gross margins for the irrigated pulses using the assumptions:

• Prices: Kabuli $800/t, Desi $600/t, Red Lentils $550/t, Green Lentils $650/t
• Water cost $100/ML
• Autumn pre-irrigation used 1.8 ML/ha
• Four fungicide applications

Table 5. Gross margins for irrigated pulses on a pre-irrigation only or one spring irrigation strategy.

An excel-based Gross Margin calculator is available from ICC if you wish to calculate the gross margins of the irrigated pulses using your own scenario.

What does it mean?

Results indicate that irrigation was not detrimental to the performance of the pulses, however yield was not significantly improved by any spring irrigation. Bear in mind the soil profile was almost full at the end of August 2017. If this moisture reserve had not been in place, a yield response to spring irrigation may have been seen.

Seed size was not negatively affected by lack of spring irrigation, and in many cases, lack of irrigation resulted in small improvements in seed size.

2017 was a low disease pressure season which most likely contributed to the observation of little benefit from the more frequent fungicide strategy.

Gross margins (GM) can rapidly change with variations in price and yield. A GM calculator, be it a simple spreadsheet or a more comprehensive example like the Correct Crop Sequencing Decision Support Tool which can ‘price in’ commodity or water price fluctuations, can help irrigators test the viability of growing any irrigated crop.

Overhead sprays

An overhead spray trial similar to that conducted at the Trial Block (i.e. border-check trial) was sown on 1 June. Sowing was delayed due to the site being too wet following pre-irrigation (approximately 0.7ML/ha) and rain in mid-May.

Initial grass control was poor from using 500ml/ha clethodim on 21 July. Following confirmation of the poor result, a second attempt was made on 18 August using butroxydim at 180g/ha. Only partial control was achieved and the trial suffered from high ryegrass numbers.

The fungicide program started on 21 July 2017, with 1.5kg/ha Mancozeb applied to all plots.

The ‘3 week’ treatments then occurred on 9 August, 31 August, 19 September, 29 September and 10 October using Chlorothalonil at 1.5L/ha – a total of six fungicide applications for the season.

The ‘strategic’ treatment commenced on 21 July, with further applications on 31 August (onset of rain), 29 September (irrigation) and 10 October (onset of rain) – a total of four applications.

No disease was detected in any plots during the season.

Irrigation began in late August and the last ‘to flowering’ irrigation occurred on 29 September, with spring irrigation totally approximately 1.0ML/ha. The ‘Full’ treatment received an extra two irrigations or approximately 0.8ML/ha.

Areas of poor drainage became apparent in early September, with yellowing of the plants and reduced vigour.

The trial was harvested 15 December.

Results

Yield

Results indicated that the irrigation strategy did not affect the yield of either chickpea (p = 0.83) or lentil (p = 0.31).

Table 6 incorporates data from both the ‘up to flowering’ and ‘full’ irrigation treatments. Fungicide strategy did not have any effect on yields. Caution needs to be taken when making any conclusions from this data as yield data was highlyvariable (high cv% value).

Table 6. Overhead grain yields (t/ha) from the fungicide strategies

Seed size

Neither irrigation nor fungicide strategy made any difference to seed size (Table 7).

Table 7. Average seed size (g/100 seeds) for chickpea and lentil varieties.

What does it mean?

In summary, the results indicate that drainage is king. Despite smaller and more frequent irrigations, plant damage (yellowing and poor vigour) and death was much higher when compared to the border check trial due to the flat nature of the site.

Ryegrass competition was a factor in the poorer and variable plot yields.

2017 was a low disease pressure season which most likely contributed to the observation of little benefit from the more frequent fungicide strategy.

Sub-surface drip irrigation

The sub-surface drip irrigation trial was sown on 17 May 2017 following pre-irrigation (approximately 1.5ML/ha).

Terbyne Xtreme (1.0kg/ha) + Trifluralin (1.0L/haɸ) + Glyphosate (1.5L/ha) was used pre-sowing.
ɸRate listed is below the minimum label rate of 1.25L/ha. In commercial situations, label recommendations must be adhered to.

Establishment was below expectations at the site due to 30mm of rain that fell shortly after sowing, which resulted in waterlogged conditions, and then predation by mice. The chickpeas were especially targeted by the mice, which resulted in one replicate of the trial being resown on 19 June.

The fungicide program started on 20 July, with 1.5kg/ha Mancozeb applied to all plots.

The ‘3 week treatments then occurred on 11 August, 1 September, 22 September and 10 October using Chlorothalonil at 1.5L/ha – a total of five fungicide applications for the season.

The ‘strategic’ treatment was sprayed on 21 July, 1 September (onset of rain) and 10 October (onset of rain) for a total of three applications.

No disease was detected in any plots during the season.

The first spring irrigation occurred on 22 September, with the first flowers starting to appear. The soil became quite wet and although no water broke out on the surface the soil remained quite wet for several days.

After the first spring irrigation (approximately 1.0ML/ha), individual plants began to yellow and progressively die. The green lentils appeared to be most susceptible to the irrigation induced waterlogging. Plots with low establishment appeared to fare worse.

Harvest occurred on 6 December.

Results

The following results presented in Table 8 should be viewed with caution as the data was quite variable. Plots ranged from very few plants to reasonably well vegetated plots with random bare patches. Data from all irrigation and fungicide treatments has been consolidated into one data set.

Yield and seed size

Table 8. Grain yields (t/ha) and seed size (g/100 seeds) for chickpea and lentil varieties.

What does it mean?

In summary, the results indicate that drainage is king. The trial was sown onto ‘the flat’ rather than on beds. Prolonged waterlogging post-sowing and post-spring irrigation, saw poorer establishment and increased plant damage compared with the other trials. Poorly established plots appeared to suffer from higher plant death in spring which may be due to the lack of plants (i.e. poor establishment) and the subsequent low water use, which extended the period of waterlogging. Raised beds would have improved drainage and plant establishment, survival and vigour, and consequently crop yields.

The beneficial value of the fungicide treatments was compromised by the variable establishment of the plots.

Irrigation seemed to be detrimental, particularly to the green lentil variety, GiantA, with very few plots harvestable.

Conclusion

Drainage is king. Even though irrigation volumes were smaller and/or application duration was shorter in the overhead and subsurface drip systems, the key for success was drainage post irrigation or rainfall event. The flat layouts of the overhead and subsurface drip irrigation did not facilitate drainage and subsequently the pulses suffered waterlogging, resulting in poorer growth and plant survival.

If drainage is adequate, either by slope, soil texture or beds, then there is potential for chickpeas and lentils to be a profitable irrigated pulse crop.

The results from 2017 suggest spring irrigation at any stage did not improve yield or grain size. 2017 experienced well-above average rainfall in August, resulting in an almost full soil moisture profile coming into September. Without this soil moisture buffer, a different result may have been achieved from the ‘pre-irrigation only’ treatments.

Disease management will be crucial to achieving high yields.

Useful resources

Correct crop sequencing decision support tool

ICC Trial summary 2017

On farm trials website

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC — the authors would like to thank them for their continued support.

Thanks to Michael Gorey, Dhuragoon and Darren Sutherland, Appin, for hosting the trials.

Thanks to Rob Launder (PB Seeds) and Rob Christie (Seednet) for sourcing and supplying seed for the trials.

Contact details

Damian Jones
Irrigated Cropping Council
PO Box 549, Kerang 3579
0409 181 099
damian.jones@irrigatedcroppingcouncil.com.au
@Canola_Boy