Impact of row spacing and populations on chickpeas

Take home message

• Changes in agronomy can affect yield of chickpeas.
• In general increasing row spacing may decrease yield of chickpea varieties, even in a dry season.
• Small plot yields of 4.7t/ha achieved.
• Amount of nitrogen fixed reduces with wider row spacing.
• Trials being repeated in 2014 to confirm findings.

Background and aims

Despite the potential environmental and economic benefits, the adoption of winter and summer pulse crops in the Queensland Grains Region is around 8% and 4% of total cropping area respectively, much less than what is required to keep grain cropping systems profitable in the long term.  To increase the share of pulses in the total cropping area, strategies are required to enable growers to more consistently realise the potential productivity and profitability of pulse cultivars in their farming systems.

Winter pulses (chickpea and fababean) currently comprise approximately 8% of total cropped area in the Queensland Grains Region although the adoption varies from 5 to 12% depending on the growing region. Chickpea (Cicer arietinum) is the most adapted winter pulse crop in the Queensland with the area expanding to historically high levels in 2010. Seasonal yields of chickpea ranged from 0.5t/ha to 2t/ha depending on the timing and severity of biotic and abiotic stresses during the growing season.  Although yields as high as 2.5t/ha have been achieved in varietal evaluation trials, the average yield during the 2008 – 2011 was approximately 1.2t/ha in the focus regions included in this project (Source: ABS statistics), suggesting a significant potential to increase productivity. A modest 10% increase in yield would result in a $20 to $25 increase in gross margin (based on a $200/ha gross margin). Over a winter pulse area of 125,000 ha, the increase in crop production would be valued at $2.5 to $3 million per annum.  

Although the area sown to winter pulses in Queensland has increased over the last three years, there have been many challenges for growers with erratic seasonal conditions and a range of disease pressures on yield and quality. Growers’ attitude to pulse crops is also influenced by forecast prices relative to other cropping options including cotton and experiences from the previous season. The area of winter pulses in the region needs to be stabilised and the reliability of achieving seasonal yield potential improved.

The Pulse Agronomy project has consulted widely within the pulse industry to determine the priorities to be investigated throughout the term of the project.

Dalby chickpea trial winter 2013

The trial design was based on genotype (3 varieties Hatrick, Boundary and CICA0912 an advanced breeding line), three row spacing’s (0.25m, 0.50m and 1.00m) and 3 plant densities (20, 30 and 40 plants/m²).

The trial was planted on a well-structured, uniform deep to very deep, fine, self-mulching, cracking clay, endohypersodic, Black Vertosol (Waco). The plant water-holding capacity was 292mm (APSOIL v7.5) and available soil water at planting was 219mm to 1.5m.

Dalby trial results

Grain yield

In general, high to very high yields were obtained at this site and significant treatment affects from the agronomic treatments were achieved. The highest yielding treatment was almost 50% greater than the lowest-yielding treatment. The most consistently significant response was to row spacing and cultivar. An interaction between these treatments occurred (Table 1). There was no significant difference between any of the cultivars at the 0.25m spacing.   There were also no significant yield differences due to plant populations.

The highest yields occurred with the 0.25m row spacing, in interaction with cultivars (Table 1) and as a main effect averaged across all other treatments (Table 2).

CICA0912 was the highest yielding cultivar at all row-spacing’s and averaged across all other treatments (Table 3).

Table 1. Grain yield at Dalby – cultivar x row spacing

P<0.005, LSD = 0.3984

Table 2. Grain yield and harvest index, Dalby – row spacing, all varieties

Grain yield: P < 0.001,    LSD = 0.1375
Harvest index: P < 0.04,    LSD = 0.037

Table 3. Effect of cultivar on yield, Dalby

Grain yield: P < 0.03,    LSD  = 0.4007

Water use efficiency

Water use efficiency is a valuable measure of the potential suitability of a crop in a farming system. In this trial, very high water use efficiencies were achieved, approaching those generally accepted as satisfactory for cereal crops. Values for chickpeas are usually in the range of 7 to 8 kg/ha/mm water used. Narrow row-spacing produced the highest WUE and CICA0912 produced significantly great WUE than the other cultivars (Table 4).  On 0.25m spacing, CICA0912 produced the greater WUE than the other cultivars. 

Table 4. Row spacing effect on water use efficiency on grain yield

WUE: P < 0.02,    LSD = 1.79

Billa Billa chickpea trial 2013

The trial site was 40km NE of Goondiwindi on a well-structured, uniform deep to very deep, fine, self-mulching, cracking clay, Endohypersodic, Grey Vertosol.  The plant water-holding capacity was 107mm (Yash Dang pers. comm.) and measured available soil water at planting was 104mm to 1.5m.

The same treatments as Dalby were used in this trial.

Billa Billa trial results

Grain yield

In general, the yields obtained at this site were higher than the surrounding commercial yields. Significant treatment affects from the agronomic treatments were achieved. Narrow row spacing increased the yield components. There was no significant difference between any of the cultivars across the treatments.  

The highest biomass and grain yields occurred with the 0.25m row spacing and as a main effect averaged across all other treatments (Table 5). Harvest index was greatest at the 0.25m row-spacing.

Plant population had no significant main effect or as an interaction.

Table 5. Effects of row-spacing on yield and harvest index

P<0.001, LSD=37.8               P<0.001, LSD=0.033

Water use efficiency

Again very high water use efficiencies were achieved in this trial, approaching those generally accepted as satisfactory for cereal crops. Values for chickpeas are usually in the range of 7 to 8 kg/ha/mm water used. Narrow row spacing’s (0.25 and 0.5m) produced the higher WUE compared to the 1m spacing (Table 6). 

Table 6. Effect of row spacing on water use efficiency on grain yield.

P<0.001, LSD=0.024

Nitrogen fixation

There were no differences in N fixation amongst varieties but row spacing significantly decreased %Ndfa (nitrogen derived from the atmosphere) and total amount of N fixed, particularly at the Dalby site (Table 7).

The net N balance for each of the sites also showed a significant impact of row spacing and of the site.  Up to 59 kg N/ha remained at the Dalby site when chickpeas were grown on 0.25m rows but only 23 kg N/ha from the 1.0 m row spacing.  At Goondiwindi, the net N balance ranged from 6 down to -6.4 kg N/ha as row spacing increased from 0.25m to 1.0m.   Our values were similar to those measured by Schwenke et al. (1998) who found lower N fixation in chickpeas in the drier year (1994) of their survey of commercial crops in northern NSW.  As a crops’ demand for N increased so did the N fixation by that crop as seen at our Dalby trial grown under better seasonal conditions.  However, the row spacing effect cannot simply be explained by higher plant N demand as all crops were at the same plant population density of 30 plants/m².  On-going trial work in 2014 will examine links of N fixation with changes in other agronomic factors (eg. soil temperatures and water use efficiencies) due to different row spacing.

Table 7. Reduction in N fixation and total amount of N fixed in chickpea (mean across 3 genotypes) as row spacing in the field increases

Summary and conclusion

Narrow row (0.25m) gave significantly higher yields, harvest index, water use efficiency and total N fixed.

Row-spacing of 0.5m gave the same yield as 0.25m for CICA0912 at Dalby. Boundary and Hatrick yielded the same as CICA0912 at Dalby on 0.25m spacing but there was no interaction with cultivar at Goondiwindi.

There was no significant effect of plant density at either site.

CICA0912 gave 10% higher yield than Boundary and Hatrick (Dalby only).

CICA0912 was more suited than other cultivars to 1m row-spacing.

Trials are continuing in 2014 to confirm the trends seen in 2013, following harvest and analysis of results a firm recommendation can be made in relation to current varieties and management strategies.

References

Schwenke GD, Peoples MB, Turner GL and Herridge DF (1998) Does nitrogen fixation of commercial, dryland chickpea and faba bean crops in north-west New South Wales maintain or enhance soil nitrogen? Australian Journal of Experimental Agriculture 38, 61-70.

Acknowledgements

Many thanks to supporters of the trials from Stephen Krosch, James McLean, trial co-operators Glenn Milne and the Woods Family.

Contact details

Kerry McKenzie

Department of Agriculture, Fisheries and Forestry Queensland

Ph: 07 4688 1211

Email: kerry.mckenzie@daff.qld.gov.au