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The integration of novel forage and grain systems in Southern Australia

Penny Roberts Craig and David Coventry

University of Adelaide, School of Agriculture, Food and Wine, Roseworthy Campus, South Australia 5371

Abstract

As part of a study into the development of novel forage systems for mixed farms in the higher rainfall areas, field experiments were conducted in 2007/2008 at Benayeo (Victoria) to evaluate the yield performance of pasture and grain intercrops. The intercrops were grown on double skip row arrangement and compared to the performance of the intercrop components grown as sole stands. The intercrop pasture species selected were summer active perennial species lucerne and chicory. The grain species used were wheat, lupins and canola. There were grain yield reductions as low as 8% when chicory was grown with canola and as high as 74% when lucerne was grown with lupins. The highest yield reductions were recorded with lucerne for each treatment with the most competitive crop species being canola and the least lupins. Dry matter yield of the pasture species were also affected in an intercropping situation with penalties between 20% and 80%. The lucerne dry matter yields had consistently higher reductions than chicory when grown with each of the crop species. Despite the yield penalties the results, when Land Equivalent Ration (LER) were calculated, showed that the intercrops using chicory as the pasture species consistently produced LER values of greater than 1, indicating that in this environment it was more productive to grow chicory and grain crops as an intercrop than as sole stands.

Key Words

Intercropping, companion cropping, chicory, lucerne

Introduction

The traditional grazing-dominant medium to higher rainfall (500 – 700mm) regions of southern Australia has in recent years had an increasing trend towards including more cropping in the system. This change is a result of the relatively higher returns from cropping compared with traditional grazing enterprises. With an annually based cropping component introduced into the system, there is the possibility that the amount of water used will be less compared to a continuous perennial-based system. This is important both environmentally and economically given an awareness that a continuous annual based system may not be sustainable in the long-term, associated with water recharge and environmental issues such as waterlogging, high watertables and salinity (Dear et al.2003). As a consequence there is ongoing work being done on incorporating perennial pastures, most commonly lucerne, into cropping systems as intercrop sequences (Harris et al. 2007). Intercropping is a system where two species are grown together either with or without distinct row arrangement. Intercropping may also allow for easy transfer either into or out of a cropping or pasture phase (Robertson et al. 2004). Importantly intercropping can also be more productive when compared to growing each of the intercrop species as sole stands. In this paper we report the use of novel crop/pasture intercropping systems arrangements, with the purpose of providing a continuous forage/grain supply to a farming system that is primarily livestock based.

Materials and Methods

The experiment was undertaken during the 2007/2008 growing season at Benayeo Victoria (Lat. 36°50' Long. 141°30'), 12km east of the South Australian and Victorian border. The soil type of the site is a duplex soil consisting of a sandy loam over clay, with a depth of about 30cm from soil surface to the clay layer. The long-term rainfall is 500mm, and the rainfall in 2007 at this site was 473.5mm with 308mm falling within the growing season (April – October). The experiment was a randomized block design with 4 replicates, with crop-pasture sequences started in both 2006 and 2007. The 2006 established treatments involved 6 intercrops; wheat and lucerne, lupins and lucerne, canola and lucerne, wheat and chicory, lupins and chicory, canola and chicory; and 5 sole crops of each of the component species. The site established in 2007 had lucerne and chicory intercrops with wheat plus sole stands of these components. The configuration of the intercrop was a double skip row. Grain and yield components were measured 10 days post desiccation of the pasture species (December 2007). Dry matter (DM) harvest of the forage components of the intercrops took place during the growing season of the grain crop as well as at intervals post-harvest until 2 weeks prior to the sowing of both sites again in 2008. The grain and forage yields were used to calculate the Land Equivalent Ratio (LER) following the method of Mead and Willey(1980).

Results and Discussion

In both first and second year pasture-intercrops there were grain and DM yield penalties compared to the sole treatments (Table 1 and 2). The grain yields were significantly different between sole grain crops and the lucerne intercrops; this varied from a reduction of 19% in the canola-lucerne intercrop to 74% in the lupin-lucerne intercrop. There were also variations in the yield reductions from wheat between the first year pasture lucerne (20%), and second year lucerne pasture (44%), first year chicory pasture (19%) and second year chicory pasture (42%), indicating that both lucerne and chicory are more competitive once established. Other studies with lucerne-wheat intercrops have shown similar, and higher, yield reductions of between 13-63% (Humphries et al. 2004), and in lucerne-barley of between 6-62% (Egan and Ransom,1996). Where chicory was the intercrop species there were also significant differences between the grain yield of the sole and intercrop treatments for wheat and lupins (Table 1), however the chicory intercrop had no affect on canola grain yield. For all crops there were lower yield penalties when the grain crop was grown with chicory compared with lucerne, this is shown most significantly with lupins, (chicory-lupins 48% and lucerne-lupins 74%) and canola (chicory-canola 8% and lucerne-canola 19%). These results suggest that lucerne when grown as an intercrop is more competitive for resources than chicory.

Table 1. Wheat, Lupin and Canola grain yields, 2007

Wheat Grain Yield t/ha (2nd year pasture) lsd = 0.71

Sole Wheat

Wheat-Lucerne

Wheat-Chicory

3.33

1.87

1.95

Wheat Grain Yield t/ha (1st year pasture) lsd = 0.24

Sole Wheat

Wheat Lucerne

Wheat Chicory

3.58

2.87

2.91

Lupin Grain Yield kg/ha (2nd year pasture) lsd = 0.32

Sole Lupin

Lupin-Lucerne

Lupin-Chicory

1.97

0.52

1.02

Canola Grain Yield kg/ha (2nd year pasture) lsd = 0.26

Sole Canola

Canola-Lucerne

Canola-Chicory

1.76

1.43

1.62

As with crop grain yields, there were also DM yield reductions when comparing the intercrop to the sole pastures (Table 2). The results show lucerne consistently had higher yield reductions in all grain crop combinations compared to the chicory. There were also higher pasture yield reduction in the establishment year of the pasture.

Table 2. Total Chicory and Lucerne DM yields from 2007/2008 and DM yield penalty when associated with intercrop

 

2007 (2nd year pasture)

2007 (1st year pasture)

Treatment

DM Yield (kg/ha)

Penalty (%)

DM Yield (kg/ha)

Penalty (%)

Sole Chicory

4783

  

6171

  

Sole Lucerne

6558

  

3826

  

Chicory-Wheat

2826

41%

1858

70%

Lucerne-Wheat

2238

66%

780

80%

Chicory-Lupins

3669

23%

    

Lucerne-Lupins

4070

38%

    

Chicory-Canola

778

84%

    

Lucerne-Canola

909

86%

    

An intercrop study by Harris et al. (2007) showed similar biomass yield reductions in lucerne of 71%. In the Harris et al. (2007) study, they found that while they were able to achieve increases in crop biomass by the addition of N after tillering, or lucerne suppression using a clopyralid spray, this did not result in increased grain yield. They suggested that rainfall was an important factor in influencing the yield of the intercrop. In our study soil moisture readings were taken in 2007 (results not shown) using TDR at depths of 0-15cm and 0-35cm. These preliminary results showed differences in soil water use in the different treatments, for example, with the chicory using less water during the winter-spring period particularly in the 0-15cm range. This suggests competition between the intercrop species for soil moisture might be responsible for some of the yield differences in the treatments.

While our study has shown significant yield reductions when growing pasture and grain crops as intercrops, importantly it has also shown that LER values of >1 can be consistently achieved (Table 3). With chicory as the intercrop pasture species, it produced LERs of >1, both as a first year and second year pasture. This suggests that in this environment it may be more valuable to grow chicory in an intercropping situation with wheat, lupins or canola than growing these component species as sole stands. However, whilst the LERs for lucerne are <1 (Table 3), they are still high (more than 0.88), and with further understanding of the constraints affecting crop yields the associated yield penalties may be reduced, resulting in higher LERs. In a study by Humphries et al. (2004), they achieved LER values of >1 where they used species selection and agronomic practices to improve the system. Where they overcropped with winter-dormant lucerne with wheat they achieved LER of >1 in 2 seasons at 2 different sites. The work also showed a positive response to a single application of N at sowing. There is also with lucerne benefits that can not be calculated in a LER, such as fixation of N2, which could reduce the fertilizer requirements for the companion grain crop.

Table 3. Land Equivalent Ratio (2007)

Treatment

2007 (2nd yr pasture)

2007 (1st yr pasture)

Wheat-Lucerne

0.89

0.99

Wheat-Chicory

1.18

1.11

Lupins-Lucerne

0.89

 

Lupins-Chicory

1.28

 

Canola-Lucerne

0.96

 

Canola-Chicory

1.10

 

Conclusion

The calculated LER values of >1 for chicory indicate substantial productivity benefits of an intercropping system. The grain and pasture yield penalties described in this and previous studies suggest this is caused by competition of the intercrop species for resource and that further investigation into these interactions may provide techniques that can be adopted to reduce the yield penalties of intercrops. This paper has focused on the yield results from intercropping however it is only one component that show the potential benefit of this system, which also includes management of soil water, weed control and nutritional requirements of the component species. Further work on the economics of this system need to be undertaken and will be done as this study continues. While there is more work to be done the initial yield and LER results show this system has the potential to increase productivity in medium to high rainfall zones of Southern Australia.

Acknowledgements

We acknowledge the support of the Future Farm Industries CRC for a PhD scholarship for Penny Roberts Craig.

References

Dear BS, Moore GA and Hughes SJ (2003) Adaptation and potential contribution of temperate perennial legumes to the southern Australian wheatbelt: a review. Australian Journal of Experimental Agriculture, 43, 1-8.

Egan P and Ransom KP (1996) Intercropping wheat, oats and barley into lucerne in Victoria. Proceedings of the 8th Australian Agronomy Conference 1996. www.regional.org.au/au/asa/1996/. Accessed July 2005

Harris RH, Hirth JR, Crawford MC, Bellotti WD, Peoples MB and Norng S (2007) Companion crop performance in the absence and presence of agronomic manipulation. Australian Journal of Agricultural Research, 58, 690-701.

Humphries AW, Latta RA, Auricht GC and Bellotti WD (2004) Over-cropping Lucerne with wheat: effect of lucerne on total plant production and water use of the mixture, and wheat yield and quality. Australian Journal of Agricultural Research, 55, 839-848.

Mead R and Willey RW (1980) The concept of a ‘land equivalent ratio’ and advantages in yield from intercropping. Experimental Agriculture, 16, 217-228.

Robertson M, Gaydon D, Latta R, Peoples M and Swan A (2004) Simulating Lucerne/crop companion farming systems in Australia. Proceedings of the 4th International Crop Science Congress, Brisbane. www.cropscience.org.au/icsc2004/symposia/6/1/926_robertson. Accessed July 2005.

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