Figure T2.3-1 The effect of plant population and row spacing on the dry matter production of sowthistle (Widderick 2002)
In a similar study in Mullewa, Western Australia, Riethmuller and McLeod (2001) showed that there was no impact on the yield of chickpea (cv Sona) by increasing the row spacing from 19 cm to 76 cm. Similarly, work at Wagga Wagga, New South Wales (Lemerle et al 2002), showed a relatively small impact of wider rows on the yield of field pea (cv Excell) despite higher annual ryegrass numbers in July at the narrow row spacing (Table T2.3-2).
Table T2.3-2 Effect of two row spacings on annual ryegrass density and field pea (cv Excell) yield at Wagga Wagga, New South Wales (Lemerle et al 2002)
Row spacing Annual ryegrass Field pea yield (cm) in July (plants/m2) (t/ha)
23 98 2.5
46 57 2.3
In Western Australia Jarvis (1992) found an average lupin yield increase of 3.6% in wide rows (36 cm) compared to standard rows (18 cm) across a range of environments.
w eed co nt ro l.
Careful selection of the most appropriate tactic allows cropping rotations to continue, even where resistance to some herbicide modes of action has already evolved.
Additional benefits from use of wide rows include the following:
Wide-row cropping enables increased quantities of crop residues to be retained, thus reducing the potential for erosion and improving soil characteristics.
Wide-row cropping enables easier sowing into retained crop residues.
There is an option to use smaller tractors with less tynes per sowing width, thus reducing costs.
Wide rows can reduce crop foliar fungal disease incidence by allowing better airflow within the crop canopy.
Wide rows work well with tramlining and controlled traffic farming, adding benefits associated with reduced soil compaction and more accurate and timely application of inputs.
Wide-row cropping provides opportunities for precision fertiliser placement such as side dressing.
Shields allow spraying between crop rows. Some drift may occur if too many fine droplets are produced. Shielded sprayers such as this have a higher drift risk due to the open shield.
Photo: Warwick Felton
Inter-row cultivation using the Robocrop inter-row cultivator. Wide-row cropping, especially with GPS guidance, allows cultivation with little damage to the crop.
Photo: Malcolm Taylor
Key practicality #1
Reduced competition from the crop can result in lower yield potential if weeds are not controlled.
Crop competitive ability will reduce as row spacing increases and crop density falls. Minkey et al (2000) reported that in wheat, in the absence of selective herbicide, the total number of annual ryegrass seed heads was reduced as row spaces were narrowed and crop density increased. Therefore, at increased row spacing the need for weed control by herbicide or mechanical means is also increased.
Due to slow canopy closure of the crop, the timing and effectiveness of weed management becomes critical to prevent yield loss and reduce the impact of weeds.
Key practicality #2
A chan ge to w ide rows w ill requ ire modificat ions t o s ow in g equ ipm en t , a com plet e ch an ge in equipment or use of a contractor.
Although excellent specialised row-planting equipment is available, wide rows may be sown using modified air-seeders and combines.
Key practicality #3
Precision farming technologies fit well with wide r ow s fo r w eed m an agem ent.
Technologies such as global positioning system (GPS) guidance and controlled traffic farming easily fit with wide-row cropping and weed management.
Warwick Felton, Di Holding and Andrew Storrie
Felton, W., Haigh, B. and Harden, S. (2004). Comparing weed competition in chickpea, fababean, canola and wheat. In Proceedings of the 14th Australian Weeds Conference, Wagga Wagga. pp. 304–307.
Fettell, N. (1998). Pulse crops for central western NSW. In Central West Farming Systems Research Compendium, pp. 16–18.
Gill, G.S. and Holmes, J.E. (1997). Efficacy of cultural control methods for combating herbicide resistant Lolium rigidum. Pesticide Science 51: 3 52–358.
Jarvis, R.J. (1992). Lupin row spacing. Western Australian Department of Agriculture Tech note No. 2/92.
Lemerle, D., Sutherland, S., Koetz, E. and Smith, A. (2002). Suppressing weeds in conservation farming. In Proceedings of the 13th Australian Weeds Conference, Perth, pp. 705–708.
Minkey, D., Hashem, A., Riethmuller, G. and Harries, M. (2000). Effect of seeding density, row spacing and trifluralin on the competitive ability of annual ryegrass
in a minimum tillage system. In Western Australia Crop Updates 2000.
Riethmuller, G. and McLeod, W. (2001). Effect of row spacing and orientation on growth and seed yield. In Crop Updates (Pulse research and industry development), Western Australia, pp. 38–40.
Widderick, M.J. (2002). Ecology and management of the weed common sowthistle (Sonchus oleraceus L.). PhD thesis, University of New England, New South Wales.
problems for the development and management of
herbicide resistant weeds. Work with resistant weed populations (Storrie, unpublished) has shown that inter-row spraying with low-risk herbicides is essential for the management of resistant or hard-to-kill weeds.