Take Home Messages
- 6-inch row spacings had a significantly higher yield than zero and 12-inch row spacings.
- Sowing density had no effect on yield or protein.
Aim
To investigate the effects of row spacing and sowing density on wheat yield.
Background
In no-till farming systems, row spacing is known to influence crop performance. Narrower row spacings to 15cm lead to higher plant height, plant biomass and grain yield in wheat (Shafaqat et al., 2016). However, there is little research on the feasibility of zero row spacing systems in broadacre wheat crops. Sowing density can also be an important management factor to ensure individual plants can maximise access to resources by reducing weed competition and causing lower evaporation on more heavily canopy-shaded ground. This Victorian Drought Hub initiative aims to investigate if row spacings and sowing densities can affect wheat yields through possible mechanisms of superior water use efficiency and crop competition. This will be useful information for farmers looking for mitigation techniques in drought years.
Paddock Details
Location: Nullawil
Crop year rainfall (Nov–Oct): 497mm
GSR (Apr–Oct): 384mm
Soil type: Sandy Clay
Paddock history: Lentils
Trial Details
Crop type: Scepter Wheat
Treatments: Refer to Table 1
Target plant density: Refer to Table 1
Seeding equipment: Knife points, press wheels
Sowing date: 22 May 2022
Replicates: Three
Harvest date: 15 December 2022
Trial average yield: 4t/ha
Trial Inputs
Crop nutrition, weeds, disease and pests managed as per best practices
Method
A split-plot trial was set up in Nullawil, with treatments outlined in Table 1. Zero row spacing was achieved by hand spreading 30 per cent of the plot’s seed over bare ground, followed by sowing 70 per cent of the plot’s seed at 12-inch row spacings.
Results & Interpretation
Plots with 6-inch row spacings had significantly higher yields than those with zero and 12-inch row spacings but there was no significant difference in grain protein (Table 2). There was no significant interaction between row spacings and sowing rate. The 6-inch row spacing most likely had superior nutrient and water access due to reduced competition from single wheat plants and crop weeds. Sowing density had no significant effect on grain yield or protein (Table 3).
Commercial Practice and On Farm Profitability
We expect crops with zero row spacing to have superior yield in low moisture conditions, due to higher crop competition and nutrient utilisation by giving each plant its own space, rather than causing them to compete for intra-furrow resources. Years with rain closer to a decile 5 or lower may enhance a treatment effect. Whilst there is a good theory behind it, there are some particle limitations to zero row spacing systems. Firstly, pre-emergent herbicides cannot be used as seed is broadcast into the inter-row where the herbicide sits. The only option for weed control at sowing was pyroxasulfone applied as PSPE, which reduced the spectrum of controllable weeds.
The most sensible way for the trial to achieve zero row spacings required us to hand spread seed at sowing. This is obviously not possible at farm scale, but growers in the Mallee have used splash plates to spread seed while sowing to achieve zero row spacing. If further work into zero row spacing is done, 6-inch row spacings should be sown over hand spread plots, to cover more ground and enhance crop competition.
References
Ali, S., Zamir, M.S.I.I., Farid, M., Farooq, M.A., Rizwan, M., Ahmad, R. and Hannan, F., 2016. Growth and yield response of wheat (Triticum aestivum L.) to tillage and row spacing in maize-wheat cropping system in semi-arid region. Eurasian Journal of Soil Science, 5(1), pp. 53–61.
Acknowledgements
This trial was funded by the Victoria Drought Resilience Adoption and Innovation Hub with support from the Australian Government’s Future Drought Fund.
