| Researcher(s) |
Linda Bailey |
|---|---|
| Year(s) | 2022 |
| Contributor | Northern Grower Alliance |
| Trial location(s) |
Springvale, QLD
|
To evaluate the impact of sorghum row spacing and plant population on fallow efficiency
This trial was designed to investigate the impact of sorghum row spacing and plant population on fallow efficiency. The ‘establishment’ crop of MR Buster sorghum was sown in November 2021, using a double disc MaxEmerge XP planter. The grower’s standard practice was ~60,000 seeds/ha on 100 cm rows.
Comparison treatments on 50 cm row spacings were established by planting plots in two passes: offsetting the planter on the second pass. Treatment 2 aimed at the same plant population as the grower’s standard but on 50 cm rows, treatment 3 used the grower standard sowing rate to evaluate the impact of 50 cm row spacings and double the grower’s standard plant population.
Early site access was limited by heavy rainfall with establishment only assessed 43 days after planting (43 DAP1). The grower’s standard treatment established ~6 plants/m2 on 100 cm rows (treatment 1). This allowed a sound comparison of the impact of increasing plant population and reduced row spacing (treatment 3). However, treatment 2 had a significantly higher plant population than targeted (9 plants/m2 rather than 6) on 50 cm row spacings. This meant there was not a sound comparison of the impact of increased row spacings alone (treatment 2 v 1) or the impact of increasing plant population alone (treatment 3 v 2).
The trial received extremely high in-crop rainfall of ~700 mm (~180% of long term mean rainfall) with harvest in late April. There was a trend (p=0.10) for both 50 cm row spacing configurations to increase yield by ~7-8% (~0.3-0.35 t/ha) compared to the standard practice (4.36 t/ha). It would appear that row spacing may have had more impact on yield in the ‘establishment’ crop rather than plant population alone as there was no significant difference in yield between treatments 2 and 3.
Four days later, an EM38 survey and a groundcover assessment were conducted. The EM38 survey showed no differences in conductivity at either the shallow depth (0.375m) or the full assessed depth (1.5 m), indicating soil moisture levels at the start of the fallow were equivalent between the treatments. The rating of groundcover indicated that both 50 cm row spacing treatments had produced significantly increased ground cover (~68%) than the 100 cm spacing (55%).
The ‘evaluation’ crop was sown in October 2022, following >300 mm of winter fallow rainfall (~200% of long term mean). An EM38 survey was unable to be conducted at the end of fallow but was conducted early in-crop. The EM38 results showed no significant differences between treatments for soil moisture.
Sorghum emergence was assessed at 34DAP2 with equivalent plant populations in all treatments.
There were no significant differences in yield between treatments (~6.1-6.3 t/ha).
The ‘establishment’ phase of this trial was conducted under very wet in-crop and fallow conditions. In this situation, differences in fallow efficiency could not be demonstrated. However, there was a clear trend to increased yield in the establishment crop phase from the combination of narrow row spacings and increased plant population. In the absence of any difference in fallow efficiency or soil water availability for the ‘evaluation’ crop, there was no impact on establishment or crop yield.
In this situation, no data was generated to indicate that narrowing row spacing or increasing plant population in the establishment crop may lead to significant benefits in fallow efficiency or the yield of the following crop.
| Lead research organisation |
Northern Grower Alliance |
|---|---|
| Host research organisation | N/A |
| Trial funding source | GRDC NGA2009-002RTX |
| Related program | N/A |
| Acknowledgments | N/A |
| Other trial partners | Not specified |
| Crop type | Cereal (Grain): Sorghum |
|---|---|
| Treatment type(s) |
|
| Trial type | Experimental |
| Trial design | Replicated |
| Sow date | Not specified |
|---|---|
| Harvest date | Not specified |
| Plot size | Not specified |
| Plot replication | Not specified |
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.
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