Trials with growers in Australia show that precision planting improved the uniformity of crop stands and often allowed reductions in plant density without loss of yield. This can lead to potential benefits that will be greatest in crops with high seed input costs.
This is one of the conclusions of the recent paper ‘The agronomic value of precision planting technologies with winter grain crops’ of the Grains Research & Development Corporation (GRDC). The paper focuses on the results of field trials and the experiences of growers using precision planters.
Grain yield responses to precision planting have been variable in the project trials to date. This suggests adoption of the technology may not be warranted based on crop yield response alone.
The emergence rate of the trials varied considerably. In canola trials there were both significant increases and reductions in seedling establishment with precision planting. However there was a consistent improvement in the uniformity of the interplant spacing with a 20-40% reduction in the coefficient of variation (CV ) for interplant distance.
Crop establishment in pulses was generally higher than in canola. As with canola, there was no consistent effect of precision planting on establishment and crop uniformity was improved substantially.
Precision planting improved grain yield by 18% or 22% in faba bean. Significant increases of 10% (lupin) and 14% (lentil) were also measured. The results for canola and pulses indicated that despite variable effects on establishment, precision planting resulted in yields equivalent to or higher than those achieved with conventional sowing.
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Currently most commercial precision planters in Australia use disc seeding systems with a vacuum or positive pressure seed singulation system located on each seed row which allows accurate placement of individual seeds within the row. This technology is well known to summer crop growers in the northern region, but it is in its infancy in the southern and western regions of Australia.
The recent interest in using precision planting technology with winter crops, especially in hybrid canola, has been prompted in part by a desire to reduce the costs of using hybrid seeds and has been spurred on by reports that even placement of seeds improves yields at low plant densities, which would allow significant reductions in seeding rates.
Recent work in Western Australia in canola and lupin indicates that even spacing, to minimise interplant competition, may allow a reduction of sowing rates below current recommended rates, with predicted savings of AU $ 24 per ha in seed of hybrid canola (Harries et al. 2019).
While these results are encouraging, there has been no systematic assessment of the value of precision planting technology in winter crop production for small grain crops in Australia. The aim of the current project of the GRDC is to assess the value of precision planting in canola and numerous pulse crops in the southern and western regions.
The relationships between grain yield and established plant number were examined because of the variable effects of precision planting on both plant number and yield. Among all the trials, three types of responses were evident. There was no difference in the response to plant density between the conventional and precision planting. Researchers found a consistent yield advantage of precision planting over a range of plant densities. And there was a greater ability to maintain yields at low density by precision planting.
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A consequence of the latter two responses is that precision planting would allow a reduction in plant density with little or no yield penalty. Similar relationships were reported by Harries et al. (2019) in comparisons between unevenly spaced and evenly spaced plantings, suggesting the responses in the current trials were associated with differences in the uniformity in plant spacing within the crop.
The potential economic benefit of this is the saving on seed costs from producing the same yield with fewer plants per m2 and little yield penalty. However, the responses to precision planting varied among experiments and it is still unclear what the main factors that influence the response are.
Growers survey: ‘Improved yields often not the primary aim’
Improved yields were often not the primary aim of adopting precision planting, a survey among Australian growers that participated in trials shows. Major considerations were improving crop establishment and increasing the uniformity and vigour of the crop stand, as well as improved crop-weed competition. Growers were also looking to reduce seed costs without a loss in yield.
A small number of growers are pioneering the use of precision planters in winter cropping across the southern and western regions of Australia. The participants in the trials used a wide range of equipment, ranging from old summer crop planters to newer, high-technology precision planters.
About half the growers grew irrigated crops with a significant component of maize cropping, while in dryland systems numerous growers have also grown opportunity summer crops, often as part of their adoption of precision planters. The standard planting equipment comprised twin disc row units, with only one planter using tyne-based row-units.
Precision planters were used mainly to sow canola and a range of pulse crops (faba bean, lentil and chickpea), with some limited attempts at planting cereals. Growers said they initially adopted the technology because they anticipated improved accuracy of seed placement with discs, resulting in better and more even crop emergence and an even distribution of seeds in-furrow to minimise interplant competition. Growers also were aware of reports from overseas of reduced seed costs per hectare.
The growers in the survey confirmed these benefits and reported reduced seed costs per hectare, especially with hybrid canola, as well as more uniform crop emergence and vigour and improvements in accuracy of seed placement. Improved yields were not always reported, but when cited, occurred mainly in canola and faba bean.
The main problem and limitation that the growers encountered with the use of precision planters was the lack of local technical support and advice, unlike growers and dealers in the northern regions, where precision planter technologies are well-known. Growers who had acquired lower cost, older generation planters encountered the most difficulties with adapting their equipment (designed for summer crops) to winter cropping.
The practical difficulties growers faced with trying to adapt new technology to their farming systems led to some limited dis-adoption of precision planters, but not a rejection of the technology. One early adopting and innovative grower commented they were now ‘waiting for better technology to handle sticky clay conditions …. despite some definite success’.
Growers provided the following key recommendations for adopting and operating precision planters:
• The benefits of seed singulation are not realised unless accurate seed placement can be delivered, through technology features, settings and operation, and including low paddock roughness.
• Plan the shift to precision planting, and address soil constraints, paddock preparation, seed grading, cleaning, quality, residue, weed management and logistics.
• Do some homework: research, talk to users and manufacturers, and look internationally for up‐to‐date information.
• Ensure technical support is available with the choice of technology or be ready to struggle.
• Be confident in your choice of planter or delay selection until you are.
• Hi‐Tech planters may not imply higher cost‐effectiveness.
• Use clean seeds, graded and of high quality.
• Keep an eye on performance, monitor regularly, be conscious of speed.
• Precision planting of larger seeds is less challenging when starting.