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.
Improved yield
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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Disc seeding systems
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.
A desire to reduce costs of seeds
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).
Assess the value of precision planting
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.
Uniformity in plant spacing
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.
