Riverine Plains Inc has secured a GRDC investment to run the Southern NSW Trials – Optimising crop nutrition in canola project.
The project was designed in response to farmers in southern NSW over the past few seasons who have been questioning the accepted requirements of in-season sulphur (S) in canola.
Traditionally, up to 20-24kg S/ha is applied prior to, or onto a canola crop. However, given canola-wheat is now a key cropping rotation and many paddocks have good history of S application, and there is also evidence of S accumulation at depth, growers have been questioning if that amount is actually required for each canola crop.
As part of the project, two field trials are being conducted to generate local information and to provide an economic analyses of the response.
Field Trial – 1, Howlong, NSW
A replicated trial will be run at Howlong to determine the response curve for S in canola under a classic cereal-canola rotation. This will involve five replicates of different rates of in-crop S (0, 10, 20, 30, 40 kg S/ha), applied as Sulphate of Ammonia (SOA). The trial is taking place in an irrigated paddock, with high rates of N applied to ensure N supply does not limit plant uptake of S.
Field Trial 2 – Yarrawonga, Victoria
Background nutrition (especially N) may cause a variable response to S. If N supply is not optimal, plant S uptake may be less than required. As such, a second trial, featuring a detailed study of N x S interactions in canola, has been sown at the Riverine Research Centre (RRC), Yarrawonga. This trial has four replicates of canola, over which combinations of S and N rates will be applied as follows;
- N applied as urea in a split application (50:50) between 6-8 leaf stage and early bolting at five rates (0, 40, 80, 120, 160 kg N/ha).
- S applied as SOA at four rates (0, 10, 20, 30 kg S/ha). The S treatments will be applied across the suite of N treatments to determine the interaction between N and S.
This trial will tease out the interactions between N supply and S uptake, to ensure that S uptake is not limited by suboptimal rates of N.
If the economic analyses show equivalent economic returns under lower S rates, this may provide the basis for further investigation around regionally-specific S requirements in canola in southern NSW, after background S levels are known.
Results from 2018
Interim (2017) results from the project were published in the 2018 edition of Research for the Riverine Plains and are available for download via the following link:
2018 Optimising sulphur and nitrogen nutrition in canola