Growers have moved in and out of raised beds as
the seasons have varied.
PHOTO: Brad Collis
According to water use efficiency modelling, growers in southern Victoria and Tasmania’s high-rainfall cropping zone should be harvesting 12-tonne-per-hectare wheat crops this coming harvest. For several reasons that’s highly unlikely, and it is the question of how to achieve this potential that remains the primary challenge for the 450 member-strong Southern Farming Systems (SFS).
SFS CEO Jon Midwood, who leads 10 full-time staff in the 18-year-old organisation, suggests one solution to achieving consistently high yields from 500 to 1000 millimetres of rainfall in a varying climate could be “making the bucket bigger”.
“If you doubled your effective soil depth, which would give you another 30 to 40 centimetres of soil, you could potentially double the capacity or size of your cropping area, or its production capability,” he says.
This bigger bucket would work by buffering the moisture available to the crop, rather than swinging from dry to overflowing or waterlogged, particularly in the more sodic subsoils in the winter.
SFS research has shown that water-holding capacity can be improved through deep banding chicken manure or compost, which, in some trials, doubled yield. The next step is to overcome the challenges of scale and supply of these or similarly suitable soil amendments.
The worst rainfall scenario for high-rainfall zone (HRZ) growers, Mr Midwood says, is a wet summer followed by a typical autumn/winter with high rainfall, followed by a dry spring with the tap effectively turned off in the crucial September and October grain-filling period. This leaves shallow-rooted plants unable to access any residual moisture at depth.
Despite starting this season with an “empty bucket” and a late start to sowing, Mr Midwood says HRZ cereal and oilseed crops were “sitting pretty” by mid-winter, with growers working to avoid a repeat of last year’s soft finish, which resulted in high-yielding but low-protein crops.
However, HRZ growers are, almost by default, tireless innovators: “When there is an opportunity, they go for it … stick their neck out in the risk versus reward analysis,” Mr Midwood says.
“Earlier sowing, timeliness of spraying, fertiliser decisions and optimising nitrogen use are all tools for making money when it is there to be made.
“We find that it is the growers who capitalise on the good years who are the most adaptable.”
That same adaptability to a changing environment is being played out in the swing in and out of crop growing systems, such as raised beds. Raised beds fell out of favour with many growers during the dry years at the start of the millennium, but the return of wet years since 2010 has seen a resurgence in the creation of two and three-metre beds and the renovation of old raised beds.
“It simply highlights the need to be adaptable in a changing climate,” Mr Midwood says.
“It’s the same with livestock. In the early years of SFS we had a lot of growers move to 100 per cent cropping, but then as lamb prices took off again there was a swing back to mixed farming as growers looked to spread risk.”
The wet years have also seen a swing back to burning stubbles. “High stubble loads block machines at sowing and increase the relentless problem of slugs in newly emerged canola and cereal crops.”
On the SFS’s short-term research agenda are:
herbicide resistance – random testing of ryegrass growing in HRZ paddocks shows far higher resistance to group A and B herbicides than expected;
slug and pest control – many growers now consider slug control part of the program but would like to avoid this costly exercise;
subsoil constraints – improved subsoil conditions would dramatically enhance crop and pasture productivity, enhance the soil resource and enable increased levels of soil carbon to be stored; and
breeding and/or identifying longer-season grain and oilseed varieties and suitable agronomy packages for those varieties that can be sown early yet avoid the frost risk and need less moisture for grain fill.
03 5265 1666,
Gold for industry stalwart
Three-metre beds lift HRZ production
GRDC Project Code
SFS00019, SFS00023, ULA00008