THE quantities of farm inputs may not have been reduced, but they are now being targeted much more effectively since variable rate application technology (VRT) has been introduced on a large-scale farming aggregation in the NSW Riverina.

GPS screen showing the different colours representing different lime rates.

The adoption of VRT for lime and fertiliser inputs on Warakirri Cropping’s 10,000-hectare Cowabbie-Mukoora aggregation that covers a string of separate holdings spread over 100 kilometres between Ardlethan and Narrandera has added a new level of farming precision to the extensive dryland cropping business.

In particular, it has allowed more prescriptive management of the many different soil types that occur throughout the aggregation.

Manager, Trent Gordon, said with the help of technology supplier, Precision Agriculture, they mapped the farms into different zonal areas depending on the different soil types.

“Instead of farming paddocks as whole blocks we now divide it into soil types within the blocks. We are trying to put a bigger emphasis on our soils. We think that is where we can start picking up the biggest benefit by improving the soils so we can grow better yields,” he said.

With the farms already operating with autosteer guidance on a three-metre controlled traffic farming system using 12-metre equipment, Mr Gordon said they had progressively introduced VRT over the past three years, starting with lime and gypsum applications.

Variable rate lime spreading.

“We got Precision Ag to do pH mapping and EM surveys. From those we have drawn a variable rate lime map and a variable rate gypsum map,” he said.

“With the lime and gypsum, we are not saving big amounts but we are putting the right amounts where they need to go. That will really help us. We have to improve the spots that need improving.”

Mr Gordon said two years ago they started doing variable rate application of nitrogen on the cereals, and last year adopted variable rate nitrogen across the whole farming program.

“With the variable rate nitrogen we are learning that we can push the better areas a lot harder when we have the moisture. We can track back on the non-productive areas if they have more nitrogen from the soil tests,” he said.

“Last year we put a lot more nitrogen on than usual, but that was because of how wet the year was. The year before we put the same amount on we would have done in the past, but we were able to target the areas that needed it more.”

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Mr Gordon said last year the business moved into the variable rate application of MAP fertiliser on barley and this coming season would try to do the whole farming program with variable rate MAP.

Seeding equipment used on Warakirri’s Cowabbie-Mukoora aggregation in southern NSW.

As with the other inputs, the MAP is applied at different rates through the various zones based on the different soil types.

“To come up with those zones we have used yield data from the headers over the years, EM surveys and DVI satellite imagery. We combine all those to draw our zone maps,” Mr Gordon said.

The variable rate MAP is applied at sowing time with two Seed Hawk planters fitted with John Deere boxes while all the other spreading is done with a Bredal spreader that holds 15 tonnes of lime and 10t of urea.

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Warakirri is a corporate farming company. The sole investor is REST Superannuation Fund.

Warakirri Cropping owns and operates approximately 80,000ha of broadacre cropping farms in Victoria, southern and northern NSW, southern Queensland and Western Australia.