How To: Make the most of your spreading

One mistake most farmers make from season to season, according to registered calibration specialist Russell Nichol, is neglecting the maintenance and set-up of their spreaders before each use.

Speaking at a recent fertiliser calibration field day at Pleasant Hills in the Riverina region of New South Wales, Nichol says producers need to check each and every component of their machines prior to each season to ensure that they are fit for use.

"Bent spinners, worn out blades, general maintenance on spreaders is critical, they need to treat their spreaders as a piece of precision machinery," he says.

"It’s not just a piece of equipment to pull out of the shed once a year – that’s the biggest problem – they are not looked after from one year to the next."

Nichol, of the Australian Fertiliser Services Association, carries out Accu-Spread certification for professional contract spreaders and farmers across Australia.

At the field days, hosted by producer network Riverine Plains on June 6, four spreaders were put to the test – the Amazone ZA-M 3000 Ultra, Amazone Profis 3600L, Amazone ZA-M 1501 3-point linkage and Landaco TS10000 trailing spreader.

Riverine Plains research and extension officer, Dr Cassandra Schefe, says the field day was aimed at ensuring fertiliser spreaders were set up correctly to improve the uptake efficiency of nitrogen applied in-crop.

Proper calibration saves money

According to a research done by the South West Catchments Council and Department of Agriculture and Food Western Australia in 2013-2015, the majority of fertiliser spreaders were delivering a high level of variation in spread pattern, and that a new machine was no guarantee of an even application.

The economic implications of urea spread patterns for 19 spreading machines were evaluated for the research, and showed that uneven spreading on pastures resulted in a $15-$40/ha reduction in the value of dry matter for a single application.

According to Nichol, an even application across the paddock needs to be achieved to optimise the benefits of fertiliser, which can be done by overlapping the spread pattern of the previous run.

"That is, not more than 15 per cent between your highest and lowest point in the paddock, creating an even application," he says.

"A lot of the linkage spreaders will get there if they are set up correctly – if not, they will be throwing what I call devil’s horns, which is too much fertiliser out wide and not enough behind the machine.

"It is a matter of making adjustments to get that right."

The calibration tray test

The four spreaders did two test runs each to test bout width, or the distance between spreader runs to provide the overlap.

Plastic trays were lined up one metre apart on a 60m line to determine the spread pattern.

The spreader was turned on 30m before reaching the trays, and turned off 30m after straddling the centre tray.

Graphs were generated on the Accu-Spread model using the material collected in the trays during each test run, with new settings or adjustments made and the machines re-tested for an improved spread pattern.

The spreaders were set on 30m at 100kg/ha and driven at a maximum of 30km/h to reduce wind turbulence.

"The outside trays are collecting only 0.1 to 0.2 grams, so we do two test runs to collect enough granules to weigh," Nichol says.

"About 60 to 70 per cent of the urea in the marketplace today is around two to 3.75mm in particle size, and 30 per cent is 3.75 to 4mm.

"Those smaller granules have no velocity and won’t throw out – farmers need to pressure fertiliser suppliers to ensure they are doing the testing and supplying good product.

"When we are spreading 36 to 42m, we’ve got to have good, consistent product."

Nichol says limiting the times urea was put through an auger helped maintain a larger granule size.

Different fertiliser products have different physical characteristics so it is normal for the same machine to have different bout widths for each product.

Driving accurate and consistent bout widths is critical to achieving an even spread.

Results

One of the machines under test spread urea at 100kg/ha across 36m at a spinner speed of 720rpm, and running OM 2448 spinners on a vane setting position of 55-14.

The test revealed a bout width of 13m.

"That tells us, if the operator drives at 13m he will have 15 per cent coefficient of variation, but if he drives at 30m, it will have 25 per cent coefficient of variation, and that goes out to 35 per cent at 36m," Nichol explains.

"Typically what creates that pattern, is the short vane throwing out to where the big vane is throwing. I would drop the big vane back as that’s what is throwing it out too wide, and I would increase the short vane to 21."

"Good advice is to get the operator’s manual out and read it before you start your new spreader."

Nichol advises farmers to use spreading contractors certified under Accu-Spread and with Fertcare trained drivers.