Training puts precision agriculture to work - Part 2

Part 1: Training puts precision agriculture to work


Owners: Chris, Leanne, Colin and Althea Hunt
Location: 30km west of Mildura, Victorian Mallee
Farm size: 4700 hectares
Annual average rainfall: 275 millimetres
Soil types: heavy clay flats rising to deep sand
Enterprises: wheat, feed barley, canola, export
oaten hay and field peas

Like many growers in recent years the Hunts acquired the equipment needed for precision agriculture (PA) but lacked the knowledge to fully utilise it.

They needed specialised training, which is now being provided through the GRDC-funded PA groups. For the Hunts, the outcome of this training is a far tighter control over inputs used on their 4700 hectares of typical Mallee dune/swale country near Mildura, Victoria.

Over the past two years, the Hunts – Chris and his father Colin – have moved to a fully automated variable rate (VR) program at seeding. Chris says that attending a SPAA Precision Agriculture Australia training day helped them to start making use of the technology and identify what else was required.

They both knew from experience and local trial work that a blanket rate on their country was not an option. Indeed they had been varying rates manually for 15 years. 

Their move into PA began in 2007 with the use of an AutoFarm A5 steering unit using a real time kinematic (RTK) satellite navigation system for guidance.

The system is moved between the John Deere 9200 tractor used for seeding and the Case 2588 harvester.  

To achieve a full and more automated VR fertiliser and seed program, Chris has since made three main changes.

Image of a man sitting in tractor cab

Chris Hunt integrated precision agriculture
technology from a range of manufactures but has
avoided equipment compatibility issues by running
independent displays for each unit.

Yield data was collected using the AFS Pro600 display and software already installed in the harvester. After attending the training, Chris was able to convert this data into actual fertiliser maps.

A year later the Hunts added a Topcon X20 rate controller to the Bourgault airseeder, as well as an extra bin to provide separate bins for monoammonium phosphate (MAP) and urea at seeding.

Sulfate of ammonia and urea are also top-dressed on specific areas using an Amazone spreader. This is done by manually changing rates as the tractor enters a different zone, as shown on the AFS Pro600 display.

Chris processes his own data to make zone maps but is considering using a service provider to help “tidy-up” the zones. 

VR seed and fertiliser

For seeding in 2013, yield data, biomass and elevation data will be used with Google Earth images and ‘gut feel’ to create the fertiliser and seed zones.

Chris aims to have three to four phosphorus zones, two to three nitrogen zones and one or two for sulfur.

Next year will be the first time that Chris will use variable seeding rates. His aim is to run with two rates, the higher on the dune, where crops tend to be thinner and less tillered.

The main zones are defined as high, mid, low and heavy, based on yield potential. The actual rate of MAP or urea at seeding is determined by the crop, paddock and subsoil moisture.

Image of new crop growing in a field

The productivity of the sandy dunes versus the
moisture-limited heavier clays of the swales clearly
showed up in 2012 when in-crop rainfall was about
80 millimetres. Where hay had been sown, rather
than canola, these swales had more stored water
and higher yield potential.

PHOTO: Emma Leonard

  • High zone – covers the peaks of the sand hills, which have high yield potential but also high input requirements. The soils are sand to sandy loam. At seeding, this zone is high for phosphorus (25 to 40 kilograms/ha MAP) and nitrogen (20 to 40kg/ha urea) and is where the majority of sulfur and nitrogen is top-dressed during the growing season. Seeding rates in the high zone, the mid zone and the low zone will be 30kg/ha wheat, 35kg/ha oats, 32kg/ha barley and 1.1kg/ha canola.
  • High zone with poor crop response – covers  the tops of some of the sand hills where erosion has occurred. This zone will be sown to wheat, barley or oats at 50kg/ha.
  • Mid zone – covers areas on the sides of the sand hills, which have sandy loam soil and good yield potential. This zone is less deficient in nutrients than the high zone. At seeding MAP and urea are sown at 25 to 30kg/ha MAP and 0 to 20kg/ha urea. This area is top-dressed with urea and sulfate of ammonia when sown to canola. Otherwise, top-dressing is determined by season, crop, history and budget.
  • Low zone – covers the flats or swales between the sand hills that are a heavy loam soil type. Annually, yield potential varies greatly with lack of moisture and soil constraints such as boron limiting yield. This zone has high nitrogen and phosphorus levels and so only receives 0 to 25kg/ha MAP and no urea at seeding. Even in wet years no additional fertiliser is top-dressed in this zone.
  • Heavy zone – covers about 10 per cent of the 1500ha that is share-farmed. These areas are not seeded as they rarely produce and no fertiliser is applied.

While the Hunts have not produced their own figures to measure the benefit this VR approach is providing, they use figures produced by their consultants. Figures for the 2011 season showed that for every $1 spent on sulfur on the sandy soils the return was $5 and for nitrogen the return was $3, while for phosphorus the return was only about $1.20. Consequently, zoning for phosphorus is more about saving inputs, while zoning for nitrogen and sulfur relates to building yield.

The Hunts are using PA technology from a range of suppliers. They have not had problems with equipment compatibility but believe this is partly due to the fact that a separate display is used for each item. For example, the Topcon X20 only controls the Bourgault airseeder box, while autosteer is controlled through the AutoFarm system at seeding.

While Chris acknowledges there can be equipment compatibility issues, he does not believe farmers should let that concern stop them adopting PA.

“It can be hard to find the information you need, but talking to those who are already using PA and courses such as those run by SPAA are a great help.”

More information:

Chris Hunt
0428 284 245

PA in Practice II
To order your guide, visit the GRDC Bookshop or see page 2 of the Ground Cover Direct November 2012 - April 2013 catalogue.

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