Precision agriculture in vegetable production

Narrator: Variable-rate (VR) technologies are based on the principle that not all fields are uniform, and therefore, crops should not be managed uniformly. These technologies allow inputs—such as fertiliser, lime, irrigation, and pesticides—to be applied at different rates within a field. They are increasingly being used in vegetable production.

VR applications are commonly based on soil mapping, along with soil analysis or ground-truthing, to confirm which inputs are needed and create accurate prescription maps.

David and Will Whishaw use VR technologies to improve their production of peas, beans, shallots, and onions near Carrick, Tasmania.

Will Whishaw (Armidale Stud Tasmania): We’re currently using 2 sorts of VR technology. One is VR irrigation, and we’ve also recently invested in a machine that maps soil pH. With this, we are now able to apply lime at variable rates.

We’re trying to increase productivity in the area that we have.

As for VR fertiliser—or lime, in our case—it’s all about evening out the soil pH. We’ve found that our pH ranges from as low as the low 5s to as high as 7.0 to 7.3. We’re targeting a pH level somewhere between 6.5 and 7. Using VR spreading and soil mapping, we’re working towards this goal.

Narrator: The Whishaw family uses Veris soil pH mapping to measure pH variability across their fields. These fields are then split into management zones, where lime application rates are assigned to each zone and captured in a prescription map.

The VR system's controller adjusts application rates automatically based on the needs of each zone.

VR irrigation allows irrigation rates to vary depending on soil types and the water requirements of different crops. Soil mapping (such as EM38 mapping) forms the foundation for VR irrigation, as it identifies differences in soil characteristics like texture, structure, and water retention. Irrigation rates are then adjusted accordingly for each soil type.

Jaco Pauer manages irrigation at Parrilla Premium Potatoes, a farm located in South Australia's east that produces carrots, potatoes, and onions. Parrilla Premium Potatoes has progressively adopted VR irrigation across the dune-swale terrain on its farm.

Jaco Pauer (Parrilla Premium Potatoes): We started using VR irrigation about 8 years ago when we identified problem areas in our paddocks that were prone to waterlogging.

We conducted EM mapping and elevation mapping to get a basic communication map. We combined these to serve as a starting point for verification. We now use variable rates on the pivot.

Throughout the season, we also fly drones to check plant health and collect data. Our biggest aim is to improve the quality of our produce because premium produce earns better prices.

By applying water only where it’s really needed, we’re using water more efficiently. With a conventional pivot, the water is applied in a straight line, delivering the same amount over various soil types—whether they actually need it or not. Now, we can apply less water in low areas that hold moisture and more water in sandy areas that drain quickly. This approach has given us much more flexibility.

Narrator: When considering the adoption of VR technologies, key factors include:

• Is the variability large enough to make an economic impact?
• Is the variation caused by something that can be managed with VR technology, like nutrient deficiency or pH imbalance?
• Can the variability be clustered into manageable zones?

VR technologies target crop inputs toward areas where they are needed most.

This provides several benefits, including:

• reduction in total crop inputs
• more precise application of inputs for improved crop uniformity
• improved soil parameter uniformity.

VR technology is driving a more sustainable future, saving valuable resources and enabling higher yields of premium-quality produce.

End of transcript.