Precision agriculture: what you need to know and how to make the most of it

No doubt you would’ve heard the term precision agriculture being thrown around but how much do you really know about it? Precision agriculture is a booming sector and involves a variety of equipment and plenty of knowledge and resources to work so understandably, it can be a bit confusing for the average farmer.

But given the complexities around precision ag, growers need to do their homework and understand at what level they want to engage with before making the investment.

Precision agriculture specialist, Hamish McGrath, said the concept is commonly used for crop surveillance, surface water management, variable rate fertiliser application, soil management plans and digital farm mapping.

McGrath, of Precision Agriculture, Temora, NSW, said growers were investing at base entry points on simple yield maps right up to $50,000 for sophisticated data collection technology.

“There are all different levels of uptake by farmers – at the moment it is at the early adopter phase and growers are starting to see a real benefit from it,” McGrath said.

“But, it will eventually become one of those things everyone does.

“At a base level, anyone can drive around in a tractor looking at a map – it’s not the most accurate and you won’t get the most out of it, but a grower must see benefit at the lower end first and then move up as those smaller gains are achieved.

“At the top end, growers have seen up to a 25 per cent increase in yield – that is huge in a year like this with grain prices where they are.”

McGrath said a key starting point is collecting yield data and soil mapping to enhance the natural resource base and obtain more from every hectare.

Soil management plans cover soil sampling, zonal paddock management and variable rate gypsum application, elevation mapping and EM38 (measuring electrical conductivity of the soil).

But in terms of precision ag, it is more than just mapping the soil, McGrath said.

“There is always the question of how much money will it save people," he said.

“It’s more about getting the benefit out of the money you are already spending by reallocating resources to increase efficiency, pushing those better yielding areas more and bringing up the lower areas.

“In the past, a lot of people have pushed those good areas as hard as they could and left the low areas behind. Now it is bringing everything to a level playing field to increase input efficiency.”

Under precision agriculture, grid soil pH mapping has been shown as one of the most effective method for determining variable rate lime applications.

Grid sampling enables the grower to choose any combination of soil pH, Colwell phosphorus, Colwell potassium and exchangeable cation (Ca, Mg, K and Na).

The process involves eight soil samples collected at zero to 10cm depth every two hectares and these are analysed in an accredited laboratory.

Growers are able to match fertiliser rates to nutrient availability and determine areas to invest in soil repair programs.

“Some growers with high value crops are going to 0.25ha grids to generate maps for variable rate lime and gypsum, and phosphorous,” McGrath said.

Crop surveillance is accurately measuring crop growth at critical times for variable rate management strategies and mapping yield constraints.

Growers can implement targeted management applications for variable rate nitrogen, fungicide and crop growth regulants, hay production and weed mapping.

It can also be used to identify seasonal yield constraints such as waterlogging and pests.

Crop surveillance involves high-resolution satellite imagery of 10 to 15m pixel (captured every 15 days) to deliver agronomic tools such as NDVI (normalized difference vegetation index) analysis and vegetation field maps.

“Satellite imagery is a scouting tool used to determine crop emergence and performance,” McGrath said.

“For example, in this dry year growers have been able to see ryegrass seedlings germinating after a small shower of rain.”

McGrath said satellite imagery has come a long way and is now freely available to growers.

“Drones are ideal for looking at a small resolution size, but growers must ask if they need that small resolution and is it worth paying for that,” he said.

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“If you need that level of detail, then it’s worth it but there are platforms that can do field-by-field with a 10m resolution, and that is good enough for most farmers.

“For high value crops such as cotton or corn, a little more cost can be justified.”

But satellite data has its shortcomings, McGrath said.

“The issue with satellite data is it is being sold by the platform provider as a whole tile,” he said.

“Precision ag specialists then bring that whole farm data back to paddock-by-paddock to make comparisons on crop growth, health and weed status.”

Both dryland and irrigation farmers have used precision agriculture during the drought to manage the concentration of water into drains, dams and waterways, and minimise crop losses in future to water logging.

Auto-steer application data is used to develop elevation maps and drainage plans.

McGrath said farms with sodic soils should consider surface drains and variable rate gypsum as a comprehensive surface water management strategy.

Precision Agriculture uses EM38 with RTK elevation data down to 2cm accuracy and at different swathe widths from 10 to 36m to design for strategic drains and paddock layouts.

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For those simply wanting a useful farm map, precision agriculture via satellite imagery can deliver GPS referenced farm maps for everyday use.

Accurate maps make life easy for calculating fence-line distances and arable areas, planning or giving out instructions for specific locations.

Maps can indicate paddock boundaries, internal fences, hazards, laneways, roads, water points, gates, plantations and assets.

There is no special software required for viewing the maps.

“Many people like the personalised maps with the hectares listed on them as costs can be calculated for contract spraying or sowing,” McGrath said.

McGrath said collecting data is useful, but knowing what to do with the data is the key.

“Operators need a farmer’s knowledge to background truth the data,” he said.

“Make sure you look at the science and background truth behind it to ensure what you are doing makes sense and is of benefit.”

McGrath advised growers to do their market research first before investing in precision ag technology.

“For a grower, it’s about what suits them best at the time, their budget and what they want to gain from it, or it might be worth doing a small amount of investigation rather than going all out,” he said.

McGrath advised seeking help from a specialist.

“There are not a lot of people with that knowledge of being able to navigate through some of the data,” he said.

“Growers can do it themselves at the bottom end of the scale but employing a specialist who understands the technology and soil science can ensure what the grower is doing is effective.”

McGrath recommended growers research cloud based technologies for data storage and transfer. He said the grower owns the data, not the service provider.

“The issue is the lack of internet service in some areas to download the data,” he said.

“For wireless data transfer, a couple of bars of 3G is needed.

“Some growers set up their tractors with boosters for data transfer in black spots while others are happy downloading yield data onto a USB and passing it on to us.

“There are all different levels of service in precision ag and it’s effectively about what level is of value to your situation.”

The return on investment in precision ag technology is one of the most common questions asked by growers.

“A lot of the time the benefit will come in the harder years – in a good year moisture tends to mask a lot of problems in the soils,’’ McGrath said.

“When it comes to these dry years and growers have to be a lot more savvy, then they can see the benefits from the way they have managed their country.”

Here are McGrath's four top tips for growers looking into precision agriculture: