Know Before You Plant: Satellite IoT for Cotton in Australia

How direct-to-device IoT gets soil moisture readings out of cotton country with no cellular signal, what it costs, and who it is built to work with.

For a cotton grower, one number matters more than most: how much water the soil is holding. On most Australian cotton country there is no cellular signal, so a reading taken in the paddock stays in the paddock. Satellite IoT for agriculture is one way to get it out, using sensors built on open-standard LoRaWAN.

 

Cotton soil moisture monitoring in a cellular blackspot

Water decides most things in a cotton season, but the question changes with the system. Dryland cotton runs on the water already stored in the soil when the season starts. Irrigated cotton is watered on demand, and every irrigation costs water and pumping, so the question there is when to irrigate and when to hold off.

On dryland, CSIRO research presented at the GRDC Updates describes how stored water shapes the big calls in dryland cropping: whether to plant or wait, when to sow, and how much nitrogen to apply. A modelling study of six rainfed cotton sites in NSW and Queensland, published in Crop & Pasture Science, put a number on it. A high starting level of plant-available water added an average 1.31 bales per hectare compared with a low one.

The trouble is distance. Cotton enterprises commonly run from 1,000 to more than 4,000 hectares, and our analysis of the market suggests that 70–85% of dryland cotton land and 55–70% of irrigated cotton land sits in a cellular blackspot. That leaves two options: drive out and check by hand, or rely on experience and decide without a reading.

 

Where cellular coverage and LoRaWAN towers stop

Government programs such as the Mobile Black Spot Program are extending regional cellular coverage, but plenty of paddocks are still out of reach. Building your own LoRaWAN tower is another option. On dryland, across thousands of hectares of rotation fields, it is hard to justify on margins of roughly $400–$900 a hectare.

What cotton growers need is an off-grid farm sensor that can send its reading without a tower or a phone signal. That is what direct-to-device IoT does.

 

How does direct-to-device IoT work?

A direct-to-device sensor does not need a tower, a gateway or a phone signal. A small battery-powered node in the paddock picks up the reading from the soil sensor and sends it to one of our low Earth orbit (LEO) satellites as it passes overhead. From there it comes back down to the ground and lands in your dashboard, secure and encrypted. We call it collect, transmit, deliver.

The nodes use open-standard LoRaWAN with our LoneWhisper^®® radio technology, which is built for very low power, so a node can run for years on standard AA batteries. Satellite is there to extend the networks that already exist, not to replace them. The LoRa Alliance describes satellite-connected LoRaWAN as taking the same network out to the most remote fields, where terrestrial coverage ends. That means the same type of sensor can work on a farm network and out in the far paddock. The service works on Australia’s AU915 frequency plan.

We developed this with technical and financial backing from the European Space Agency, the UK Space Agency and Innovate UK. It already supports remote monitoring such as banana farms in Brazil and boreholes in Colombia.

 

What does soil moisture monitoring cost for cotton?

A typical dryland setup uses deep soil sensors that read stored soil water, plus small weather stations, at about one site for every 100–250 hectares. On a 3,000-hectare farm that comes to roughly 15–30 sites. Irrigated farms use more, because the answers change faster: removable multi-depth soil sensors, canopy sensors and channel height loggers, at about one site for every 20–50 hectares. On a 2,000-hectare irrigated farm that is roughly 40–100 sensors, plus channel loggers. In Australian dollars, typical costs look like this:

Item	Dryland cotton	Irrigated cotton
Sites	One per 100–250 hectares	One per 20–50 hectares
Hardware per site	$1,500–$2,500	$1,800–$3,000
Telemetry and software subscription	$2–$8 per hectare per year	$15–$35 per hectare per season
Gross revenue in a typical season	About $1,500–$2,500 per hectare	About $4,500–$6,500 per hectare

Even at the top of the telemetry range, that spend is under 1% of gross revenue per hectare in both systems. Our own plans are priced per connected device rather than per hectare, so what a farm pays depends on how many sites it needs.

 

LoRaWAN satellite connectivity in Australia

We have a Sentek soil sensor integrated with our connectivity as a working demonstration.

We are working with Farmers2Founders, an Australian agtech company, as our in-country business consultants.

Come and see it in Orange

You can find us at two events in Orange in October:

• The UK AgTech Showcase, at the Orange Ex Services’ Club. It is free, and you can register on the event page.
• The Australian National Field Days, on the Farmers2Founders site in Agtech Alley.

Come and see the integrated sensor working, and tell us what satellite coverage could mean for your blocks, your customers or your products. If you would rather talk first, book a 20-minute discovery call.

Want to read more? Have a look at how we approach remote grain monitoring, or explore our solutions.