It’s often said that the big opportunity in the Internet of Things (IoT) arena is not the really cool stuff around connected homes but the more mundane aspects of life, like street litter bins that self-monitor so that they are not emptied when they are only half full and at the other extreme, not filled to overflowing with rubbish spilling out on to the street.

In southern California, Kurt Bantle, a senior solution manager at IOT firm Spirent Communications, has been trialling an IOT solution to save on water consumption, in an area stricken by drought.

California produces 95 per cent of avocados grown in the US, almost all grown in Southern California, in a five-county region that straddles the coast from San Luis Obispo to San Diego. It takes 74 gallons of water to produce one pound of avocados, and like the rest of the state, the southern coastal region is locked in a drought and largely cut off from the flow of surface water from the states big irrigation projects. Avocado groves have been hit badly with sky-high water costs and reliance on water pumped from underground aquifers.

Water consumption is regulated in California, with the state entering its fourth year of drought, resulting in water regulators imposing sweeping and draconian restrictions on the use of water. The State Water Resources Control Board has even urged Californians to let their lawns die.

Some avocado farmers in California feeling the heat have turned to new methods in growing avocados such as higher density planting which enables some to produce twice as much fruit for the same amount of water.

Bantle has 900 young avocado trees planted in his “back garden” in southern California. Within his remit to develop Spirent’s IoT offering, he decided to look into the possibility of growing avocados using less water through soil moist monitoring and automated irrigation.

Bantle divided his farm into 22 irrigation blocks and inserted two soil moisture measurement units into each block. The units contain a LoRa unit for narrow band data communication to a LoRa gateway with broadband cellular uplink connectivity.

The gateway also contains a re-programmable SIM from Spirent partner, Oasis. This becomes the enabler in remote water provisioning. All soil moisture data is collected from the avocado trees into the cloud and visualised by a presentation layer.

When a tree needs to be watered, the solution turns the sprinklers on automatically to get the correct level of soil moisture for each tree. It then turns them off when the correct moisture levels are reached. The connected trees are monitored constantly day and night.

“Avocado trees typically take 4 acre feet of water per acre per year (1 acre foot = 326000 gallons). This is not only to supply the needed water, but also to leach the salts which build up in the soil,” said Bantle.

“The soil moisture sensors let me drastically reduce water usage by telling me when to water and how deep to water to push the salts past the bulk of the rooting zone. The majority of the roots are in the top eight inches of soi, so there is a sensor there and another at 24 inches, so I can see when I’ve watered deep enough to get the salts out of the rooting zone.

“The case study showed water usage reduction by 75 per cent, but the usage will climb as the trees get bigger. The goal is to reach a 50 per cent reduction of water usage when fully grown. By keeping the salts in check along with keeping nutrients supplied, stress on the trees is reduced and they are able to have better crop production,” added Bantle.

The downside for Bantle in harnessing the power of IoT to reduce water consumption was that he was placed under state surveillance for meter tampering…

The connectivity solution provided by Spirent together with its IoT ecosystem partners for avocado trees applies to every type of vegetable and fruit farming including almonds, olives, apples, oranges and tomatoes.

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