Farm LoraWan irrometer sensors project

Hi Guys,

I currently have 9 irrometer sensors to measure the soil tension (kPa) in a sugar cane farm (see image). I am also taking these readings manually using a single arduino reader. So, each morning depending on the reading we decide if it’s time to irrigate the field.

I am new to the LoraWan tech, but I think this could be the best approach to take automatic readings, and we could display this data in a nice dashboard.

I want your advice in the setup I have in mind.

Gateway: WisGate Edge Max | RAK7249 Bundle 5 / 1pc 5.8dBi

The gateway will be placed were the marker is in the map. That is were we have the house and the Internet access.
About the installation of the gateway I have some questions:

Sugar Cane can get as high as 5 meters. The house isn’t that tall, so we are planing to install the gateway in a pole. Our farthest sensor is around 1.5km away from the house.

  1. How high do we have to install the gateway to get to a 1.5km away node?
  2. Is the 5.8dBi antenna enough? Or should I get the 8dBi. If I get the 8 dBi antenna, the recommendation is to install it with a feeder line cable which is 1.5m long. But I read that the longer the cable the higher the loss in dBi.

Nodes Arduino MKR 1310

The nodes will be placed in a IP67 case and will be powered using a battery. The idea is that the battery has to last for 13-15 months, so we only have to charge it once per harvest. These nodes will be placed in a pole, and the idea is to install the nodes at around 6 meters tall.

  1. Do I need and external antenna for each node? or can I use the antenna included with the arduino 1310 and install it inside de plastic case?

  2. Do I need to make these poles higher or is 6m enough?

Lora Server
I want to take readings every 15 minutes, and save them in to my database so I can make a dashboard with the data.

  1. Should I use TTN ? Or can the gateway send the data directly to a custom endpoint so I can consume the data as json in my own server?

Thank you for your feedback.


Especially if you elevate the gateway antenna about the house, it’s probably unecessary to elevate the node, as the cane stalks probably aren’t dense and wet enough to constitute a full obstacle.

Bu the easiest answer is to go out there with one node with integral antenna and try it.

Probably you want to try one node before you buy all of them anyway. In theory you could do a node-to-node test for ranging before investing in a gateway.

Note that true low power design is an art with near countless things which can go wrong; you’ll want to carefully validate your setup, or be prepared for the possibility that something that was supposed to last over a year dies in the initial attempt inside a month due to an overlooked leakage path.

Just for curiosity. Could you share the kind of irrometer that you are using? Does it provide a direct analog ( or digital ) signal representing the pressure? What are its power requirements: voltage, current.

We are using the WATERMARK Soil Moisture Sensors model 200ss. We use an Arduino Uno, and using a digital pin (5v), and an analog pin you can read the resistance of the the sensor. Which can then be converted to kPa using the formulas provided by irrometer. They also provide an example of making your own Soil Moisture reader here.

Chris, Thank you for your input. Yes, we plan to make some tests before buying all the equipment.