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I'm from a compost tech startup (Monty Compost Co.) focused on making composting more efficient for households and industrial facilities. But our tech isn’t just for composting— it’s a versatile system that can be repurposed for a wide range of applications. So, we’ve made it open source for anyone to experiment with!

One of the exciting things about our open-source compost monitoring tech is its flexibility. You can connect it to platforms like Raspberry Pi, Arduino, or other single-board computers to expand its capabilities or integrate it into your own projects.

Our system includes sensors for: * Gas composition * Temperature * Moisture levels * Air pressure

All data can be exported as CSV files for analysis. While it’s originally built for monitoring compost, the hardware and data capabilities are versatile and could be repurposed for other applications (IoT, environmental monitoring, etc.)

Hacker’s Guide to Monty Tech: https://github.com/gtls64/MontyHome-Hackers-Guide

If you’re into data, sensors, or creative tech hacks, we’d love for you to check it out and let us know what you build!

Hi!

Which manufacturer/model sensors are you using? I have made some environmental monitoring with very cheap sensors for some hobby projects, but have very bad experience on repeatability of the sensor reading, or for CO2 sensors even noise tolerance (was also dicussed on HN, that discussion made me realize that noise is the cause of the problems, and have managed to verify that).

I have some project ideas beyond my at-home breadboard prototyping but to go beyond I'd rather build on reliable components as the software/infra side is maturing now.

For Monty’s system, we use sensors from Bosch and Sensirion. During our initial prototyping phase, we tested around 20 different types of sensors and found they had the most workable results across a range of composting environments.

Feel free to share more about your project ideas— happy to dive deeper if it helps!

Thanks for posting!

Out of curiosity, could you talk more about the practical utility of the sensor readings you get while monitoring compost? Temp and moisture seem straightforward, but e.g., does gas composition imply anything about C/N ratio, or does it check if the pile is going anoxic? Is air pressure a general proxy for decomposition rate?

Also, have you changed any of your own composting practices due to what you’ve learned from your experience with monitoring?

To dive into the utility of the sensor readings-- The main gas we monitor is Total Volatile Organic Compounds (TVOCs), which act as a general proxy for decomposition activity. Combined with temperature data, this gives a strong indication of whether the activity is aerobic (a healthy compost pile) or anaerobic (not ideal and potentially smelly!). For example, a spike in TVOCs with decreasing oxygen availability often flags anaerobic conditions.

In terms of air pressure, this is used as part of our pile turn events detection in our companion app Monty Mobile. The app also analyses other data to assess how changes in conditions (e.g., moisture levels, turning frequency) affect decomposition. For most users, though, the general proxy is plenty— by identifying when a pile is “active” or “stalled,” they can tweak their process (e.g., adding browns, adjusting moisture, or aerating).

Compost is incredibly diverse, and the results will vary depending on the setup (tumblers, bins, worm farms) and inputs (manure, food scraps, garden waste). That said, 24/7 data from our system helps streamline the behaviour-change process. Rather than relying on a “try-wait-try-again” approach, users get immediate feedback, which can be a game-changer for both beginners and seasoned composters.

As for me, Monty has been a massive learning tool. Using the Monty Mobile app has personally helped me engage more with my compost pile and remember to add feedstock to adjust the pile when needed. It definitely makes me feel more in tune with what’s going on!

I hope this clarifies things! Happy to chat more :)

Adding to the main post--

You can check out the Monty Monitor here: https://montycompost.co/products/im-perfect-monty-monitor

I love it, but surely just a temp gauge for running a hot compost is nice & simple? If mine is over 45C, I'm fairly sure that means the thermophiles are present and doing their thing

You’re absolutely right— a temperature gauge is a fantastic tool for monitoring for many composters who are focused on the basics of maintaining an active hot composting pile.

Where our system shines is when you want to go a little deeper. For example, adding data on gas, moisture levels, and air pressure allows users to troubleshoot or optimise their process more effectively. Is the activity aerobic or anaerobic? Is your moisture level tipping the pile too far one way or another? These kinds of insights can help when composting setups or inputs get more complex, or when things stall and you’re not sure why.

That said, we totally get that not everyone needs all the bells and whistles—sometimes a reliable temp gauge and your composting instincts are all you need to make amazing, healthy compost!

How do you verify the expected metabolic processes are occurring that produce said temperatures?

Great question— thanks for asking!

Verifying the metabolic processes in composting is a bit of a mix between understanding composting fundamentals and interpreting the data we collect. The processes are highly dependent on factors like feedstock type and volume. For example, a sudden spike in temperature might be due to an addition of nitrogen-rich materials or a recent turning of the pile—both of which can accelerate microbial activity.

While our sensors provide 24/7 data on temperature, gas composition, and more, there are always factors we can’t directly see or control for, like the exact distribution of materials within the pile. That’s where a bit of interpretation comes in: matching what the data is telling us with the fundamentals of composting.

By combining real-time monitoring with an understanding of what’s happening in the pile, users can make informed decisions to keep their composting process on track. It’s not an exact science, but the extra data helps a lot!

Do you know if anyone is writing a HomeAssistant integration for this?

https://en.wikipedia.org/wiki/Home_Assistant for those like me who have never heard of this software

Not yet, but maybe you? :)

collectd is an open source monitoring system which can record to e.g. RRD flat files or SQLite and can forward collected metrics to SIEM-like monitoring and charting and anomaly detection apps like Grafana or InfluxDB.

Nagios has "state flaping detection" to prevent spurious notifications.

collectd-python-plugins includes Python scripts for monitoring humidity and temp with i2c sensors and Python: https://github.com/dbrgn/collectd-python-plugins

There are LoraWAN soil moisture sensors, but they require batteries or an in-field charging method

"Satellite images of plants' fluorescence can predict crop yields" (2024)

"Sensor-Free Soil Moisture Sensing Using LoRa Signals (2022)" https://dl.acm.org/doi/abs/10.1145/3534608 .. https://news.ycombinator.com/context?id=40234912

/? open source soil moisture sensor: https://www.google.com/search?q=open+source+soil+moisture+se...

Thanks so much for sharing these resources—this is fantastic!

If you’re into LoRaWAN, you might be interested to hear that we’re also developing an industrial composting monitor that incorporates LoRaWAN tech. Here’s the promo video link if you’d like to check it out: https://www.youtube.com/watch?v=TZFiiwLhZh8&feature=youtu.be

/? crop monitoring wikipedia: https://www.google.com/search?q=crop+monitoring+wikipedia ...

Precision agriculture: https://en.wikipedia.org/wiki/Precision_agriculture

Digital agriculture: https://en.wikipedia.org/wiki/Digital_agriculture

/? crop monitoring system site:github.com https://www.google.com/search?q=crop+monitoring+system+site%...

SIEM: https://en.wikipedia.org/wiki/Security_information_and_event...