A display in a field showing the water stress index over time

Hackaday Prize 2022: Using Infrared Thermometers To Measure Crops’ Water Stress

If you live anywhere on the Northern Hemisphere, you’re likely to have experienced one of the many heatwaves that occurred this summer. Extreme heat is dangerous for humans and animals, but plants, including important crops, also suffer. High temperatures lead to increased transpiration and evaporation, and if the water lost in this way is not replenished quickly enough, plants will stop growing and eventually wither and die.

In order to keep track of the amount of water available to crops, [Florian Ellsäßer] built the Crop Water Stress Sensor: a device that checks whether plants have enough moisture available to stay healthy. It does this by measuring the temperature of the leaves to calculate evaporation levels. If the leaves are cooler than their surroundings, this means that water is evaporating from them and the plant apparently has enough water available. If the leaves’ temperature is closer to the ambient temperature, then the plant may be running low on water.

[Florian]’s system performs this measurement using an infrared array, which is basically a low-resolution thermal camera that remotely measures the temperature of everything in its field of view. This IR array is pointed at a field, where it will see both leaves and the ground between them. The difference in temperature between these two can then be used to calculate the Crop Water Stress Index (CWSI), a standardized measure of how well-hydrated plants are. The result is shown on a display and also indicated using a convenient red-yellow-green status LED that shows if the crops in question need watering.

The system can be solar powered for completely remote operation, while its data can be read out through a WiFi interface. [Florian] is planning to update the design with a LoRa interface for greater range: the eventual goal is to build a large network of these sensors throughout agricultural areas and use the combined data to raise awareness of water shortages in certain areas. In order to make the sensors easy to build by anyone interested, all design files are available on the project page.

Keeping crops moisturized is one of the key tasks of agriculture, and we’ve seen several projects that aim to optimize and automate it, from a simple-but-effective ESP8266-based moisture sensor to complete hydroponics systems.

Agrivoltaics Is A Land Usage Hack For Maximum Productivity

Land tends to be a valuable thing. Outside of some weird projects in Dubai, by and large, they aren’t making any more of it. That means as we try to feed and power the ever-growing population of humanity, we need to think carefully about how we use the land we have.

The field of agrivoltaics concerns itself with the dual-use of land for both food production and power generation. It’s all about getting the most out of the the available land and available sunlight we have.

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Kotonki: Agricultural Vehicle Built For Customization

Agriculture on any scale involves many tasks that require lifting, hauling, pushing, and pulling. On many modern farms, these tasks are often done using an array of specialized (and expensive) equipment. This puts many small-scale farmers, especially those in developing countries, under significant financial pressure. These challenges led a South African engineering firm to develop the Kotonki, a low-cost hydraulically powered utility vehicle that can be customized for a wide variety of use cases. Video after the break.

The name Kotonki is derived from the Setswana phrase for a donkey kart. It is in essence a self-propelled hydraulic power pack, capable of hauling 1 ton of anything that can fit on its load bed. It comes in front-wheel drive or four-wheel drive versions, with each wheel individually driven by a hydraulic motor. The simple welded steel frame articulates around a double pivot, which allows it to keep all 4 wheels on the ground over any terrain. At a max speed of 10 km/h it won’t win any races, but neither would most other agricultural vehicles. The Kotonki is built mostly using off-the-shelf components and is powered by a common 12HP Honda engine. In the world of DRM agricultural equipment, this makes for simple repairs, low running costs, and easy customization for the task at hand. This can include mounting log splitters, water pumps, lifting beds, or anything else that can be driven by its hydraulic and rotary PTOs (Power Take-Off).

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Better Farming Through Electricity

Chinese researchers are reporting that applying an electric field to pea plants increased yields. This process — known as electroculture — has been tested multiple times, but in each case there are irregularities in the scientific process, so there is still an opportunity for controlled research to produce meaningful data.

This recent research used two plots of peas planted from the same pods. The plants were tended identically except one plot was stimulated by an electric field. The yield on the stimulated plot was about 20% more than the control plot.

The actual paper is paywalled in the journal Nature Food, but the idea seems simple enough. If you search for the topic, you’ll find there have been other studies with similar findings. There are also anecdotal reports of electrical plant stimulation going back to 1746.

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Would Nuclear Winter Cancel Out Global Warming?

Nuclear war was very much a front-of-mind issue during the fraught political climate of the Cold War era. Since then, atomic sabre rattling has been less frequent, though has never quite disappeared entirely.

Outside of the direct annihilation caused by nuclear war, however, is the threat of nuclear winter. The basic concept is simple: in the aftermath of a major nuclear war, the resulting atmospheric effects could lead to a rapid cooling in global temperatures.

Some say it couldn’t ever happen, while others – including Futurama – suggest with varying degrees of humor that it could help cancel out the effects of global warming. But what is the truth?

Hard data is isn’t really available, as thus far there have been  no large-scale nuclear wars for scientists to measure. Several studies have explored the concept of nuclear winter, however, and explored its potential effects.

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Human-Following Utility Trailer

[Théo Gautier] thought that a human-following utility trailer would be helpful for people working on farms. He didn’t just think about it, however, he designed and built it as a final project at the Agrilab FabAcademy at the University UniLasalle Polytechnique in northern France. He took the idea from concept to fruition in six weeks.

His build log documents the project very well, and takes you through his design choices and their implementation. The brains of the cart are a SAMD21E board that he made himself, and its sensory perception of the world is provided by HC-SR04 ultrasonic sensors and a PixyCam 2. Locomotion is provided by four each 100W DC motor / gearbox assemblies. He’s put a lot of effort into the construction process and posted a lot of photos of the intermediate steps. One piece of advice that caught our eye was to measure the diagonals of your frame repeatedly when welding it together — things can and do shift around. If you don’t, you may have to rectify the mistake like [Théo] did, with a big hammer.

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OpenCV And Depth Camera Spots Weeds

Using vision technology to identify weeds in agriculture is an area of active development, and a team of researchers recently shared their method of using a combination of machine vision plus depth information to identify and map weeds with the help of OpenCV, the open-source computer vision library. Agriculture is how people get fed, and improving weed management is one of its most important challenges.

Many current efforts at weed detection and classification use fancy (and expensive) multispectral cameras, but PhenoCV-WeedCam relies primarily on an OAK-D stereo depth camera. The system is still being developed, but is somewhat further along than a proof of concept. The portable setups use a Raspberry Pi, stereo camera unit, power banks, an Android tablet for interfacing, and currently require an obedient human to move and point them.

It’s an interesting peek at the kind of hands-on work that goes into data gathering for development. Armed with loads of field data from many different environments, the system can use the data to identify grasses, broad leaf plants, and soil in every image. This alone is useful, but depth information also allows the system to estimate overall plant density as well as try to determine the growth center of any particular plant. Knowing that a weed is present is one thing, but to eliminate it with precision — for example with a laser or mini weed whacker on a robot arm — knowing where the weed is actually growing from is an important detail.

PhenoCV-WeedCam (GitHub repository) is not yet capable of real-time analysis, but the results are promising and that’s the next step. The system currently must be carried by people, but could ultimately be attached to a robotic platform made specifically to traverse fields.