An Electronics Engineering student at the National University of Lesotho (NUL), Thabang Nkoko, has developed an intelligent machine that detects and kills weeds using lasers. Instead of using poisonous sprays to fight weeds in farmers’ fields, he is using a laser beam. The system is able to spot weeds and kill them one by one while it leaves the crops alone.
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Brought to you by NUL Innovation Hub [Where Academia Meets Industry] & MILCO [a store that sells only Lesotho products at Sefika Complex]. MILCO was founded by NUL Innovation Hub!
He worked on this exciting project under the supervision of Dr. Molef Makhele. And believe it or not, his idea works!
Let’s start with the basics.
What is laser. It is a very strong, focused beam of light that can cut, burn, or even heal things depending on how we use it.
And what are weeds? Well, if you’ve ever seen a garden full of vegetables, there are always some sneaky plants that grow in between. Those are weeds. They steal water, sunlight, and nutrients from the plants we actually want, like maize or beans.
Farmers spend a lot of time and money fighting weeds. The most common method? Spraying herbicides; chemicals that kill weeds. But here’s the catch: herbicides don’t just kill weeds, they also pollute the soil, flow into rivers, and sometimes even end up in the food we eat.
Worse, some weeds become resistant, meaning the chemicals no longer work. And the farmers? They have to spray more and more.
So the world is looking for new, safe, and sustainable ways to deal with weeds. That’s where Thabang’s invention steps in.
Thabang asked a simple but powerful question: What if we could kill weeds without chemicals?
His answer was to build a system that can see weeds and destroy them with laser beams. The setup looks like a small robotic car. On top, there’s a camera that constantly scans the field. The images are sent to a clever computer program called YOLOv12—short for “You Only Look Once, version 12.” This is one of the most advanced models for recognizing objects in real time.
And it works really well. The machine can tell a crop from a weed with 94.95% accuracy, and it does this at 27 frames per second, basically, faster than you can blink. As soon as the computer spots a weed, it sends a message to a microcontroller (a small electronic brain). The microcontroller turns on a laser beam, which fires for two seconds, burning the weed at its growing tip.
In trials, the system was able to completely kill weeds with a laser energy of 3.045 W/mm² in just one second. That’s like pointing a magnifying glass at a plant under the sun but way more precise.
If you think about it, this machine solves three huge problems at once:
1.The system reduces the use of herbicides. That means cleaner soil, safer food, and less pollution in our rivers and streams.
2.Manual weeding is hard work. Farmers can spend days in the hot sun, pulling weeds by hand, or paying workers to do it. This robot can cut labour costs by around 70%.
3.Unlike tractors that burn fuel or machines that disturb the soil, lasers don’t damage the land. They use very little energy, that is, about 0.5 kWh per hectare, which is five times less than mechanical weeding.
Of course, no new technology comes without challenges. Thabang noticed that sometimes weeds hide behind crops (a problem scientists call occlusion). When that happens, the camera struggles to spot them. He also found that small, soft weeds are easy to kill with a low-power laser, but big, woody weeds need stronger beams.
To deal with these issues, he suggests using 3D cameras, LiDAR sensors, or multispectral imaging in the future. That way, the robot won’t be fooled by shadows, tricky lighting, or crowded plants.
What makes this project even more exciting is how practical it is. Thabang’s prototype cost less than M1,500 to build. That’s much cheaper than fancy machines imported from China or America, which can cost hundreds of thousands of maloti.
And the system is modular, meaning it can be added to existing farm equipment. Imagine attaching this to a tractor or even a drone! Farmers could let it run over their fields, zapping weeds as it goes.
The work is built using open-source software like Roboflow, Ultralytics (for YOLO), and other tools. That means other students and researchers can improve on it without starting from scratch.
What does this mean for the future of farming in Lesotho?
It means farmers could grow crops without worrying about expensive herbicides. It means food could be safer and healthier. It means less pollution in the rivers and soil.
As Thabang put it: “This is not just about killing weeds. It’s about protecting the environment, cutting costs for farmers, and producing healthier food.”
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Brought to you by NUL Innovation Hub [Where Academia Meets Industry] & MILCO [a store that sells only Lesotho products at Sefika Complex]. MILCO was founded by NUL Innovation Hub!
