During our Shealy Farm Field Day, two of our students discussed the rotational grazing aspect of our research project. They also showed everyone the ultrasonic sensor that is attached to a John Deere gator used to measure the height of the grass in each paddock. This determines where the cattle need to be moved to.
We are using what is called an ultrasonic sensor to measure the height of the grass in each paddock to determine where cattle need to be moved to. This is an instrument that was developed by Mizzou and attached to the front of a vehicle of some sort. (We use a John Deere gator, Mizzou uses a four-wheeler.) The ultrasonic sensor uses sonar to measure the height 20 times a second. We take the average from each paddock and move the cattle to the highest average.
When looking at the average height measurements anything that reads below 75mm is considered to be undergrazed, 150mm-225mm is a good grazing height (when the cattle can be moved into the field), and anything above 225mm is considered overgrazed and immediate action would be needed whether it be moving cattle into that field, cutting the grass, etc. Farmers and ranchers usually use a grazing stick to achieve this same result, but the ultrasonic sensor is far more accurate.
The system also uses GPS to calculate the speed in which the vehicle is moving. This is important due to the fact that it needs to be moving at a speed of 5-15 kilometers/hr. The speed also needs to try to be as consistent as possible. When we drive it we try to maintain a speed of 9-10 kilometers/hr. The cost of this particular system, as of right now is $6800. Mizzou is working on a smart phone application that will drop the price of it significantly, but its still in the developing