When you’re in a garden or a forest, you may have heard the sound of leaves fluttering in the wind or the wind chimes. But can you also hear the sounds of plants moving? Although too high or too low for human ears to detect, plants do hum with life. Virginia Tech researchers call it the “sound of plants dancing” and they are currently studying how it could help farmers in assessing plant health. This is particularly useful if farmers need to monitor their greens at an industrial scale.
Growing plant in a hydroponic environment
Lead researcher Bingyu Zhao, associate professor in the College of Agriculture and Life Sciences' School of Plant and Environmental Sciences, and team are now researching how the sonification of plant movements improve agriculture. “Imagine putting on a pair of headphones and being able to determine the health of plants based purely on what you hear,” Virginia Tech Daily published. If proven successful, it would be possible to make remote adjustments to fertilizer, water, or soil-based on what one hears, making sure plants grow healthily.
For their study, the researchers are focused on controlled-environmental or indoor agriculture, like greenhouses with LED lights or plants in hydroponic environments. Instead of using soil, they used liquid nutrient solutions. Zhao explained that when you grow a plant inside a building, you control introducing pathogens or insects by minimizing the use of pesticides. However, plants may sometimes have environmental stress or they could still have disease problems despite the control.
They found that plants that are growing in a healthy condition have a certain movement pattern. Yet, when a plant is stressed, such as it lacks light or the pH of the water dramatically changes, their movement pattern is also different. The team wanted to better understand the certain plant movement pattern and use such to reflect plant health.
How it could impact the global food source
The team believes that their work could impact the global food source by increasing the number of food-producing farms even in challenging growing areas, like urban environments. It will likewise increase the health of plants, thus enabling farmers to produce higher-quality or more food than before.
Last year, researchers from Tel Aviv University also found that tobacco and tomato plants made sounds at frequencies that humans cannot hear. However, when they placed microphones 10 centimeters from the plants, it picked up sounds in the ultrasonic range of 20 to 100 kilohertz. It is the kind of sound that some mammals and insects within 5 meters would be capable of hearing and responding. Plants make sounds when their stems are cut or they lack water. While they don’t have auditory systems or vocal cords, their process of making sound is called cavitation. During cavitation, air bubbles form, expand, and then explode in xylem, causing vibrations.
Micro-movements of plants develop patterns
For the Virginia Tech team, they set up high-resolution cameras to observe a small number of pepper plants. These cameras capture the movements of plants and over time, a pattern is developed. Although these movements are mostly unseen by the human eye, these micro-movements made by pepper plants become obvious when sped up in time-lapsed recorded videos. “Obviously, they can’t walk, but plants do shake,” the authors explained.
Then, the researchers used the data and convert it into sound, a process called sonification. This way, humans could already hear the patterns observed among plants. The purpose of the team why they used sonification is to eventually link particular sounds to indicators that a plant needs water or better light, for instance. After analyzing the data, computers can learn what is a good sound and what is a bad sound emitted by plants.
Zhao works with professors from different disciplines in the School of Performing Arts and in engineering to bring together several elements in the study. Susan Duncan, associate director of the Virginia Agricultural Experiment Station, also told Phys.org that the plant movement project is just a part of the new statewide SmartFarm Innovation Network.
Virginia Tech has brought together stakeholders in food processing fields and stakeholders from around Virginia, the US to hear their interests and concerns. A big takeaway during that meeting, Duncan said, is that technological innovation was on everybody’s mind. So, to catch up with the evolving needs in the industry and to maintain a future workforce, they needed to think beyond traditional techniques in agriculture. Thus, the meeting gave birth to the decentralized network, which comprised of 11 off-campus research centers. It even includes the Hampton Roads Agricultural Research and Extension Center in Virginia Beach.
The authors said that the center in their region may not be involved in the dancing plants project but it has plenty of areas of research, like boxwood blight disease and water quality. Virginia Tech researchers highlighted that over 100 research projects were linked to the network, probing into the future of agriculture.
Employment in agriculture
Our World in Data shows an overall decline in the total number of people employed in agriculture. In 2011, for instance, there were 2.79 million people in Japan in agricultural employment. Other countries highlighted include the US (1.96 million), UK (596,274.61), and Netherlands (252,394.44). Half of the world’s habitable land has also been used for agriculture.
Land use, measured in meters squared, required to produce 1,000 kilocalories of a given food product is detailed as follows: tomatoes (4.21 m²), bananas (3.22 m²), oatmeal (2.9 m²), citrus fruit (2.69 m²), peas (22.16 m²), nuts (2.11 m²), wheat and rye (1.44 m²), rice (0.76 m²), and maize (0.65 m²).
Urban and indoor agriculture has been gaining popularity because of the changing climate. A popular form of indoor growing is hydroponic agriculture as plants can grow in water and primarily without soil.
If the dancing plants project of Virginia Tech will be used on a large-scale, it could be easier for farmers to improve agriculture as the plants themselves are guiding them to make decisions for them. A specific sound could be interpreted whether they need more light, more phosphate, or more nitrogen. Farmers don’t even have to be in the building to check and adjust plant growth conditions.