Plasma Agriculture

Dr. Katharina Stapelmann, assistant professor of nuclear engineering at NC State University
Excerpt from the IEEE Nuclear & Plasma Sciences Society,
Plasma Connection, December 2021

Plasma, also known as the fourth (4th state of matter, is an ionized gas consisting of electrons and ions (atoms/molecules that lose or gain electrons) as well as neutral reactive species. Plasma can be ignited in air by applying a very high voltage (on the order of tens of kilovolts) to electrodes. Air is (mostly) composed of nitrogen and oxygen and when the nitrogen and oxygen molecules interact with the high energetic electrons in the plasma, they can be dissociated and form reactive oxygen and nitrogen species by reacting with each other. This can also be observed in nature when molecular nitrogen (in the presence of oxygen) is converted to nitric oxide (NO) by lightning, a naturally occurring plasma. Indeed, plants have been observed to “green up” after first spring storms not only due to the water the thunderstorm brought but in particular due to the nitrogen compounds created by lightning that soak into the ground and create nitrates, an important fertilizer for plants.

Nitrogen Fixation–Fertilizer Production with Plasma

This effect of lightning can be recreated at room temperature by applying high voltage to air. An example of a plasma device to convert nitrogen from air into nitric oxides is shown in figure 2. The plasma is a dielectric barrier discharge (the pinkish glow) in direct contact with a water surface (above). Air is flown through the plasma and bubbled into the water to maximize the transport of nitrate into the water. The high voltage applied to the gap underneath the water accelerates electrons that can excite, dissociate, and ionize the surrounding gas. By using air, nitrogen and oxygen molecules are dissociated and form new species, providing the basis for nitrate (NO3-) which can be used by plants as fertilizer.

Full article is available here.

The IEEE Nuclear and Plasma Sciences Society (NPSS) originated in 1949 as the Professional Group on Nuclear Science within the IRE. At about the same time, the AIEE formed two committees, one on nucleonics, the other on nucleonic and radiation instruments. In 1963, the IRE and AIEE merged to form the IEEE. This resulted in the creation of the Nuclear Science Group. In 1972, Plasma Science was added and the group was promoted to a society. The NPSS is composed of eight technical committees, and a Transnational Committee, with a common interest in advancing nuclear and plasma sciences.