Two recent developments highlight the increasing role of nuclear technologies in agriculture and food. First, in her budget speech on July 23, Finance Minister Nirmala Sitharaman said the government would provide financial support for 50 multi-product food irradiation facilities.
Second, the International Atomic Energy Agency (IAEA) organised the IAEA Scientific Forum ‘Atoms4Food’ in September. Speakers from different countries described how nuclear technologies were being used in agriculture and food production back home.
From India, Satyendra Gautam, Head, Food Technologies Division, Bhabha Atomic Research Centre (BARC), told the audience that BARC had developed 62 improved varieties in 12 different crops, and the country boasts two major irradiation facilities at Vashi and Nashik respectively.
Most participants spoke in the same vein — the Malaysian representative about rice and the Jamaican about ginger, for example.
When people talk of nuclear technologies in agriculture and food production, it is always about irradiation. Irradiation for ‘radiation-induced mutagenesis’, or the use of radiation to bring about desired characteristic changes at the gene, chromosome or DNA level. Or irradiation used to kill microbes that cause rotting and thereby extend the shelf life of agricultural produce.
However, there are many more nuclear technologies out there waiting to be used in agriculture.
Here are some examples of nuclear technologies that can be deployed in agriculture to ensure food security:
Fallout radionuclide (FRN) technique: You can tell the occurrence and extent of soil erosion by analysing radionuclides. A nuclide is a specific isotope of an element (example Cesium-137); a radionuclide is the nuclide of a radioactive element.
Radionuclides bind themselves to the soil and move with the soil. By taking soil samples at different locations and depths, scientists can measure the concentration of these radionuclides.
Areas with high radionuclide levels indicate soil accumulation while areas with lower concentrations suggest soil erosion. FRN technique “offers a distinct opportunity to quantify soil erosion rate and understand erosion processes in the landscape in a comprehensive manner,” say Suresh Kumar et al, authors of a paper on using FRN for measuring soil erosion in the Himalayas.
The authors, from the Indian Institute of Remote Sensing and the Indian Institute of Soil and Water Conservation, both in Dehradun, say the FRN technique “offers a reliable, cost-effective, and long-term measurement of soil erosion rates, making it a valuable tool for soil ecosystem management.”
Cosmic-ray neutron sensor (CRNS) technology: It is known that some farmers bury sensors in the soil; these sensors continually transmit moisture levels in the soil, helping the farmer decide when and how much to irrigate.
CRNS is a simpler alternative to determine the moisture content over a vast field, say, 20 hectares. Cosmic rays are high-energy particles that roam in space. Some of them enter the earth’s atmosphere, where they collide with atoms of atmospheric gases. These collisions generate secondary particles, including fast-moving neutrons.
These neutrons scatter and penetrate the soil, where they interact with the hydrogen atoms in the soil moisture. Since moist soil absorbs more neutrons, the number of neutrons that escape back into the atmosphere is less. Dry soil reflects more. The cosmic ray neutron sensor detects the number of neutrons, by which you can tell the soil moisture levels.
Though CRNS is said to be mainly used to measure soil moisture content over a large area, a group of Chinese scientists have suggested in a paper that it is possible to also use it for detecting moisture at desired points, such as roots. This is done by adjusting the sensor’s placement and footprint.
Radioimmunoassay (RIA) technology: RIA can be gainfully employed in animal reproduction. This is a technique in which a radioactively labelled version of a target molecule, such as a hormone, is injected into the animal. An antibody can bind to either the natural or the radioactively labelled version. RIA can be used to monitor critical reproductive hormones, such as progesterone, estrogen and luteinising hormones.
By detecting hormonal changes in animals, RIA can help in determining the optimal time for artificial insemination. The technique can also help improve fertility by identifying reproductive issues in animals, such as irregular hormone levels.
Sterile insect technique (SIT): This is an ingenious way of controlling pests. SIT involves mass rearing of the target insect, sterilising it to kill the reproductive cells and releasing it into the wild, where it competes with the natural insects for mating. When they mate, they do not produce offspring. The insect population goes down.
Other uses of nuclear technologies in agriculture include nitrogen-15 used to measure nitrogen fixation in roots and avoid unnecessary use of fertilizers; isotropic tracing techniques for crop nutrition and water management; and nuclear methods of analysing food authenticity and verifying geographic origins.
While many of these techniques are proven, they have not come into widespread use — certainly not in India — yet.