Tracing the uptake of fertilizer
Fertilizer is necessary in modern agriculture to make plants grow. However, it is expensive and also causes environmental pollution: a large part of greenhouse gas and nitrogen emissions comes from natural or artificial fertilizers. The use of fertilizer can be reduced by adding radioactive isotopes, such as phosphorus-32. These isotopes are absorbed in the same way as non-nuclear isotopes of the same element. The radioactive isotopes decay over time. By measuring the decay radiation, one can trace which part of the fertilizer has actually been absorbed and how quickly, and which part has been lost.
Food irradiation
Radiation can also be used for food irradiation. A high dose of radiation kills bacteria and other pathogens, just like pasteurization, for example. In addition, radiation can prevent plants from germinating or ripening.
Because no high temperature is used, the chemical composition of the food does not change, which is an advantage over pasteurization. Also, no harmful chemicals are added to the food, such as preservatives. Because radiation is only used externally, and the radiation source does not end up in the food, irradiation is completely safe.
Insect control
Finally, radiation can be applied in pest control. In the so-called Sterile Insect Technique (SIT), large numbers of the pest are bred, sterilized using X-ray or gamma radiation, and released into natural populations. The pests – usually males – remain sexually active despite their infertility and compete with non-sterilized specimens for partners. This reduces their opportunities to reproduce.
The SIT is species-specific, so it is not harmful to species that do not need to be controlled. Additionally, SIT does not introduce new, foreign species into an ecosystem. Finally, the released specimens themselves cannot cause long-term damage by, for example, becoming a pest themselves, because they cannot reproduce.
This technique has been used against various species of fruit flies and the onion fly, among others. SIT has also been used against disease-carrying insects such as the tsetse fly and the malaria mosquito.
Ionizing radiation has many applications within the food industry. By means of radioactive isotopes, the uptake of fertilizer by plants can be investigated, reducing waste. Radioactivity can also be used to irradiate food, making it last longer. And through the sterile insect technique, harmful insects are controlled.