Transforming Rice Cultivation: The Role of Nanoscale Selenium
AMHERST, Mass. — The production of rice, a dietary staple for over 3.5 billion people globally, carries substantial environmental, climate, and economic repercussions. However, groundbreaking research led by scientists at the University of Massachusetts Amherst and China’s Jiangnan University may pave the way for a more sustainable approach. Their findings illustrate that nanoscale applications of selenium can significantly decrease fertilizer usage in rice cultivation while simultaneously enhancing crop yields, improving nutritional quality, increasing soil microbial diversity, and reducing greenhouse gas emissions. A new study published in the Proceedings of the National Academy of Sciences marks the first demonstration of these applications in real-world conditions.
The Need for Innovation in Agriculture
“The Green Revolution massively boosted agricultural output during the middle of the last century,” commented Baoshan Xing, University Distinguished Professor of Environmental and Soil Chemistry and co-senior author of the research. “But that revolution is running out of steam. We need to figure out a way to fix it and make it work.”
Key to the Green Revolution was the development of nitrogen-rich synthetic fertilizers, which significantly raised agricultural yields. Yet, these fertilizers come with high production costs, generate large amounts of carbon dioxide, and often wash away before they can be fully utilized by crops.
The Challenge of Nitrogen Use Efficiency
On average, crops utilize only about 40–60% of the nitrogen applied, a metric known as nitrogen use efficiency (NUE). For rice, NUE can plummet to as low as 30%, meaning that a staggering 70% of fertilizer applied may wash away into nearby water bodies, causing eutrophication, dead zones, and other environmental crises. This inefficiency translates to financial losses, with 70% of fertilizer expenditure effectively wasted.
Moreover, the application of nitrogen fertilizer can lead to increased emissions of greenhouse gases like methane, ammonia, and nitrous oxide, which exacerbate global warming. Additionally, the fertilizer production process itself is carbon-intensive.
Discovering a Sustainable Solution
“Everybody knows that we need to improve NUE,” said Xing. “The question is how?”
The research team, including lead author Chuanxi Wang and senior author Zhenyu Wang of Jiangnan University, found that nanoscale selenium—an essential element for both plant and human health—can be effectively sprayed on rice foliage and stems to enhance nutrient absorption. This method reduced the detrimental environmental impacts of nitrogen fertilization by 41% while increasing economic returns by 38.2% per ton of rice compared to conventional practices.
Methodology and Findings
“We used an aerial drone to lightly spray rice growing in a paddy with a suspension of nanoscale selenium,” explained Wang. “This direct application means that the rice plant can absorb the selenium far more efficiently than if it were applied to the soil.”
The nanoparticles boost the photosynthetic activity of the rice plants, leading to a more than 40% increase in photosynthesis. Enhanced photosynthesis enables the plants to absorb more CO2, converting it into carbohydrates that help in root development. Robust roots release organic compounds that foster beneficial soil microbes, which then collaborate with rice roots to absorb more nitrogen and ammonium. This improved nutrient uptake enhances NUE from 30% to 48.3% and significantly reduces nitrous oxide and ammonia emissions by 18.8–45.6%.
Positive Impact on Yields and Nutrition
With an improved nutrient intake, rice crops not only achieve higher yields but also produce grains that are more nutritious, showing increased levels of protein, essential amino acids, and selenium.
A Future for Sustainable Rice Farming
Most remarkably, the findings indicate that these nano-selenium applications allow farmers to cut nitrogen fertilizer usage by 30%. Given that rice cultivation accounts for 15–20% of global nitrogen use, this new technique holds significant promise in addressing the challenges posed by a growing population, climate change, and escalating economic and environmental costs in agriculture.
