Azolla: Solution for fluctuating fertilizer market

Farmers are most vulnerable

Dr. Pham Gia Minh is the translator of the Vietnamese edition of The Azolla Story: A Message from the Future by two British scientists, Jonathan Bujak and Alexandra Bujak, and has helped popularize the book and inspire interest in it.

According to him, amid conflicts in the Middle East that are causing strong fluctuations in the global fertilizer market, the use of natural nutrient sources such as azolla (duckweed fern) is increasingly being viewed by experts as an ecological solution. It can help reduce costs, improve soil quality, and lower greenhouse gas emissions.

Meanwhile, rice cultivation practices in Viet Nam still depend heavily on chemical fertilizers, making farmers highly vulnerable when fertilizer markets fluctuate sharply due to political factors, energy crises, or climate change. This highlights the need to seek more sustainable production solutions that reduce dependence on imported inputs.

In the past, azolla was a familiar component of rice field ecosystems in northern Viet Nam. According to agricultural literature, this aquatic plant once covered more than 1.5 million hectares of rice fields and contributed to yields of 5-7 tons per hectare even during periods of limited chemical fertilizer use.

Azolla has a symbiotic relationship with the cyanobacterium Anabaena azollae, which enables it to fix atmospheric nitrogen and convert it into nutrients for rice plants. As a result, using azolla in rice cultivation can significantly reduce the amount of chemical nitrogen fertilizer required.

In the current context, as agriculture shifts toward ecological models and greenhouse gas emission reduction, re-evaluating the value of traditional farming practices such as azolla use is essential, especially when combined with modern agricultural technologies.

Benefits for the nation and for individual farming households

According to research and field trials on rice cultivation in Viet Nam and several Asian countries, using azolla can reduce urea fertilizer use by around 30% while maintaining stable yields. Assuming an average nitrogen application rate for rice of about 120 kg N/ha (equivalent to approximately 260 kg of urea/ha) and a urea price of around 10,000 VND/kg, current urea costs would be about 2.6 million VND/ha per crop.

With a 30% reduction in urea use through azolla application, farmers could save approximately 0.78 million VND/ha per crop. If applied across 1 million hectares of rice, total fertilizer cost savings could reach around 780 billion VND per crop season. This is a significant figure in the context of rising agricultural input costs.

Beyond reducing fertilizer expenses, the use of azolla can also help reduce greenhouse gas emissions in rice farming. The presence of azolla on the water surface can reduce methane emissions by about 20-40%. With average rice field emissions of around 1.2-1.5 tons CO2e/ha per crop, a reduction of about 30% could translate into a decrease of 0.36-0.45 tons CO2e/ha per crop.

With voluntary carbon credit prices at around USD 10 per ton of CO2e, the potential value could reach approximately VND 100,000 per hectare per crop. If implemented across 1 million hectares, the potential revenue from carbon credits associated with azolla could amount to about VND 100 billion per crop. Notably, the carbon credit market based on nature-based solutions is showing strong growth. Some forecasts suggest that carbon credit prices from biological solutions could reach around USD 45 per ton by 2030.

Beyond direct economic returns, azolla also provides multiple ecological benefits for agricultural soils.

Apart from some mountainous areas where the ecological conditions in rice fields have been preserved and azolla still occurs naturally, there are currently several models cultivating azolla for medicinal use in Thai Binh and as feed for aquaculture in Ha Noi.

When decomposing in rice fields, azolla provides organic matter and essential nutrients, including N, P, K, and various micronutrients. Under favorable conditions, azolla can fix around 1,100 kg of nitrogen per hectare per year. As a result, soil fertility improves, soil structure is enhanced, and the need for chemical fertilizers in subsequent crops can be reduced by an additional 10-20%. This not only lowers costs but also lays the foundation for the development of organic and green agriculture.

Taking all direct economic factors into account, if the azolla model is implemented on 1 million hectares of rice per crop, the estimated benefits would include savings of VND 780 billion in fertilizer costs per crop and VND 100 billion in income from carbon credit sales per crop. If applied across two rice crops per year, the total economic benefit could reach approximately VND 1.58 trillion annually.

At the household level, for each hectare of rice cultivated with azolla, the additional benefit from reduced fertilizer costs could reach about VND 1.5 million per year (for two crops), not including the further 10-20% reduction in fertilizer use in subsequent seasons. In the context of continuously rising urea prices, along with unquantified benefits for soil health, crop quality, the living environment, and the branding value of organic rice, the use of azolla in rice cultivation is a solution that deserves greater attention.

Beyond economic value, restoring and developing rice farming systems integrated with azolla can deliver multiple macro-level benefits: reducing dependence on imported fertilizers, saving foreign exchange, contributing to Viet Nam’s methane reduction commitments at COP26, improving soil and water quality, and promoting the development of organic agriculture.

However, candidly speaking, for azolla to be widely adopted again, it is necessary to introduce policies supporting research on the mechanization and automation of cultivation and processing. This includes building gene banks and developing heat-tolerant azolla varieties suited to different soils and climate conditions across Viet Nam; establishing carbon credit markets for rice cultivation systems integrating azolla; forming cooperatives and companies specializing in azolla propagation services for farmers; and encouraging universities and agricultural research institutes to expand applied research on azolla in Viet Nam, alongside strengthening international cooperation in this field.

In the context of global agriculture facing increasingly unpredictable fluctuations, the effective utilization of available biological resources such as azolla could become an important pathway to enhance the self-reliance and sustainability of Viet Nam’s rice production system.

$1 = 26,357 VND (source: Vietcombank).