Text and Photos by Henrylito D. Tacio
In the 11th century, farmers in the Kingdom of Dai Viet grew the dinky water fern in their rice fields. They did not know about nitrogen – the most critical requirement for plant growth – but they knew the fern made their rice grow better.
During the 14th century, farmers in the Kingdom of Cathay raised and sold the fern as feed for swine and ducks.
For hundreds of years, the descendants of those ancient Vietnamese and Chinese farmers used the water fern – now known as Azolla – to fertilize their crops and feed their livestock. Today, Azolla cultivation is spreading to other Asian countries, including the Philippines.
“Any rice plant, modern or traditional, requires one kilogram of nitrogen to produce 15 to 20 kilograms of grain,” said the International Rice Research Institute (IRRI) based in Los Baños, 60 kilometers south of Manila. “Most tropical soils imbibe sufficient nitrogen naturally to grow about one ton or 1.5 tons of rice per year. To augment yields above that, nitrogen must be provided.”
In the 1960s, petroleum-based fertilizers were the most economical practices to add nitrogen to the soil. “But fertilizers are expensive and we are increasingly aware of environmental pollution caused by improper fertilizer use,” says Jethro P. Adang, the Mindanao Baptist Rural Life Center (MBRLC) Bansalan, Davao del Sur, about 86 kilometers away from Davao City.
The air around rice is 80 percent nitrogen. Anabaena azollae, a blue-green alga that thrives in Azolla leaves’ cavities, can fix or draw nitrogen from the air. Azolla floats on the water between rice plants. When it dies and is incorporated into the soil, decomposition releases the nitrogen.
“Farmers who grow azolla are actually growing their own fertilizers,” Adang says. Azolla contains 4 percent nitrogen on a dry weight basis (dry weight is 5 percent of fresh weight), 0.5-0.9 percent phosphorus, and 2-4.5 percent potassium.
For only three hours, Adang claims, a farmer can grow adequate Azolla to increase yields equivalent to that produced by 30-60 kilograms of nitrogen fertilizer per hectare. Residual soil nitrogen is increased.
“Azolla growth does not interfere with normal rice cultivation,” IRRI assures. “In fact, it helps control weeds and improves soil texture.”
The use of Azolla as a fertilizer was first promoted in the Philippines in the early 1980s. Studies show that rice yields in plots with Azolla were higher than those without by more than a ton in the same cropping period.
One of the prime movers of Azolla technology in the country in those years was Mamerto Fantilanan, who “Inilusan” (a local word for “the place where people share”) farm in Capiz province, was more than just a profitable venture in a rural community where small farms were considered synonymous with poverty.
According to an article in a magazine published by the UN Food and Agriculture Organization (FAO), from his 7,000-square-meter farm, Fantilanan netted annual income more than twice those of nearby farmers with four times as much land. Instead of using commercial fertilizer, he used Azolla.
“Organic farming is a matter of giving back to nature what you take from it,” Fantilanan was quoted as saying. “It is safe, economical, profitable, and logical.”
Fantilanan used Azolla to fertilize rice, vegetables, fruit trees, seedlings, and other cash crops. He also used Azolla as feed for his ducks, chickens, and swine. The family also ate Azolla since his wife served tasty Azolla burgers and omelets.
“Azolla makes the soil more fertile while improving its texture and acidity value,” Fantilanan said. In addition, his continuous use of Azolla minimized land preparation work. He didn’t plow the field; instead, he merely pushed with his feet the rice stubbles and Azolla into the soil. Then, he leveled the land with a harrow or rake.
Fantilanan planted rice seedlings using the double-row scheme. The distance between hills was 20 centimeters and one meter between each pair of rows. “With this substantial space, I raise enough azolla both for my rice crop and for my other projects,” he pointed out.
Unlike other farmers, he didn’t spray chemicals on his rice crop. An advocate of Integrated Pest Management (IPM) – a concept that maximizes farm profits and stresses insect and disease control with minimal pesticide use – he said that “friendly insects” took care of the pests on his farm.
“When my neighbors spray chemicals, the pest in their fields transfer to my farm,” Fantilanan reported. “But they don’t stay long – how can they, when they see all the spiders and beetles waiting to devour them?”
With the popularity of organic farming these days, the Department of Agriculture and other government agencies, policymakers, and farmers themselves should take a closer look at Azolla. “It’s high time to rediscover the many potentials of azolla,” urged Adang.
“Its high productivity associated with its ability to fix atmospheric nitrogen makes azolla an excellent green manure,” FAO said in a statement. “Its chemical composition makes it an important source of food for various livestock and special cultural practices made it possible to benefit simultaneously from its nutritive and fertilizing qualities, not to mention many other interesting properties of azolla.”
If composted alone, decomposition of Azolla takes about two weeks. The Philippine Recommends for Organic Fertilizer Production and Utilization shares this procedure on how to do it: “Dig a pit and pile the azolla to the rim, or pile on the soil surface with bamboo fencing. Cover with banana leaves or plastic to prevent drying. Harvest in about two weeks. The recovery is 7-15 percent of the fresh weight.”
Aside from being a good source of nitrogenous fertilizer, Azolla can also be used to feed livestock. Azolla is very rich in proteins, essential amino acids, vitamins (vitamin A, vitamin B12, and Beta- Carotene), growth promoter intermediaries, and minerals like calcium, phosphorus, potassium, ferrous, copper, and magnesium, among others. On a dry weight basis, Azolla contains 25-35 percent protein, 10-15 percent minerals, 7-10 percent of amino acids, bio-active substances, and bio-polymers. The carbohydrate and fat content of Azolla is very low.
But Azolla has limitations, too. Azolla culture essentially needs manual labor. Chinese scientists say it requires a lot of work, 24 to 33 man-days per hectare, to produce 40 kilograms of nitrogen. It also requires a rather detailed management system unfamiliar to most rice growers.
Furthermore, Azolla must be propagated vegetatively in water year-round. “Azolla is particularly sensitive to a water shortage,” says Dr. Charles Van Hoe, one of the world’s leading experts on Azolla. “Without water, the plant dies within a few hours.”