Agriculture developed about 10,000 years ago in the Fertile Crescent of Iran and Palestine, soon after the huge climatic changes marking the end of the last ice age.
Rice cultivation also began in central China near the Yangtze River over 8500 years ago in communities that domesticated pigs and water buffaloes (Smith, 1995).
It may even be as old as the earliest known agriculture recorded in the Fertile Crescent. It is an amazing thought that farmers in the Yangtze River valley may have been growing rice continuously, year after year, generation after generation, for ten thousand years with rice farmers using azolla as a green fertilizer for most of this time.
It is probable that azolla’s use as a green fertilizer for rice also dates back thousands of years as the link may have been quickly established by the early farmers. Azolla is endemic to the regions and wild azolla plants growing in the area would have naturally infested the water used to grow rice plants.
It would not have taken long for farmers to see that rice production increased whenever azolla grew in the same water as their rice plants.
Subsequent generations would then have introduced azolla as an integral part of their cultivation of rice, slowly perfecting the technique by trial and error.
These early farmers used a natural biological system to fertilize the rice; they used azolla’s ability to draw down nitrogen from the atmosphere, which then biofertilized the growing rice plants.
We know for certain that rice farmers used azolla as a rice biofertilizer 1500 years ago. The earliest known written record of this practice is in a book written by Jia Ssu Hsieh (Jia Si Xue) in 540 A.D on The Art of Feeding the People (Chih Min Tao Shu). By the end of the Ming Dynasty in the early 17th century, Azolla’s use as a green compost was being recorded in numerous local records.
The Spread of Azolla-rice cultivation
The knowledge that azolla increased rice production was mostly disseminated by Buddhist monks travelling through the Far East.
The use of azolla in rice production use dates back at least a thousand years in Vietnam. Some legends say that its cultivation was introduced by the Buddhist Monk Khong Mirh Khong in the eleventh century (Doa & Tran, 1979; Moore, 1969). Others say that ‘Beo Giong’ (azolla) was discovered and domesticated by a village women called Ba Heng (Lumpkin & Plucknett, 1980). Both stories may be true, as well as others that are lost in time, but we do know that azolla is revered as a green rice fertilizer.
Temples and wooden idols associated with azolla can be found in several villages, commemorating either Khong Mirh Khong or Ba Heng, whilst others, such as Bich Du, celebrate an annual festival to azolla.
Vietnamese rice farmers had to travel each year to villages such as Bich Du so that they could buy new azolla stock called ‘Beo Going’ for starter colonies because their own plants perished each year.
Only a few families knew the secret of maintaining and multiplying ‘Beo Going’ during the hot summer months, maintaining their monopoly of the azolla inoculum by guarding their secrets through a system of inheritance. This restricted azolla’s use in Vietnam to provinces such as Nam-Dinh, Hai-Duong and Hung-Yen that were close to villages with azolla inoculum.
In 1954 the government became interested in azolla’s potential to significantly increase rice production. More than a 100 depots were established to cultivate and distribute azolla inoculum, gradually extending its use throughout the country.
By 1973, Vietnamese rice-azolla cultivation had been established in half a million hectares, mostly in the northern part of the country:
Area of under azolla cultivation in northern Vietnam (Lumpkin & Plucknett, 1980)
1954: 5,000 hectares
1955: 40,000 hectares
1957: 90,000 hectares
1971: 300,000 hectares
1973: 500,000 hectares
Azolla’s use also expanded during the same period in China.
The plant was already being used in one and a half million hectares of rice production in 1962 when the Chinese Government set up a series of programs to improve its potential use as a rice fertilizer (Liu, 1979).
These programs helped to eliminate insect pests and also produced extra rice crops by extending its geographic range and length of the growing season. At the same time, the cold-tolerant species, Azolla filiculoides, was introduced from the U.S.A., a major advance that led to azolla’s use in the colder regions of northern China, as well as earlier in the year in southern China.
Azolla’s use as a biofertilizer is now widespread in rice cultivation throughout the Far East, including Bangladesh, Brazil, Burma, China, India, Indonesia, Korea, Nepal, Pakistan, Sri Lanka, Thailand, Vietnam and The Philippines.
As knowledge of its value spreads, Azolla is also being increasingly used in other regions of the world including West Africa (Kannaiyan & Kumar, 2005) and in South American counties such as Ecuador where its use is being promoted by Foundation Associate Mariano Montaño Armijo’s ‘Oryazo System‘.