In the world of agriculture, Azolla, also known as “Mosquito fern” or “Duckweed fern,” stands out as a tiny but mighty player. This free-floating aquatic fern, characterized by its short, branched, floating stem and roots that penetrate into the water, belongs to the Salvinaceae family. In this article, we’ll delve into the fascinating world of Azolla and explore how it has become a game-changer for farmers, particularly in the tropical regions of India.
Agriculture has seen various revolutions, and one such revolution in India, known as the Green Revolution, led to the adoption of high-yielding rice varieties. While this significantly increased agricultural output, it came with a trade-off. The new rice plants were shorter in stature, resulting in a lower straw-to-grain ratio. This, in turn, reduced the availability of straws for cattle feed, posing a serious challenge for cattle farmers.
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What is Azolla?
Azolla thrives in fresh water, and you can also find it in moist soils and marshy pond lands. Its presence is particularly widespread in the tropical regions of India. This fascinating fern is known by various names, including Mosquito fern, Duckweed fern, and Azolla. Azolla’s distribution spans a wide range, but it’s most commonly found in tropical regions, making it a valuable resource for farmers in these areas.
Azolla’s Role in Agriculture
1. The Green Revolution in India
The Green Revolution brought about a significant increase in rice production. However, it also presented a challenge. With shorter rice plants, there was less straw available for cattle feed, which threatened cattle farming. This is where Azolla came to the rescue.
2. Livestock Feed and Biofertilizer
Azolla isn’t just a solution for cattle feed; it’s also a biofertilizer for wetland paddy cultivation. This multifaceted fern fixes atmospheric nitrogen through a symbiotic relationship with blue-green algae (Anabaena azolle). What’s more, it offers high nutritional value.
Azolla’s Unique Features
1. Leaf Structure
Azolla’s leaves are unique, with green, thick, aerial dorsal lobes containing chlorophyll and larger, slightly thinner, floating ventral lobes. This distinctive structure gives Azolla a reddish-brown appearance due to the presence of anthocyanin pigment.
2. Size and Appearance
Azolla comes in various species, with Azolla pinnata ranging from 1-2.5 cm and Azolla nilotica growing up to 15 cm in size. Its floating, triangular or polygonal appearance is visually striking.
3. Symbiotic Relationship
The most fascinating aspect of Azolla cultivation is its symbiotic relationship with the nitrogen-fixing blue-green alga, Anabaena azollae. Azolla creates a protected cavity inside each leaf to store atmospheric fixed nitrogen and potentially other growth-promoting chemicals.
Nutritional Value of Azolla
Azolla’s nutritional value is impressive. On a dry matter basis, it contains:
The Beneficial Effects of Azolla
In a world where sustainable agriculture and environmental consciousness are becoming increasingly vital, Azolla, often referred to as the “green gold,” emerges as a fascinating and multifaceted solution.
This small aquatic fern packs a powerful punch when it comes to benefits in livestock feeding, bioremediation, biofertilizer production, weed control, mosquito management, and even the production of biogas. In this article, we’ll delve deep into the numerous advantages of Azolla and its potential applications, from enhancing livestock health to its contribution to a cleaner and more sustainable future.
1. Nutrient-Rich Feed for Livestock
Azolla is a powerhouse of nutrition, containing high levels of protein, amino acids, vitamins (A, B12, Beta Carotene), and minerals. Its low lignin content makes it an ideal feed for animals. When incorporated into the diet of poultry birds, Azolla has been shown to enhance broiler chicken weight and increase egg production in layers.
The benefits extend to other animals like sheep, goats, pigs, rabbits, and fish, with notable improvements in milk production for milch animals, meat yield for goats, and egg-laying capability in poultry.
2. Climate Change Adaptation for Livestock
As climate change poses challenges to livestock production by affecting the quality and quantity of feed crops, Azolla pinnata emerges as a promising solution. This unconventional protein supplement for cattle, particularly in rain-fed areas, provides a lifeline for livestock during lean periods. It offers adaptive capabilities for farmers to cope with the changing climate and ensure the well-being of their animals.
3. Bioremediation: Nature’s Cleanup Crew
Azolla’s remarkable abilities go beyond the barnyard. This versatile fern, along with Lamna minor, has the capacity to remove heavy metals like iron and copper from contaminated water. It can directly concentrate metals and nutrients from polluted or sewage water, contributing to environmental cleanup efforts and water quality improvement.
4. Biofertilizer: Boosting Rice Yield
Azolla has a unique ability to decompose rapidly in soil, ensuring maximum nutrient availability to rice plants. This characteristic makes it an excellent source of biofertilizer and green manure. Its application in rice fields can lead to a significant increase in rice yield, often in the range of 20-30%.
5. Natural Weed Control
One of Azolla’s hidden talents is weed control. With its dense covering, this aquatic fern acts as organic mulching in rice fields, effectively preventing weed growth. Additionally, it helps retain soil moisture, reducing evaporation rates. Studies have shown that Azolla cover significantly reduces weed infestations, especially the dominant weed Monochoria vaginalis.
6. Mosquito Management: A Natural Barrier
Azolla’s role extends to pest control, particularly in inhibiting mosquito breeding. This fern creates a dense mat on the water’s surface, thwarting mosquito hatching and adult development. It serves as a natural and eco-friendly method to combat mosquito-related issues.
7. Green Energy from Azolla: Biogas Production
Azolla’s potential in energy production is remarkable. During the anaerobic fermentation of Azolla, methane gas is generated, which can be used as a fuel source. The effluent left behind is rich in nutrients and can serve as an excellent fertilizer. When combined with cow dung, Azolla residues increase gas production, making it a sustainable and eco-friendly energy source.
8. Azolla and Bioenergy: A Clean Energy Source
Azolla Anabaena, when grown in a nitrogen-free atmosphere and a water medium containing nitrate in the symbionts, produces hydrogen from water. This results in a clean, high-energy fuel that does not contribute to air pollution. Azolla’s potential in the bioenergy sector holds great promise for a greener future.
9. Medicinal Use of Azolla
Azolla finds applications in medicine, where it is used to prepare cough medication. Its potential in the pharmaceutical industry is an exciting area of exploration.
10. Azolla as a Human Food Source
While Azolla is commonly used as livestock feed, it holds untapped potential as a human food source. Rich in protein, essential amino acids, minerals, vitamins, and carotenoids, Azolla provides a nutritious option for human consumption, particularly in regions like India and East Asia.
11. Azolla as Part of Space Diet
Azolla’s adaptability extends beyond Earth. Recent recommendations for including Azolla in the space diet have shown that it meets human nutritional needs, making it a potential food source for astronauts during space missions and habitation on other celestial bodies.
Azolla Cultivation: A Sustainable Farming Practice
Cultivating Azolla is an eco-friendly and economically sound approach that offers numerous benefits for both farmers and the environment. Azolla, often referred to as the “green gold,” can be grown through in-situ and ex-situ methods, making it a versatile solution for livestock feeding, biofertilizer production, and more. In this article, we’ll explore the step-by-step process of Azolla cultivation, its requirements, and its impact on agriculture.
Types of Azolla Cultivation
Azolla can be grown through two primary methods:
1. In-situ Azolla: This involves cultivating Azolla within the main field where other crops are grown. It’s an integrated approach that enhances soil fertility and provides supplementary feed for livestock.
2. Ex-situ Azolla: Azolla is grown outside the main field and then incorporated into the farming system. This method allows for controlled cultivation and easy management.
Azolla can also be cultivated in polythene bags using a specialized technique.
Azolla Cultivation Procedure
1. Selection of Pond Location
- Choose an area near your house for easy monitoring.
- Opt for a location with partial shade to reduce evaporation and support effective photosynthesis.
- Ensure a regular water supply.
- The pond’s floor should be free from stones or root debris to prevent water leakage.
2. Pond Size and Construction
- The ideal pond size depends on the number of species being grown and the available resources. Typically, Azolla can be cultivated in a 6 x 4-foot area.
- Clean and level the selected area.
- Construct the pond’s lateral walls using bricks or excavated earth.
- Lay a durable plastic sheet (such as silpauline) in the pond and secure the edges with bricks.
- Use a net to provide shade and prevent debris from falling into the pond. Support the shade net with thin wooden poles or bamboo sticks.
- Secure the plastic sheet and net with weights like bricks or stones around the boundaries.
3. Production of Azolla
- Fill the pond with a uniform layer of fertile sieved soil mixed with cow dung and water.
- Spread approximately 1 kilogram of fresh Azolla culture evenly in a 6 x 4-foot pond.
- Biogas slurry can also be used, and maintain a water depth of four to six inches.
- During the monsoon season, collect rainwater from rooftops for Azolla cultivation.
- Be cautious about water salt content, as high salt levels can affect growth.
4. Maintenance of the Pond
- Apply 1 kilogram of cow dung and 100 grams of superphosphate every two weeks to support Azolla growth.
- Regularly remove trash and aquatic weeds from the pond.
- Replace the culture with fresh Azolla every six months.
5. Azolla Harvesting and Livestock Feeding
- Azolla takes two to three weeks to develop, depending on initial culture, nutrition, and environmental conditions.
- Harvest it daily once fully developed.
- Biomass can be collected using plastic sieves, with a 6 x 4-foot area producing approximately 850 to 900 grams of fresh Azolla daily.
- Azolla can be fed to livestock, either fresh or dried, directly or in combination with concentrates. Rinse it with fresh water to remove any cow dung odor.
- About 8-10 metric tonnes of Azolla’s green mass can be converted into 25-30 kilograms of nitrogen gas, yielding 55-66 kilograms of urea.
Economics of Cultivation
The cost of preparing a 6 x 4-foot pond is less than Rs. 500, including sheet and labor costs. Azolla cultivation can lead to additional fish production and reduced reliance on feeding concentrates, resulting in a net profit of over Rs. 4,500 per year for a farmer.
Requirements for Azolla Growth
- Water: Fresh, moving water at a height of 10-15 cm is essential in the reproduction pond, maintaining a water level of 4 inches for optimal growth and production.
- Temperature: Diurnal temperatures between 32°C and 20°C are ideal for Azolla growth. It thrives in partial shade.
- Relative Humidity: A relative humidity range of 85-90 percent is optimal.
- Soil pH: Azolla prefers slightly acidic soil with a pH of 5.2 to 5.8.
- Nutrition: As an N-fixing fern, Azolla doesn’t require nitrogen-containing fertilizer. Phosphorous concentrations of 20 kg/ha are desirable for biomass production.
Important Tips for Growing Azolla
- Maintain Azolla biomass at 300-350 grams per square meter to prevent overpopulation.
- Enhance Azolla’s mineral content by applying Super Phosphate and cow dung every five days, along with a weekly mixture of magnesium, iron, copper, sulfur, etc.
- Replace 25-30% of the pond’s water with fresh water every 10 days to avoid nitrogen accumulation.
- Every six months, completely change the water and dirt, and replant Azolla seeds.
- Maintain the water level at least 10 centimeters above the Azolla roots for easy harvesting.
- Carefully wash harvested Azolla to eliminate any remaining dirt or cow dung odor before feeding it to animals.
As the demand for food increases without compromising soil health and environmental integrity, Azolla emerges as an effective solution. Its role as a biofertilizer in rice-based intensive cropping systems, its weed suppression abilities, and its potential as a livestock feed offer numerous benefits.
Scaling up Azolla cultivation through government-supported rural and agricultural development programs can lead to a greener and more sustainable agricultural future, benefiting both farmers and the environment.
Azolla cultivation has already shown promising results, and it offers small-scale farmers a cost-effective and sustainable way to provide nutritious feed for their animals, increase milk production, and improve animal health. The potential benefits of Azolla are undeniable, and its adoption in agriculture can pave the way for a more sustainable and productive future.