Azolla - Miraculous fern for nitrogen fixation & sustainable cattle feed

Azolla is a free floating fern and can be grown in ponds, pits, tanks, etc.

Azolla can be very easily cultivated in a pit with depth of 20cms.

Materials required:

• Azolla mother culture 250 g per sq m
• Labour for making trenches
• 5 kgs sieved soil per sq m
• Poly sheet 
• Poly net
• Few gunny bags
• Cow dung (4-5 days old) 1.5 kg per sq m
• Neem cake 125gm per sq m
• Water

Procedure:

Step 1: 

Azolla cultivation pit can be prepared using the following options

• Dig a trench
• Arrange bricks in a rectangle or square so that a pit is formed between the four sides
• Construct a concrete pit, in this case directly go to step 5

The pit should be 20 cms deep. Typically you can go for a pit with 2.5 x 1.5 x 0.2 m dimension. This will help in harvest and maintenance.

Have round edges avoid any sharp edge in the corners.

Step 2: 

Level the floor and remove any stones. There should be no slope inside the pit. 

Step 3: 

Place some gunny bags on the floor

Step 4: 

Cover the pit with UV stabalised poly sheet or tarpaulin sheet. Ensure that there is no wrinkle left. Also, the edges of the sheet should be well covered with soil so that the sheet remains tight and is not loosened when water is poured into the pit.

Step 5: 

Spread sieved soil on the floor evenly

Step 6: 

Make a slurry by mixing cow dung, neem cake & some water and sprinkle it evenly on the soil in the pit.

Step 7: 

Now fill the pit with water such that water depth of minimum 10 cm is achieved. Fill the water cautiously and ensure that the soil does not get concentrated in one corner or area.

Step 8: 

After the water is settled remove the layer of foam and scum that are formed. Now add the azolla mother culture to the pond. The Azolla mother  culture is nothing but azolla fern from some existing pit. This can be purchased from any existing azolla cultivator or from agriculture university.

Step 9:

Place poly net on the pit.

Harvesting:

Azolla will spread @ 400 g per sq m. Azolla will cover the entire bed and form a mat within 1 week. After 1 week the harvesting of Azolla fern can begin. Daily 400 g per sq m should be harvested this will avoid over-crowding of the fern.

Azolla should be harvested using sieved plastic trays. The fern should be washed properly in clean water two to three times to remove the cow dung smell. 

The left over water after washing (Azolla Wash) can be used as bio-manure for plants.

Usage:

Azolla can be used as cattle feed. The washed azolla should be mixed with feed concentrates in 1:1 ratio. 1 - 1.5 kg of azolla can be fed to the cattle every day. In case of excess, azolla can be dried and stored. This dried azolla can also be fed to cattle.

Dried azolla can be used as bio-manure in the farm. Azolla is a ver good source of nitrogen.

Notes:

1. It is important to keep azolla at the rapid multiplication growth phase with the minimum doubling time. Therefore biomass (around 200 g per square meter) should be removed every day or on alternate days to avoid overcrowding 

2. About 1 kg of cow dung should be added once every 5 days in order to maintain rapid multiplication of the azolla and to maintain the daily yield. 

3. The temperature should be kept below 25 °C. If the temperature goes up the light intensity should be reduced by providing shade. If possible, it is best to place the production unit where it is shady. 

4. The pH should be tested periodically and should be maintained between 5.5 and 7. 

5. About 5 kg of bed soil should be replaced with fresh soil, once in 30 days, to avoid nitrogen build up and prevent micro-nutrient deficiency. 

6. 25 to 30 percent of the water also needs to be replaced with fresh water, once every 10 days, to prevent nitrogen build up in the bed. 

7. The bed should be cleaned, the water and soil replaced and new azolla inoculated once every six months. 

8. A fresh bed has to be prepared and inoculated with pure culture of azolla, when contaminated by pest and diseases. 

9. The azolla should be washed in fresh water before use to remove the smell of cow dung.

Financial:

The cost preparing 1 pit of azolla of size 2.5 x 1.5 x 0.2 m is about Rs.1800/-. 

Overall cost of azolla harvest is Rs.0.65 per kg.