Azolla is a small floating aquatic fern that grows extremely fast and is high in protein. It can be grown in a shallow lined pit using very little water and no land of any value, and it is fed fresh to cattle, poultry, goats, fish and pigs.
For a smallholder livestock keeper, where bought concentrate feed is usually the largest running cost, it is one of the more useful things to have on the farm.
Setting Up the Bed
A practical size for a household with a couple of animals is around two metres by one metre.
- Dig a shallow pit, about 20 cm deep. Level the base and remove stones and roots
- Line it with a plastic sheet, taking the edges over the rim and securing them with soil or bricks. The sheet must be intact — a leak drains the bed
- Add sieved soil to a depth of a few centimetres across the base
- Add a slurry of cattle dung mixed with water, and a small quantity of mineral or rock phosphate mixture
- Fill with water to about 10 cm depth and let it settle for a day
- Introduce fresh azolla culture, spread evenly across the surface
Get starter culture from a KVK, an agricultural university or another farmer already growing it.
Siting
Azolla needs partial shade. Full direct sun in Indian summer conditions overheats the water and the culture dies off. A shade net, a thatch cover, or placement under a tree all work.
Site it near where the animals are, since you will be harvesting daily.
Daily Routine
Azolla roughly doubles in a few days under good conditions. Once established, it needs harvesting daily or it becomes overcrowded, turns brownish and stops growing.
- Harvest daily with a plastic sieve or fine net, taking a portion and leaving the rest to regrow
- Wash the harvested azolla in clean water to remove the dung smell before feeding — animals refuse it otherwise
- Top up water as it evaporates, keeping the depth steady
Weekly and Periodic Maintenance
- Add fresh dung slurry and mineral mixture at the interval advised for your setup
- Replace a portion of the water periodically to prevent nutrient build-up
- Every few months, empty the bed completely, clean it, and restart with fresh soil, slurry and culture
Beds that are never restarted eventually decline as salts and organic matter accumulate.
Feeding It
Introduce azolla gradually. Animals unfamiliar with it may refuse at first. Mixing it with the usual concentrate feed for the first several days gets them accepting it, after which most animals take it readily.
It is fed fresh, as a partial replacement for concentrate rather than a full substitute. The proportion it can replace depends on the animal, its production stage and the rest of the ration — get guidance from your veterinary officer or KVK for your specific livestock.
It also suits poultry, goats and fish, and it can be composted or used as a biofertiliser in rice fields.
Common Problems
- Culture turns brown and dies — usually too much direct sun, water too hot, or the bed is overcrowded because harvesting stopped
- Growth slows — nutrient depletion. Add fresh slurry and mineral mixture
- Insect pests — snails and some insects feed on azolla. Remove them manually
- Water level drops — a leak in the lining, or evaporation not being topped up
- Animals refuse it — usually inadequate washing. The dung smell is the issue, not the azolla
The Economics
The setup cost is small — a plastic sheet, some dung, mineral mixture and a starter culture. The running cost is almost nil beyond your daily labour.
The saving comes from replacing part of the bought concentrate feed. On a farm keeping two or three animals where concentrate is bought monthly, that saving accumulates steadily, and unlike most feed interventions it does not depend on land availability.
The main cost is the daily attention. A bed left unharvested for a week is usually a bed that has to be restarted, and this is why azolla units are frequently abandoned. It works for people who will do the daily five minutes.
Start With One Bed
Set up one bed, run it for a couple of months, and see whether the routine fits your day and whether your animals take it. Expanding to multiple beds before establishing that is how most azolla units end up as empty lined pits.
Feeding proportions and management practices vary by livestock type and region. Consult your veterinary officer or Krishi Vigyan Kendra before making significant changes to your animals’ ration.
