Effects of Azolla on rice and other crops
Azolla was used for green manuring for rice in different ways to studies its effect on rice field. Azolla decomposes very fast releasing 75 percent of its nutrients for standing crop rice. Positive response on rice yield has been observed at different locations.
Benefits of Azolla
- It contains: N 3-6%, P2O5 1-2%, K2O 4.5%, Ca 1%, Mg 0.6%, Mn 0.16% Fe 0.26%. The N accumulated in the Azolla biomass is made available to rice crop after decomposition.
- Increase the content of organic matter, N, P, and K in Azolla applied soils. Increased availability of micronutrients as a result of Azolla incorporation.
- Azolla improves the physical properties of soil (Bulk density, aggregates, stability and available moisture content) so improves the soil fertility.
- It prevents weed growth in rice field water.
- Fixation of 30 – 100 kg N/ha Yield increases 20– 25 %
- Besides, it is used as green manure and for aquaculture
- 10 tones fresh Azolla/ha is equivalent to 25-30 kg N/ha.
- Adds growth-promoting substances, improve the soil’s aeration and water holding capacity.
Problem on Azolla utilization
✓ Periodic incorporation of azolla is essential otherwise thick biomass of azolla may harm to grow rice during tillering stage.
✓ Weevil, moth, nymphula, pyralid and common aquatic snail are some of the destructive pests of azolla
which destroy within no time by rolling leaves and eating leaves.
✓ Damping off diseases of azolla is commonly caused by decomposition of lower portion of azolla if thick biomass left incorporated.
✓ Good management of irrigation water is needed.
✓ Periodic draining of water sometimes essential for setting the azolla biomass for incorporation.
✓ Azolla sometime gets washed away with heavy rain without providing much benefit to crops.