azolla and its role in crop production
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Azolla Azolla and Its Role in Crop Productionand Its Role in Crop Production
Jayanta Chabukdhara (2007-AB-06) & Jonali Sarma (2005-AJ-46)3rd Year 1st Semester, B.Sc (Agri)B.N. College of AgricultureAssam Agricultural University2009
TopicTopicSeminar on Soil 313 (Optional)Seminar on Soil 313 (Optional)
Introduction: Azolla is a Potential Bio-fertilizer
• Azolla a dichotomously branched free floating aquatic fern is naturally available mostly on moist soils, ponds and is widely distributed in tropical belt of India.
• Morphologically Azolla species is typically triangular measuring about 1.5 to 3.0 cm in length 1 to 2 cm in breadth.
• Azolla remained suspended in water and Roots emanating from growing branches which is one of the potent nitrogen fixing species which are extensively used in modern Agriculture as Biofertilizer
Introduction: Azolla is a Potential Bio-fertilizer
The dorsal lobe of Azolla remains exposed to air is having a specific cavity containing its symbiotic partner, a Blue Green Algae (BGA), the Anabaena azolae.
The fern is capable of fixing atmospheric nitrogen in the soil in the form of NH4
+ and becomes available as a soluble nitrogen for the wet land rice crop, which is the major cereal for the people of the northeastern India
What are we going to talk about?
Biological nitrogen fixation accounts for most of the fixation of atmospheric
N2 into ammonium, thus representing the key entry point of molecular nitrogen
into the biogeochemical cycle of nitrogen
In this seminar we will plan to discuss the role of symbiotic relations between
nitrogen-fixing Pteriodophytes and Cyanophycean algae for improvement of
crop production i.e Biological nitrogen fixation
Classification -Taxonomy of Azolla and Biochemical Profile
Classification (Taxonomy)
Class : Pteridophyta
Order : Salvinales
Family : Azollaceae/Salvinaceae
Genus : Azolla
Sub Genus : Eu-Azolla
The International Rice Research Institute Azolla germplasm
Collection
species Code number
A. pinnata var. imbricata
PI001
A. filiculoides FI1001
A. mexicana ME2001
A. caroliniana CA3001
A. microphylla MI4001
A. nilotica NI5001
A. pinnata var. pinnata PP7001
Unknown 8001
Classification -Taxonomy of Azolla and Biochemical Profile
On dry weight basis the chemical compositions of Azolla are• Nitrogen 5.0 % • Phosphorous 0.5 % • Potassium 2.0-4.5 % • Calcium 0.1-1.0 % • Magnesium 0.65 % • Manganese 0.16 % • Iron 0.26 % • Crude Fat 3.0-3.3 % • Sugar 3.4-3.5 % • Starch 6.5 % • Chlorophyll 0.34-0.55 % • Ash 10.0 %
How to grow Azolla?• In low land, field is ploughed, leveled and small
bunds of 50 cm width are made to make small ponds of 3 x 2 x 1 m size.
• Only 10-15 cm standing water is allowed in the ponds.
• The green Azolla @ 50 -200 g/ sqm + P through SSP @ 20 kg/ha along with Furadan 1 g/kg of Azolla is mixed and released in the pond maintaining a 10-15 cm of water level, for further growth and multiplication of Azolla.
How to grow Azolla?• Azolla multiplies rapidly and form a green mat like a carpet on
water surface of ponds in just two weeks. This green Azolla is harvested in bamboo basket and transferred and released in the transplanted rice field for further multiplication, as dual cropping with rice for fixing nitrogen to rice crop.
• Harvested green Azolla could be converted in to compost by pounding in pits for a month which is then used like FYM for other crops grown under upland situation.
• During summer, green Azolla is harvested at an interval of 15-
20 days but during winter growth of Azolla becomes slow due to moisture stress and low winter temperature, hence Azolla can be harvested at 25-30 days interval during winter.
Homestead methods of Azolla cultivation
Azolla is a free floating water fern which lives in symbiotic assotiation with a N- fixing blue- green algae (Anabaena azollae) & has potential of providing 30-60 kg N/hac under normal field condition.
Azolla contains 4-6% N, 0.69% P2O5, 4% K2O , 0.75% Ca & 0.50% Mg. It offers resistance against pest & disease. During lean period the fresh biomass can be converted into nutrient rich compost.
Methods of Azolla caroliniana cultivation
A low cost rapid multiplication methods of A caroliniana developed in soil. Micro biology & bio fertilizer lab of AAU Jorhat has been detailed as:
1. Dig out a pit in the ground of size 2m X 1m X 0.20m & level
2. Place good quality polythene to cover the pit.
3. Raise bund through mud plastering all around the pit.
4. Maintain water level at 10-20 cm.
5. At 10gm each of SSP , MOP & Zn Sulphate plus 200gm of dried powdered cowdung.
6. Apply 300 -400 gm of Azolla in the pit.
7. Multiply azolla for 15-20 days until a thick azolla mat is formed & by this time there will be increase in fresh biomass to the tune of 8-10 times.
8. For continous harvest of fresh azolla ,10-15 nos of the above sized pits are required.
Mechanism of atmospheric nitrogen fixation and favourable condition for growth and developments
• The remarkable feature of Azolla is that its symbiotic relationship with Cyanobacterium (Anabaena azollae) which remained on the dorsal leaf cavity of Azolla. The fern provides protein substances to Anabaena (BGA). The BGA then absorbed the atmospheric nitrogen and decomposes it through enzymic activity and converted in to soluble ammonia (NH+).
• Water: 10-15 cm fresh current water is necessary in multiplication pond.
• Temperature: The day/night temperatures ranging between
32ºC and 20ºC have found to be most favourable. The optimum temperature for luxurious growth of Azolla is 25-30ºC and can be raised successfully in the mid hills.
Contribution of Azolla in improvement of Crop Production
• Basal application on green Azolla manure @ 10-12 t/ha increases soil nitrogen by 50-60 kg/ha and reduces 30-35 kg of nitrogenous fertilizer requirement of rice crop.
• Release of green Azolla twice as dual cropping in rice crop @ 500 kg/ha enriches soil nitrogen by 50 kg/ha and reduces N requirement by 20-30 kg/ha.
• Use of Azolla increases rice yield by 20 to 30 %.
• Rice varieties like DR-92, RCPL-1-87-8, Mendri, H.-2850 and Manipuri produced more than 30 q/ha rice yield when grown with Azolla as dual cropping under natural soil fertility.
Contribution of Azolla in improvement of Crop Production
• Under low land condition a thick Azolla mat does not allow the weeds to grow in rice filed thus, Azolla suppresses the weed growth and creates congenial condition for rice production.
• Azolla reduces evaporation from water surface and increases water use efficiency in rice.
• Dry Azolla flakes can be used as poultry feed and green Azolla is also a good feed for fishes.
Contribution of Azolla in improvement of Crop Production• Azolla is a water fern which is used as a biofertilizer for rice
and has been found effective. Blue green algae, Anabaena azolla lives in the dorsal cavity of azollae and fix'N'. It is also able to reduce the 'N' bill to the extent of 25 to 30 kg / ha. It is raised as a dual crop and also applied as green manure .
• The Azolla–Anabaena association can fix as much as 0.5 kg of atmospheric nitrogen per hectare per day, a rate of fertilization that is sufficient to attain moderate rice yields.
New Horizon of Azolla Use- Biofertilizer For Rice
• AQUATIC fern Azolla is a promising nitrogen –Fixing biofertilizer for rice.
• Azolla adds adequate organic matters and improve soil fertility
and soil health.• Azolla Checks weed growth, enhance efficiency of applied
chemical N-fertilizer and reduced environmental pollution• Azolla can be easily grown in lowland condition, with an annual
biomass production of more than 300t/ha.• Azolla can be used successfully both during wet and dry seasons• Azolla is well suited for irrigated and rain fed favourable shallow
lowlands (0-25 cm water depth)• About 5 to 10 cm standing water, slightly acidic to natural soil
(pH 5.5-7) with high available P, moderate temperature (25-300 and reasonably high light intensity are congenial for its growth.
New Horizon of Azolla Use- Biofertilizer For Rice
• One crop of Azolla produce 10 to 20 t of fresh biomass and suplies 20 to 40 kg N/ha. It results in a saving of about 30 kgN/ha and is suitable for rice verities of all duration.
• Most of the native strains of Azolla mate are susceptible to insect pests.
• The Central Rice Research Institute, has identified a strain of Azolla caroliniana with tolerence to major insect pests. This strain is now recommended for large scale use, and also has better growth and nitrogen fixing ability than Azolla pinnata
Inoculum Production
• Azolla is presently produced to vegetative propagation which is simple, efficient and can be easily adopted by the farmers.
• Divide the well prepared field into 10 to 25 m2 plots by raising bunds.
• Maintain 5 to 10 cm standing water throughout.• Inoculate fresh Azolla @100 to 200 gm/m2.• Apply single super phosphate (SSP) @ 2.5 to 3.75 gm/m2
every week.• After mate formation harvest 2/3 of Azolla leave the remaining
1/3 for further multiplication.• A 100 m2 nursery yields 1000 to 1500 kg of fresh inoculum
every week.
UtilizationGreen manuring
• Grow Azolla 15 to 20 days before transplanting of rice by applying 1 to 2 tone fresh inoculum/ha in a well prepared field.
• Apply SSP @ 62.5 kg/ha in tree equal splits at an interval of 7 days. If needed apply Furadon @ 3 kg/ha to control insect pests of Azolla.
• After formation of thick mat, drain out water and plough the field for incorporating Azolla into the soil.
• Transplants rice seedling after 1 to 2 days. • Azolla green manuring produces 1 to 2 t/ha extra rice yield.• It is also used in decoration of drawing room.
Important Consideration
• Phosphorus for Azolla should be used from that recommended for rice
• Fresh animal dung@1 to 1.5 t/ha or cattle slurry @ 2-3 kl/ha can also used in place of P fertilizer
• Application of N fertilizer as basal dose in case of dual cropping and top dressing in case of green manuring is needed
• Azolla inoculation should be avoided for two to three weeks after the application of pre-emergence herbicides such as Butachlor and Benthocarb, as these substantially reduced growth and multiplication of Azolla.
Other Uses• Azolla contains 16% protein on dry weight basis and can be used as
supplemented feed for animal such as fish, ducks, poultry birds, pigs and cattle
• Azolla is an efficient Scavengers of potassium and benefits the rice crop in K- deficient soils.
• Azolla helps in detoxification of heavy metals and many other pollutants.
• Azolla compost can be applied for cultivation of fruits and vegetables
• Azolla can be used for the production of biogas.
Different Azolla spp. Found in Assam
• Pistia stratiotes (Borpuni)
• Lamna paucicostata (Sorupuni)
Literature Cited• Shing D P (2002).Azolla Biofertilizer for
Rice.CRRI Technology Bulletin 12,CRRI,ICAR, Cuttack
• Lincoln Taiz and Eduardo Zeiger (2006).Plant Physiology 3rd edition, Springer
• Journal of the North Eastern Council, Shillong
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