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Azolla
and Its Role in Crop Production
Topic Seminar on Soil 313 (Optional)
Jayanta
Chabukdhara (2007-AB-06) & Jonali Sarma (2005-AJ-46) 3rd Year Year 1st 1s t Semester, B.Sc (Agri) B.N. College of Agriculture Assam Agricultural University 2009
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Introduction: Azolla is a Potential Biofertilizer a dichotomously branched free floating aquatic fern is naturally available mostly on moist soils, ponds and is wide delly di disstribu butted in trop opiical belt of Ind ndiia.
Azolla
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 us ed in mod oder ern n Ag Agri ricu cult ltur uree as Bi Biof ofer erti tili lize zer r
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
Classification
(Taxonomy)
Class
:
Pteridophyta
Order
:
Family vinaceae
and Biochemical Profile The International Rice Research Institute Azolla germplasm Collection species
Code
number
Salvinales
A. pinnata var. imbricata
PI001
:
Azollaceae/Sal
A. filiculoides
FI1001
Genus
:
Azolla
A. mexicana
ME2001
Sub Genus
:
Eu-Azolla
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 5.0 % Nitrogen 0.5 % Phosphorous 2.0-4.5 % Potassium 0.1-1.0 % Calcium 0.65 % Magnesium 0.16 % Manganese 0.26 % Iron 3.0-3.3 % Crude Fat 3.4-3.5 % Sugar 6.5 % Starch 0.34-0.55 % Chlorophyll 10.0 % Ash
How
to grow Azolla?
In low land, field is ploughed, leveled and small bunds of 50 cm width are made to make small ponds of3x2x1msize.
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?
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.
Azolla
Harvested
During
green Azolla could be converted in to compost by pounding in pits for a month which is then used like FY M for other crops grown under upland situation. summer, green Azolla is harvested at an interval of 1520 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 bluegreen algae (Anabaena azollae) & has potential of providing 30-60 kg N/hac under normal field condition. Azolla contains 4-6% N, 0.69% P 2O5, 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 810 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 (N H+).
Water:
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 2530ºC and can be raised successfully in the mid hills.
10-15 cm fresh current water is necessary in multiplication pond.
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. reduces evaporation from water surface and increases water use efficiency in rice.
Azolla
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 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 .
Azolla
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.
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 (25-30 0 and reasonably high light intensity are congenial for its growth.
Azolla
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
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. Azolla
Green manuring
Utilization
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
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
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, S pringer
Journal
of the North Eastern Council, Shillong
Thank
You
