Bio-fertilizers

RESOURCE MATERIAL ON BIO – FERTILISERS

 

Rural Development Organisation.

173, P.K. Street,

Tirupati – 517 501.

Chittoor Dist., A.P.

 

v           Nitrogen (N), Phosphorus (P) and Potassium (K) are the most important among 17 plant nutrients

v           Plant can not absorb the gaseous nitrogen available 78% in atmospheric air

v           The plant absorbs nitrogen only in the form of solid

v           Conservation of gaseous form of nitrogen into solid form is called nitrogen fixation

v           Fixation of nitrogen in chemical fertilizers in factories is called  artificial nitrogen fixation (artificial fertilizers)

v           In nature there are certain micro organisms and minute plants, which can absorb gaseous nitrogen directly from atmosphere and make it available to plant in solid form. It is called natural nitrogen fixation (natural fertilizers)

v           Materials containing such organisms are called bio-fertilizers or natural fertilizers

v           They are multiplied and introduced into root zone of crop plant to supply nitrogen and phosphorus

v           Bio-fertilizers are two types 1. Nitrogen supplying bio-fertilizers and 2. phosphorus supplying bio-fertilizers

v           Nitrogen supplying bio-fertilizers are Rhizobium, Actinorhize, Aotobactor, Azospirillum, Azolla, Blue green Algae

v           Phosphorus solublizing  bio-fertilizers : phosphor-bacteria and mycorrhiza

         Nitrogen fixing bio-fertilizers

v           Rhizobium is used for pulses crops (leguminous plants)  it is available in packets and seed is treated with rhizobium before sowing

v           Actinorhize not available in the market, it was developed for leguminous plants

v           Azotobactor can be used for other than leguminous (onion, brinjal, cabbage, tomato, maize and potato)

v           Azospirilum is a non-symbiotic bacteria that can fix nitrogen independently in the soil particularly suites to grass family crops such as maize, jawar, bajra, ragi, and sugar cane

v           Azolla is used in rice crops as green manure form and dual crop form

v           Blue green Algae is suitable for rice crop and also to the other crops

        AZOLLA

        Azolla is a small aquatic fern with a branched stem and bilobed leave

v           When it dies and decays in the soil, nitrogen becomes available to plant

         Azolla can double its body weight in 3 – 5 days

v                  In 3 – 4 weeks, 5 – 10 tones of biomass can be obtained from one hectare providing at least 30 kg. nitrogen

v                 It contains 45% (N), 2.6% (P) and 0.9 % (K)

v                 It is a secondary source of nutrients such as calcium, magnesium and sulphaur

v                 The use of Azolla is rice filed at the rate of 200 gms. per square meter area can increase rice yield by 12 – 38%

v                 Application of 10 tones of fresh Azolla biomass in one hectare, add as much as 100 kg. nitrogen

v                 Azolla grows well in soils with less clay and more sand with an optimum PH ranging between 5 – 7 and temperature range of 20 – 30⁰ C

v                 Azolla can be dried and preserved for later use as manure

v                 300 kgs. dry azolla is equivalent to 5 tones of green azolla

           Production of Azolla culture

v                 Azolla can be multiplied easily even by an ordinary farmers. There are two methods of Azolla multiplication i. standing water method and ii. Nursery method

            Standing water method

v           A pond or a field with shallow standing water is chosen

v           The depth of water is 5 – 10 cm. for Azolla cultivation

v           4.8 kgs. super phostphate is applied for rapid growth

v           Introduce fresh and pure Azolla in the standing water

v           In 3 weeks the Azolla multiplies to form a carpet on the water surfce

v           It can be collected and used immediately or dried and preserved for later use

v           The process is repeated to produce more Azolla culture

        Nursery method

v           Azolla is raised in small nursery plots of 50 – 100 square meter size with strong bunds

v           Permanent Azolla nurseries can be constructed with brick and cement to avoid percolation and polythene sheets

v           300 – 400 gms. of fresh Azolla is inculcated in the tanks

v           It produce 8 – 10 tones of bio-mass in 20 days

        Methods of application

v                 azolla can be applied in two ways : Green manure form and dual crop form

v                 Azolla is usually applied in rice fields in both ways

v                 Application of green Azolla form produces better results than dry form

           Green Manure of Azolla

v            The Azolla bio-mass grown in the nursery or grown in the same field is incorporated before transplanting rice seedlings by pudding

v           The Azolla decomposed rapidly within 7 – 10 days

v           34% of nitrogen is available in 2 weeks after incorporation, 63% after 4 weeks, 76% after 6 weeks and 85% after 8 weeks

      Dual cropping with rice

v           Azolla is grown along with rice crop

v           One week after the planting of rice seedling fresh Azolla at the rate of 200 – 300 gms. per square meter should be applied in the standing crops

v           Azolla bio-mass is formed in three weeks

v           Water is drained out and Azolla will decay in the soil

        Preservation of inoculation

v           The Azolla is preserved in slow moving water bodies such as streams, canals, sewages, channels, small ponds, tanks and unused wells. The optimum temperature is 15 – 35⁰ C

BLUE GREEN ALGAE

v           Blue Green Algae mostly grows in wet places. Hot and moist weather regions are congenial for algae growth.

v           Blue green algae, besides fixing nitrogen, carry out photosynthesis and secrete certain growth hormones (Vitamin B12, auxins and ascorboic acid) which are beneficial to rice plants.

v           The use of blue green algae is confined only to rice crop. Various experiments have proved that the use of algae increases the rice yield by 10-15%.

v           It is estimated that in general blue green algae supply about 30-40 kg of nitrogen per hectare to paddy crop.

v           Blue green algae have also shown its effectiveness in improving in improving saline and alkaline soils.

       a. Multiplication of algae

v           One hectare of paddy crop requires 10-15 kg or 50-75 packets (200 gms each) of blue green algae culture.

v           Therefore, it is advisable to purchase one packet and use it to multiply the culture at home.

  The following procedure can be adopted for multiplication of blue green algae :

i.                    dig a pit of 1.83 m length, 0.92 width and 25 cm depth (6” x 3’ x 10”) on a leveled but slightly elevated and sunny site protected from animals and children;

ii.                 the sides are made sloppy towards the pit bed;

iii.               the bottom of the pit is leveled well and the sides made straight and smooth;

iv.               spread a polythene sheet in the pit stretching the edges 2-3 inches beyond the boundary where it should be fixed with stones or soil to keep it in position.

v.                  About 10 kg of soil free from stones, pebbles and roots (preferably sieved soils) is spread over the polythene sheet. This soil should be neither acidic nor alkaline.

vi.               about 200 gms of super phosphate is also spread over the soil;

vii.             the pit is gently filled with water up to a height of 10 cm above the soil level.

 

viii.          if available, 2-10 gm sodium ammonium molybdate and 1-2 drops of malathion insecticide is applied to ensure better growth and protection of algae culture;

ix.               the contents of the pit is stirred gently using a wooden stick with round and smooth edges to avoid tearing of the polythene sheet;

x.                  the soil is allowed to settle down at the bottom of the pit.

xi.               Saw dust is spread over the water uniformly as it would provide some sort of an anchorage for the geminating algal spores;

xii.             Sprinkle blue green algae culture uniformly over the water;

xiii.          The pit is protected against domestic animals, frogs and children and the water level has to be maintained at the optimum height (10 cm);

xiv.           after 4-5 days algal growth is noticed, and it covers the entire water surface in 15-18 days and forms a thick layer.

xv.             when algal growth is completed, water is drained out to allow the algal layer to dry;

xvi.           the dry algal layer sticking to the pit bed soil is scratched out along with a soil layer avoiding any damage to the polythene sheet;

xvii.        the soil in the pit is changed after three harvests; and

xviii.      repeat the procedure till sufficient quantity of algal culture is produced.

About 1.5 to 2 kg algal culture can be harvested in one harvesting from on pit. After drying in the sun, powder the culture and store in polythene bags in cool and dry place for 2-3 years. Blue green algae should be multiplied in summer as it does not thrive well in cold season.

b. Precautions

i.                    the pit should be protected against animals, children, frogs and other predators;

ii.                 the polythene sheet should be intact;

iii.               avoid shading over the pits;

iv.               avoid flooding of the pit at raining; and

v.                  avoid winter months for multiplication

      c. Application in rice fields

Apply algal culture in the rice field at the rate of 10-15 kg per hectare. It should be applied in standing water just after transplanting and do not allow the culture to flow out of the field. Water level in the field is maintained always around 8-10 cm height. Generally algae grows fully and covers the whole field within 15-20 days time. After draining out the water algae may be incorporated into the soil through various intercultural operations. This practice will enhance repeated multiplication of the algae.

Phosphorus solublising bio-fertilizer

v           Phosphobacteria is sold in polythene pockets, this bacteria can convert unavailable form of phosphorus into available form by solublizing

v           Mycrohiz is not technically feasible and economically valuable

Advantages of bio-fertilizers

v     Cheap source of nutrients

Biofertilizers can be called as poor mans technology. Taking into account the amount of nutrient supplied,biofertilisers are many times cheaper than chemical fertilizers.25Kgs nitrogen chemical fertilizers costs Rs,360/- per hectare  whereas the BGA costs Rs,60/- per hectare to produce 10Kgs BGA culture.

v     Suppliers of micro nutrients

Biofertilizers not only supply nitrogen and phosphorous but also some micronutrients essential for plant growth. Sometimes yield is limited by micronutrients and application of nitrogenous,phosphatic and potassic fertilizers does not improve yield significantly. In this situation the application of bulky biofetilizers like blue green algae and azolla increases yield due to greater supply of micronutrients.

v     Supplier of organic matter

Organic matter is the essential component of the soil. It serves as an inexhaustible source of nutrients and energy for plant as well as for useful micro-organisms. Organic matter has great impact on the physical and chemical properties of the soil.Azolla and BGA produce an average 8-10 tone of biomass per hectare which adds to the organic matter pool of soil

v     Counteracting negative impact of chemical fertilizers

When chemical fertilizers are excessively and continuously used for a few years, they may create acidity or alkalinity in the soil and deteriorate the quality of soil. Soil also becomes unresponsive to further use of similar fertilizers. Application of biofertilizers can avoid this problem to a great extent. Besides, large amount of organic matter supplied by the biofertilizers impart tolerance power (buffering capacity) to the soil against acidity or alkalinity. It also withholds metallic elements from entering the plant roots, thereby reducing harmful effects of pesticide.

     

v     Secretion of growth hormones:

 

      Plants also need for their growth and development; some natural complex chemical compounds called hormones. Though growing plants do not themselves synthesize hormones in adequate amounts, azotobactor blue green algae and azolla have been found to synthesize growth hormones ( eg indelicate acid and vitamin B)which benefit the main crop.Sometimes,biofertilizers applicationgives significany response even if the soil is already rich in plant nutrients.This occurs due to the supply of growth hormones by biofertilizers to the main crop.