Blue green algae (Part C)

Algal Production Technology

The success of any technology usually depends upon its techno-economic feasibility. The algal production technology developed and reported by different Algologists is very simple in operation and easy in adaptability by Indian farmers. The technology has got potential to provide an additional income from the sale of algal biofertilizer. In general, there are four methods of algal production have been reported viz, (a) trough or tank method, (b) pit method, (c) field method and (d) nursery cum algal production method. The former two methods are essentially for individual farmers and latter two are for bulk production on a commercial scale.

1. Trough method:

1. Prepare shallow trays (2mx1mx23 cm) of galvanised iron sheet or permanent tank. The size of the tank can be increased if more material is to be produced.

2. Spread 4 to 5kg of river soil and mix well with 100g of superphosphate and 2g Sodium molubdate.

3. Pour 5 to 15cm of water in the trays. This will depend upon local conditions i.e. rate of evaporation. Mix the ingredients properly.

4. In order to avoid the nuisance of mosquitoes and insects add 10 to 15g Furadon granules or malathion, or any other suitable granules.

5. The mixture of soil and water will settle within 8-10hours. At this time, add 200 to 250g mother culture of blue green algae to the surface of water. Then don’t disturb water.

6. The reaction of the soil should be neutral. If the soil is acidic then add CaCo₃ in order to bring the pH of the soil to neutral.

7. If sunlight and temperature are normal then within 10-15 days the growth of the blue green algae will look hard flakes on the surface of the water/soil. Similarly, water level will be reduced due to evaporation.

8. This way water in the tray/pit is allowed to evaporate and the growth of the algae flakes is allowed to dry.

9. If soil is dried the algal growth is separated from soil. These pieces of algal growth are collected and stored in plastic bags. In this way from one sq.m.tray or/pit about half tonnes kg blue green algal growth is obtained.

10. Again add water to trays and stair the soil well. Then allow the algae to grow in this way. This time it is not necessary to add mother culture of algae or superphosphate. In this manner one can harvest growth of algae 2-3 times. After this effect of superphosphate and soil is reduced.

1. Pit method:

This method of production of blue green algae does not differ from the one described above i.e. trough method. Instead of troughs or tanks pits are dug in the ground and layered with thick polythene sheet to hold the water or one half cement plastered tanks. Other procedure is the same as in the trough method. This method is easy and less expensive to operate by small farmers.

2. Field scale method:

The field scale production of blue green algae is really a scaled up operation of trough method to produce the material on a commercial scale. This type of method of algal production is more common amongst farmers of south India.

1. Demarcate the area in the field for algal production: - The suggested area is 40m². No special preparation is necessary although algal production is envisaged immediately after crop harvest, the stubble is to be removed and if the soil is loamy it should be well puddled to facilitate water logging conditions.
2. Prepare a bund with earth so as to store the water.
3. Flood the area with water to a depth of 2.5cm. In trough or pit methods flooding is done only in the beginning, while in field scale method flooding is repeatedly needed to keep the water standing.
4. Then apply superphosphate 12kg/40m².
5. To control the insect-pests attach, apply carbofuran (3% granules) or Furadon 250g 40m².
6. If the field has received previously algal application for at least two consecutive cropping seasons no fresh algal application is required. Otherwise apply the composite algal culture of 5kg/40m².
7. In clayey soils, good growth of algae takes place in about two weeks in clear, sunny weather, while in loamy soils it takes three to four weeks.
8. Once the algae have grown and formed floating mats they are allowed to dry in the sun in the field and the dried algal flake, are then collected in sunny bags for further use.
9. One can continually harvest algal growth from the same area by reflooding the plot and applying super phosphate and pesticides. In such situations an addition of algal innoculum for subsequent production is not necessary.
10. During summer months (April-June), the average yield of algae per harvest ranges from 16-30kg/40m².

1. Nursery cum algal production:

Farmers can produce algae alongwith seedlings in their nurseries. If 320m² of land are allotted to prepare a nursery, an additional 40m² alongside can be prepared for algal production as described above. By the time rice seedlings are ready for transplantation about 15-20kg of algal material will be available. This much quantity of algal mass will be sufficient to inoculate one and half hectares of area. If every farmer produces the algal material required to inoculate his own land then he will reduce the cost of algal innoculum required to be purchased. So also one can cut the cost of chemical fertilizers to be applied as recommended.

Recommendation of algal biomas for field application:

1. If mineral nitrogen fertilizers are not used, apply blue green algae biofertilizer in order to gain the benefits of 30-40kg Nitrogen/ha.

2. Broadcast the dry algal material over the standing water in the rice field at a rate of 10-15kg/ha one week after transplanting the seedlings.

3. Addition of excess algal material is not harmful and will accelerate the multiplication and establishment in the field.

4. The sun dried algal material can be stored for a long time in a dry state without any loss in viability.

5. Do not store the algal material in direct contact with chemical fertilizers or other chemicals.

6. Apply algae for atleast three consecutive seasons so that there will be sufficient algal innoculum found in the field.

7. Recommended pest control measures and other management practices don’t interfere with the establishment and activity of algae in the field.