Azolla as cattle feed

Dear Subhra Shaikat,

I think the following points will help you to start Azolla Cultivation

Anoop

1. Which kind of P fertilizer is used for azolla cultivation

Azolla is very responsive to phosphorus and requires a continuous supply for rapid growth. Trials have shown that each kilogramme of phosphorus resulted in more than 5kg of additional nitrogen in the Azolla biomass after 35 days' growth.

The soil should have at least 30 ppm phosphorous. If soil test indicates a lower level, apply 5Kg/ha mono-ammonium phosphate (16-20-0) or super phosphate (0-18-0) at kg/ha/wk or when the growth of azolla is below normal because of insufficient phosphorous. Approximately 4 Gms of 2 M2 of the tank

After one month, of continuous harvest from the tank, some amount of cow dung slurry will be needed to top up, when P fertilizer is to be applied, about 1 Kg per 2 M2 in diluted form. After two months, or when growth is retarded, the soil and the bottom need to be scooped out partially, and top up with fresh soil. As continuous cultivation will deplete some of the important micro nutrients.

Pressmud from Sugarcane factory or tank silt or other locally available substitutes can be used for enhancing the availability of phosphorous for optimum growth. This can be incorporated into the soil layer.

Given above is standard followed for an hectare, thus divide the area by hectare and reduce proportion of the application accordingly.

2 Some idea of shelf life and post harvest handling

After the tank is seeded with azolla, it takes sometime to stabilize the production. Once stabilized, the doubling time of azolla is 7 days.

Azolla is normally used fresh for seeding the paddy fields, either before transplanting or after transplanting which assist in availing “N” to the growing plant, other wise it used for feeding livestock. It is best used for livestock as fresh material, as it is rich source of protein, mineral and vitamin particularly Vitamin A.

It can also be used for feeding the worms in vermin composting.

3. Azolla thriving in summer months

Optimum temperature for azolla is 25°C or less. Temperatures above 30°C can cause slow growth rate and infestation of insect problems. Partially shade the Azolla culture by growing Sesbania around the multiplication pond. Growing a trellised crop(vines which yield fruits) over the pond will also help. Use shade net over the tank for lowering the direct heat from the sunlight in summer, 50% shade net made for the nursery, can reduce the temperature by 5 to 7 OC. Besides it will reduce the evaporation rates, and maintain the relative humidity higher the surrounding areas. For this, the shades can be used for covering the sides as it will reduce the direct action of the wind.

The other option, with care is to reduce the water level in the multiplication tank. Allow the Azolla to grow on saturated mud which is cooler than the standing water , care must be taken that the level of water is maintained and not allow the soil to dry out.

4. Disease infection to azolla grown in a tank

Commonly disease are rare or uncommon, due to intensification, disease might come prevalent. Protect the sides against the wind, as the winds will cause the azolla to pileup, which create ideal conditions for insects to multiply. With proper sanitation and disinfections the incidence of disease can be curtailed.

5. Harvest index of azolla

Azolla is a small aquatic fern (usually 1-5 cm large) which can also grow on saturated or moist soils or on thin layer of water. Azolla can grow exponentially. It is capable of doubling its weight in 5-7 days.

Growth Status   Period     Status/inference1 Fast      4 to 6 days     Good
2 Moderate 7 to 9 days      Observe, prepare for taking status
3 Slow      more than 9 days      Take stock of the nutrient and environmental status , prepare of action

Environmental Factors Affecting Growth of Azolla (In Nutshell).

Sl No   FACTORS   RANGE
1   Temperature       20°C - 28°C
2   Light       50% full sunlight
3   Relative Humidity     65 - 80%
4   Water (standing in the tank)     5 - 12 cm
5    pH      4-7.5
6   Salinity      90 -1 50 mg/litres

Troubleshooting common problems in azolla production

1. Slow growth

Slow growth of Azolla is usually due to phosphorous deficiency, insect attack/ damage, high temperature, intense sunlight.

a. Phosphorous deficiency

Apply 5 kg/ha mono-ammonium phosphate (16-20-0) or superphosphate (0-18-0) weekly per hectare. Press mud or other locally available substitutes can be used.

b. Insect attack/damage -- Symptoms are the presence of moths or beetle. Other symptoms include a purplish or brownish color (caused by Azolla snout beetle); silken threads (Azolla moth);

• Do not allow the Azolla to overlayer or pileup as this increases the chances of insect infestation and damage.

c. High temperature/intense sunlight -- A brick red color of the Azolla indicates high light intensity. Too much heat will cause the Azolla to turn brown/reddish pink. The loss of the plant's green pigment (chlorophyll ) will retard photosynthesis, consequently causing slow growth and lowering multiplication.