How To Grow Azolla

When training farmers on how to grow azolla in Kenya using Grekkon Limited’s dam liners, and shade nets, the company offers a detailed session to farmers as documented in this article. Azolla pinnata is the most common variety grown in Kenya

What is Azolla?

Azolla, belonging to the Salvinaceae family is a fresh water aquatic plant. It is a nitrogen fixing, branched free-floating fern also referred to as duckweed, mosquito fern or water fern. Its most popular characteristic is its ability to exponentially grow by doubling its biomass every 3 days depending on the growing conditions. This is why it is regarded as a super plant. Some refer to it as the green gold mine due to its high nutritive value

Azolla growing in troughs made of dam liner material, and under a green shade net – materials supplied by Grekkon Limited

Benefits of azolla

• it is a green manure because of its nitrogen fixing property
• it reduces weeds
• soil organic carbon is increased which in turn microbial biomass in the soil
• as a livestock feed, its is an economical way of providing affrodable high protein, essential amino acids, and vitamins (A, B12, Beta Carotene) to animals

How to grow azolla in Kenya

Nutrition Requirements

i .Light: Azolla grows well under partial shade. Growth decreases quickly under heavy shade (lower than 1,500 lux) and more than 50% of full sunlight reduces photosynthesis. This is why a shade net cover is necessary where sunlight is intense. It causes it to turn reddish brown, which reduces the nutrient value

ii. Nutrition: for vigorous production, add 20kgs per Ha of phosphorous. Cow dung slurry, and super phospahte fertiliser provides this

iii. Relative humidity : high at 80 – 90 %

iv. Growing PH: lightly acidic media at : 5.2-5.8

v. Temperature: keep it below  25 degrees centigrade for a luxurious growth. Where it exceeds this, provide a shade net cover

vi. Water: fresh water 10-15 cm in the multiplication pond, adequate water level in the pond is 4 inches

Steps on how to grow azolla

• select a pond site in a cool shaded location. Shade minimises evaporation, and encourages rapid growth. Ensure that that the pond site is close to a water source. To produce 1kg of azolla daily, the pond will be 2M (L) x 1.5M (W) x 0.15M (D) in dimension
• line the pond using a dam liner to prevent water loss through seepage into the soil
• add soil mixed with cow dung in the pond. Slurry can also be used. These are mixed with water and spread uniformly in the pond
• add 1kg of azolla culture

A simple azolla growing trough

How to grow azolla

Maintainance

• add 20g of super phosphate mixed with 1kg cow dung every 5 days to keep it’s growth vigorous
• replace the azolla crop after 6 months
• harvest the crop after 15 days by hand or a plastic scoop, then every 3 days afterwards to avoid overcrowding, and maintaining a large biomass. With good feeding, the yield is 1.5kgs – 1.6kgs every 3 days
• clean it thoroughly to remove the cow dung smell
• dry it or feed it fresh to livestock. It can also be mixed with other animal feeds

Azolla harvesting by hand

Harvested azolla in plastic containers

How to Grow Azolla

FAQs

1. How profitable is azolla farming in Kenya?

Azolla farming is profitable beacuse of its many uses. It can be grown commercially as;

• livstock feed
• a bio fertiliser
• as propagation material to sell to other farmers seeking to set up azolla growing units

2. What is azolla used for?

As a nitrogenous fertliser, and as an animal feed. It is easily digestible because of its high protein and low lignin content. It increases feed efficiency, daily anaimal weight gain, and milk production by 15% – 20%

3. Why is my azolla turning black?

It first turns brown due to too much exposure to sunlight, high temperatures, lack of nutrients in the pond or fungal / bacterial diseases. Eventually, the crop dies

4. Can azolla survive without sunlight?

No. This is important to note when fixing a shade net over it

5. What are the negative effects of azolla?

Azolla shades out other water plants, killing them together with fish and other aquatic animals. Its decay creates a strong odour which affects fish and other aquatic animals

6. What are the limitations of azolla?

It cannot grow in a waterless environment

7. Does azolla repel mosquitoes?

Yes it does by over 95%

8. Does azolla increase eggs production in chicken?

Yes it does because it provides protein, that adds weight to the bird

An azolla crop turning brown

Dam Liners Prices in Kenya

Dam liners prices in Kenya for irrigation by Grekkon Limited vary annually by raw material cost. These dam liners will be installed on reservoirs, or water tanks. Their purpose is to prevent water loss through absorption by the soil surface.

Our dam liner material is high density UV treated geomembrane. UV treatment is to slow down degradation by the sun during external use. Grekkon Limited’s dam liners for sale in Kenya are categorised according to thickness

A small water reservoir for vegetable irrigation with a 0.5mm dam liner installed by Grekkon Limited in Emabungo area, Vihiga county. Notice the fence around it fo safety reasons

Dam Liner Prices in Kenya

Introducing the 1.5mm dam liner for Kes 780/M square all inclusive

Notes

• Welding cost applies when the liner required is wider than 8M
• Installation cost is charged when a Grekkon Limited technician installs the liner

Dam Liners Material Thickness Application

1. 0.5mm liners are for smooth surfaces without stones or rocks. It will work on a surface with murram. The life span is 8 to 12 years
2. 0.75mm liners are for rough surfaces with some stones or rocks. The lifespan is 15 to 20 years
3. 1mm liners are for stony or rocky surfaces. The lifespan is over 25 years

The choice of liner thickness is a factor of the liner size. A liner holding 10,000 cubic is thicker than one holding 500 cubic

Dam Liners Prices In Kenya

Processes Every Grower Should Know

I. How to calculate your dam liner size

• Measure your reservoir length (L), width (W) and depth (D) in meters
• Apply the formula; (L+2D+2) + (W+2D+2). This converts your 3D measurement to 2D

II. Steps to install your dam liner

• Clean up your reservoir floor to remove any debris that will perforate the liner
• Lay your liner at the center on the floor of the reservoir
• Spread it out to cover the entire floor, and the walls
• Make a trench 1M away from the edge of the reservoir, all around it
• The trench measure 30cm/ 1ft deep by 30cm/ 1ft wide
• Tuck your liner in this trench, then cover it with lots of soil

III. How To Weld Dam Liners

1. Factory welding. Depending on the dam liner size, weld it whole or partially in the factory. The weight and volume of the welded material must be easily portable on site.  The latter factor guides on how much of the dam liner material will be put together in the factory
2. Site  or field welding. This is done on site at the point of dam liner installation. It is the joining together of the partially welded dam liner pieces from the factory. Site welding is done when the entire dam liner could not be wholly put together in the factory. This is as a result of weight or bulkiness, which limits lifting and transportation of the bulky and heavy material. The weight size of the portable material depends on the thickness of the dam liner. The thicker it is, the less it is
3. A wedge welding machine or a heat gun/ heat blower is the equipment that does dam liner welding. A wedge machine is what does it in the factory. The heat gun is highly portable, and so is best for field joinery

Dam liner welding involves melting the liner material under high temperature at the point of joining them. Once melted, the 2 layers are laid one over the other and as they harden, become one unit

Factory wedge welding of a 1mm  thick dam liner

Joining 2 dam liner pieces with a heat gun

IV. How to Harvest Water Using Dam Liners

Factors to consider that will affect your dam liners prices in Kenya

a. Land size

The amount of water required for half an acre is less than that needed for 20 acres. The latter will harvest more water to irrigate the greater acreage, and the former will have less water harvested. The bigger the volume of water reserved, the larger the dam liner size

b. Location

The amount of rain fall is different in every climatic zone. Growers in the cool wet highlands have just a few dry months in the year, while farmers in the dry zones have more dry months than wet. In regions where the interval between rains is long, larger reservoirs are built for the same acreage as that in the cool wet location. Again, dry locations have very high  water loss through evaporation. In this case, it is advised to set up a shade net over the water reservoir to manage this water loss

c.  Ground Elevation

The farm gradient determines the location of the water pan. Some choose to have it at the lowest part so as to capture run-off water. If it is for crop irrigation, this water is either pumped uphill to a tank from where it flows back by gravity to the crop. Or it is pumped directly to the crop from the water reservoir. Others choose to locate the water pan on the highest point of the farm so that the water, through gravity flows out to the crop. In this case, the farmer does not retain run-off  rain water from the farm. On a flat terrain, irrigation water is physically pumped out to either a high storage tank for onward gravity flow to the crop. Or directly to the crop

A low reservoir that collects run-off rain water

d. Farming System

The size of the water pan will differ for irrigation, compared with aquaculture or livestock production

e. Crop Type

Some crops are more water demanding such as leafy vegetables, than others such as herbs. Then some crops  like onion are densely spaced while others are like avocado are sparsely populated in the farm. This will determine the water requirement

f. Irrigation System

Every irrigation system has it’s own unique water use. Drip irrigation conserves water while overhead irrigation through sprinklers or rain hose kits spends huge water volumes

g. Surface Texture

The surface texture of the water pan determines the dam liner thickness to install. For a smooth surface, a 0.5mm dam liner is ok. Where the surface is stony or rocky, then the 0.75mm or 1mm dam line is better

How To Install Dam Liners In Kenya

What is dam lining?

It is the lining of the floor and walls of a water pan with a geomembrane material. This material is impermeable and holds the water above it for agricultural use

To cover a reservoir with a dam liner is a simple yet complicated task. Proper dam liner installation in Kenya will guarantee good water collection for irrigation and domestic use.  It requires proper coordination so as to achieve the intended objective. Before installation, one must learn how to measure a dam liner so as to determine the area of material needed for the water pan or tank.  Grekkon Limited is your number one company in supply and installation of dam liners in Kenya

How do you measure a dam liner?

1. Measure the length of the water reservoir
2. Measure the width of the water reservoir
3. Determine the depth from the center-most part of the water pan which is deemed as the deepest part
4. Apply this formula (length+2 depth+2 meters) X (width+2 depth+2meters). The additional 2 meters in each set are for tucking the liner. The dam liner tucking distance from the edges is taken as 1M all around te water pan

Steps on How to Install Dam liners in Kenya

Water Pan Excavation

This is the first step and usually takes the longest time. Excavation is manual with handtools, or with a machine. Most common machines for dam excavation are backhoe loaders, bull-dozers and caterpillars. At excavation, the side walls are inclined at an angle to prevent collapse of the dam.

Read Also: How to join dam liners and Quality dam liners in Kenya by Grekkon Limited

Smoothening Of The Water Pan

This is to remove any sharp objects that damage the dam liner. Pour in water on the floor and sides to soften it.

Trench Making

Trenches are dug round the dam where the dam liner will be installed. The size of the trench will depend on the size of the dam and the dam liner thickness. The most popular trench sizes are 1ft deep by 1ft wide and 1.5ft deep by 1.5ft wide.

Observe the trench made around the water pan. it is 1M from the edges of the water pan, and this is where the dam liner will be tucked

How To Install Dam Liners In Kenya

• Place the dam liner in the reservoir. This way, it takes the shape of the reservoir
• The liner must have an allowance for overlap. Bury the overlap in the trench, then cover with soil for a smooth finish. The trench dimensions will be 0.45M to 0.6M deep, and 0.3M wide. Several casual labourers make the process as smooth as possible. Where no trench has been made, support the dam liner with sand/ soil bags to achieve the same result
• Install an inlet and an over flow. The inlet is a pipe from a river, borehole or from the roof gutter section. Dams that trap run off water have a silt trap with several chambers to trap stones, mud and other debris.

How To Weld Dam Liners

1. This is done on site at the point of dam liner installation. It is the joining together of the partially welded dam liner pieces from the factory. Site welding is done when the entire dam liner could not be wholly put together in the factory. This is as a result of weight or bulkiness, which limits lifting and transportation of the bulky and heavy material. The weight size of the portable material depends on the thickness of the dam liner. The thicker it is, the less it is
2. A wedge welding machine or a heat gun/ heat blower is the equipment that does dam liner welding. A wedge machine is what does it in the factory. The heat gun is highly portable, and so is best for field joinery

Dam liner welding involves melting the liner material under high temperature at the point of joining them. Once melted, the 2 layers are laid one over the other and as they harden, become one unit. The welded joints must be leak free for the dam liner to work effectively in the tank or water pan. Lined water pans are popular as water storage units for agricultural field crops irrigation in a country that has just one or two rainy seasons

Pond Liner Calculator

In this pond liner calculator article, we answer the following frequently asked questions

1. How is a dam liner calculated?

The formulae adopted depends  the shape of the water pan. The water reservoir’s dam liner is calculated differently for a circular or oval water pan vis a vis that of a square/ rectangular one. Similarly, a square water tank has a different formulae from a circular one. A water pan with slanting edges has a different formulae from that with straight edges. Whether the water reservoir or tank is for irrigation, domestic or industrial application, the formulae is the same

I. Square/ rectangular water reservoir or tank pond liner calculator

a. Square/ rectangular pond liner calculator for straight edges: Total length in meters: (length + 2depth + 2meters). Total width in meters: (width + 2depth +2meters). The additional 2meters on each side are for the overlap which is tucked in a trench for water reservoirs. For tanks, it’ll be 0.5M. Multiplying the total length with the total width gives the pond liner area in meters

Pond liner installation in a water reservoir with straight edges

Tucking is in a trench all around the water pan

How to trench and tuck your pond liner

b. Square/ rectangular pond liner calculator for slanted edges: Total length in meters: (base length + 2slanting depth + 2meters). Total width in meters: (base width + 2slanting depth +2meters). Multiplying the total length with the total width gives the pond liner area in meters

Pond Liner Calculator: Table

If your totals include a decimal say 120.3sq, round it up to the nearest whole number, in this case 121M sq. The +0.6M in the ‘circular liner’ and is the overlap. So is the 2M in the straight side liner’

“D” is the maximum depth which is the center-most point of the reservoir

II.  Circular pond liner calculator

Diameter + (2height/ depth) + (1meter). The 1meter is the external allowance that goes outside the tank as shown in the image below

A liner in a cylindrical tank

2. How do I calculate how much pond liner I need?

The size of the pond liner is according to the water pan or water tank area. The size of the water pan or tank is by volume, shown as; length by width by depth/ height. The liner size is by area, shown as; length by width. For this conversion, the formulas shown above work

The larger the water pan or tank, the larger the pond liner required

Dam Liner Company In Kenya

Grekkon Limited is the foremost dam liner company in Kenya. From material selection, to welding and installation, our professional teams train growers on all these aspects. It ensures that they make the right choice and why

This is according to the size and nature of their irrigation water reservoirs and tanks. These dam liners in Kenya are UV treated, HDPE geomembrane material in varying thicknesses and weights as tabulated below

The UV treatment reduces radiation damage which is high in tropical countries

A roll of 0.75mm dam liner

Dam Liner Prices In Kenya

Our dam liner cost in Kenya is broken down into; material, welding, and installation. Once a grower procures a dam liner, s/he will have it welded if the width exceeds 8M. If the farmer chooses for us to install, then the cost of installation applies.

How Are Dam Liners Calculated?

Before determining the dam liner size, one must understand the size of the reservoir or tank. This is by measuring the length, width, and depth/ height (for rectangular or square shaped reservoirs/ tanks). For circular or cylindrical tanks/ reservoirs, measure the diameter, and the depth/ height. The reason this is key is because our dam liner material comes in rolls. To make out the shape of the water pan or tank, the dam liner is cut  in large bits from the roll and joined together. This is to create the 2 dimension size of the water reservoir or tank. For example; if the width of the dam liner on the roll is 8M, and the water pan requires a width of 15M. Then 2 pieces, one measuring 8M and another 7M in width from the roll are cut and joined to create the 15M width

How Do I Calculate How Much Dam Liner I Need?

The dam liner calculator is adapted to the shape of the irrigation water reservoir as illustated in the 3 different shapes below

1. Sloped sides reservoir

The slope of the dam wall is shown as slanting length (SL) or slanting width (SW) in the dam liner calculator tabulation shown later in this page

2. Cylindrical circular tanks

3. Straight side reservoirs

Pond Liner Calculator: Table

If your totals include a decimal say 120.3sq, round it up to the nearest whole number, in this case 121M sq. The +0.6M in the ‘circular liner’ and is the overlap. So is the 2M in the straight side liner’

“D” is the maximum depth which is the center-most point of the reservoir

Dam Liner Calculator

How much overhang should a pond liner have?

An overhang is the extra liner material that holds the main liner in the reservoir or tank. This excess material is held against the external wall of the tank, or tucked in a trench all around the reservoir to support the dam liner in place. It is covered with soil or stones in the trench.  Another alternative to trenching is to lay sand bags on it. The weight of the sand bags holds the dam liner in place

After excavation, it is necessary to compress the mould of soil roundabout the water pan before making a trench

See below

Dam Liner Installation

Our dam liner rolls are 8M wide. So for any width beyond this, the additional size has to be welded on. Welding is carried out fully in the ware house for small liners, and partly in the field for large liners. This is to reduce bulkiness during transportation to site

When installing a dam liner in a reservoir, trench round about the reservoir. This anchor trench is where the liner will be tucked for support

The video below shows a farmer in Nandi county recounting the benefits he has received 2 years later after having his dam liner installed by Grekkon Limited

How To Weld Dam Liners

1. Factory welding. Depending on the dam liner size, weld it whole or partially in the factory. The weight and volume of the welded material must be easily portable on site.  The latter factor guides on how much of the dam liner material will be put together in the factory
2. Site  or field welding. This is done on site at the point of dam liner installation. It is the joining together of the partially welded dam liner pieces from the factory. Site welding is done when the entire dam liner could not be wholly put together in the factory. This is as a result of weight or bulkiness, which limits lifting and transportation of the bulky and heavy material. The weight size of the portable material depends on the thickness of the dam liner. The thicker it is, the less it is
3. A wedge welding machine or a heat gun/ heat blower is the equipment that does dam liner welding. A wedge machine is what does it in the factory. The heat gun is highly portable, and so is best for field joinery

Dam liner welding involves melting the liner material under high temperature at the point of joining them. Once melted, the 2 layers are laid one over the other and as they harden, become one unit

Factory wedge welding of a 1mm  thick dam liner

Joining 2 dam liner pieces with a heat gun

Both equipment run on electric power. In off grid electricity locations, Grekkon Limited provides a generator to power the heat gun or wedge welding machine

Dam Liner Company In Kenya: Summary

Every dam liner size is available from our outlets countrywide. Besides supplying and installing liners, our technical team advises growers on;

1. The right size of reservoir for a particular acreage
2. How to properly excavate your reservoir
3. How to select the right dam liner according to ; the reservoir size, surface texture, and one’s budget