School Science Lessons
Food Gardens 3
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Table of contents
9.14.0 Composting, humus, worm farms
6.17.0 Plant fertilizers Plant growth regulators, auxins Plant growth regulators Plant growth regulators, "plant hormones" Auxins Auxins functions Auxins experiments Gibberellins
16.7.0 Herbicides, weedicides Ethylene gas, C2H4, abscission Cytokinins Abscisic acid, C15H20O4 Naphthalene acetic acid, C12H10O2, (NAA) Daminozide, C6H12N2O3, "Alar"

6.17.0 Plant fertilizers Adding fertilizers by broadcasting, banding, top-dressing, side-dressing
6.17.0 Chemical fertilizers, fertilizer trial
6.34 Chemical fertilizers (Primary)
9.14.0 Composting
6.17.1 Fertilizers, straight fertilizers and mixed fertilizers
6.33 Fertilizing soil Grade formula of artificial fertilizers, blended fertilizers
9.9.18 Hydroponics, soil-less culture solutions
6.17.3 Liquid ammonia, anhydrous ammonia fertilizer
6.15.3 Liquid manure Mixed or compound fertilizers Muriate of potash, KCl Organic gardening
35.20.30a Palagonite
5.25: Plant nutrients from plant ash
6.15.4 Seaweed extracts Straight fertilizers, simple fertilizers, NPKS
Sulfate of ammonia
12.14.5 Superphosphate production
6.15.5 Tests for gypsum added to the soil Vermiculite

9.14.0 Composting, humus
Composting (websites)
9.14.0 Composting
9.14.3 Carbon / nitrogen ratio, C/N ratio
9.14.5 Compost inspection
9.14.1 Humus
9.14.2 Organic materials for composting
9.14.6 Start composting for the school garden
9.14.4 Three methods of composting: 1. Heap on the ground, 2. Bin method, 3. Drum method
9.14.7 Worm farms

5.25 Plant nutrients from plant ash
| 6.65.1: Soil nutrients cycle 1
| 6.65.2: Soil nutrients cycle 2
| 6.65.3 Nitrogen cycle
Collect some white ash from burnt wood and bring it to the classroom.
The black ash is carbon.
Show the students the white ash you have collected. Let them taste some.
It tastes a bit salty.
The ash contains plant nutrients.
Show the students a bag of fertilizer let them read the names written on the bag.
Do not let the students taste the fertilizer from the bags.
Plant nutrients are chemicals that plants take in from the soil. Some people call them plant foods.
These chemicals are needed by the plant to keep it alive, to make food, and make the plant body.
If there are not enough plant nutrients in the soil, the plant will be weak, grow slowly, have yellow or brown leaves, and may die.
The most important plant nutrients are as follows:
1. Nitrogen for plenty of strong green leaves
2. Phosphorus for root growth and making fruit
3. Potash (potassium oxide) for healthy plants
Other important plant nutrients are as follows:
4. Sulfur and iron for green leaves
5. Magnesium and calcium for healthy plants
There are other plant nutrients needed in very small amounts, which may be important for some plants, e.g. manganese, boron.
Most plant nutrients originally come from the rocks that formed the soil.
Other plant nutrients in the soil have come from plants that have died then rotted in the soil.
If a soil does not have enough of any plant nutrient, e.g. potash, you say it is deficient in potash.

6.15.3 Liquid manure
Animal manure can be hoed into the surface of the soil where it will act as a mulch and fertilize the soil.
However, if you mix the manure with lots of dry grass it may take nitrogen plant nutrient out of the soil.
Some animal manure such as chicken manure or fresh pig manure may burn small plants if put directly in the soil.
It is best to put animal manure on the compost heap.
You can use animal manure directly on small plants as liquid manure.
Hang a sack inside a drum filled with water and put the fresh manure into the sack.
Nutrients will dissolve into the water in the drum.
Use this to water around the young plants.
You may have to dilute 1 part of manure water with 3 parts of pure water.
This is a good way of using new manure, but it is smelly.

6.15.4 Seaweed extracts
On islands in the South pacific the common opinion is that the best fertilizer is obtained by dragging seaweed,
mostly kelp, onto the land, washing all the salt off it, then burying it in the garden.
Liquid seaweed extracts, e.g. Seasol, Marinure, Maxicrop, Algistim may benefit plants not from their mineral nutrients,
but possibly from organic substances included in the extracts.
The benefits of such extracts may be as follows:
1. increased resistance to fungal disease and insects,
2. higher yields,
3. deeper root penetration and increased nutrient uptake.
For example, the advertising for Seasol Liquid seaweed extract may include claims that it is a "soil revitalizer, growth stimulant and
plant tonic, not a fertilizer".
Such claims should be tested by experimentation.

6.15.5 Tests for gypsum added to the soil
Gypsum may improve the structure of soils that are slippery and sticky when wet, tend to slump and get very muddy during rain,
form a crust on drying, allow only slow entry of water, do not break into anything smaller than large clods during digging.
To test whether a soil may benefit from gypsum, drop a 5 mm diameter crumb of dry soil aggregate into a beaker of deionized water.
Place a similar sample of the soil in the palm of one hand, add deionized water and knead the soil until all of the lumps have been
broken up.
Squeeze some kneaded soil into an aggregate about 5 mm in diameter and drop it into a second beaker of water.
Observe the beaker for an hour and again after 24 hours.
Some aggregates remain unchanged, even after 24 hours.
Some aggregates fall apart during the first hour, but the smaller aggregates so formed remain where they fall.
Other aggregates slowly disperse into the water,
whether they fall apart or not.
A surrounding "halo" of clay particles forms around the aggregate then spreads to form a cloudiness in the water.
Gypsum will not improve the structure of a soil where the aggregates remain unchanged or fall apart without dispersion.
The more cloudy the water, and the more rapidly the cloudiness develops, the greater will be the benefit of adding gypsum to the soil,
and the more gypsum will be needed.
Use 0.5 - 1 kg of gypsum per square metre.
Beside improving the structure of the soil, gypsum is a good source of calcium and does not change the pH of the soil.

6.17.0 Chemical fertilizers, fertilizer trial
12.14.5 Superphosphate production
1. Chemical fertilizers are made in factories.
Some are made from minerals that occur naturally, and are later ground to a powder and sometimes treated with chemicals, e.g.
ground rock phosphates and superphosphate.
Other fertilizers are chemicals in chemical factories e.g.
sulfate of potash (potassium sulfate).
In this topic you will refer to chemical fertilizers as "fertilizers".
2. Some people think that students should not be learning about imported fertilizers.
However, many tropical soils are lacking in certain plant nutrients, e.g.
potash, and the use of a small amount of these fertilizers can greatly increase the yield of the food crops.
Imported fertilizers are costly but if they are used according to the recommendations of the Department of Agriculture,
and are stored properly they should pay for themselves in the increased value of the crop yield.
Do some fertilizer trials.
Then you can make your own decision about whether it is cost effective to buy and use imported fertilizers.
3. A good design for a fertilizer trial is as follows:
Table 6.17.0
| Block 1 | Block 3 |
| Block 2 | Block 4 |
In each block plant 20 cuttings of potato.
Blocks 1 and 4 are experimental blocks.
Put one teaspoon full of fertilizer in the soil around each cutting.
Blocks 2 and 3 are control blocks, so do not use any fertilizer.
Harvest each block separately and weigh the potato.
Compare the weight of potato from Blocks 1 and 4 with the weight from Blocks 2 and 3.
Compare the value of the harvests if they were sold.
Generally speaking, it pays to use fertilizer if the use of fertilizers can at least double the yield, i.e.
weight of blocks (1 + 4) / weight of blocks (2 + 3) / 2.
4. Use fertilizer to make a profit.
Profit = (returns from Blocks 1 and 4) to (returns from Blocks 2 and 3) to cost of fertilizer used.
Cost of fertilizer in bags = (cost of fertilizer + freight) × (weight of fertilizer used / weight of whole bag of fertilizer)
5. The following is an example of a lesson that you could give on chemical fertilizers.
You will need a fertilizer bag.
This lesson could be followed by a lessons on how to put fertilizers in the soil.
1. Show the students where chemical fertilizer has been used in your school food gardens, or ask them whether they have seen it used
in a plantation.
2. Show the students a bag of fertilizer.
Let them read: 2.1 The name of the factory that made it, e.g.
CFL Consolidated Fertilizers Limited, 2.2 The weight of the fertilizer, e.g.
50 kg, 2.3 the grade formula e.g. NPK 12:4:19.
This means that 100 grams of the fertilizer contains 12 grams of nitrogen, 4 grams of phosphorus and 19 grams of potassium.
3. Ask the students whether they think it is a good idea to use this imported fertilizer.
Ask them to tell you the advantages and disadvantages of using it.
1. Fertilizer provides plant nutrients.
2. Fertilizer increases the yield and the value of a crop.
1. Fertilizer is costly.
2. If fertilizer is not used properly it is wasted.
4. Let the students put some fertilizers in their hands.
Do not let them taste it but they can smell it.

6.17.1 Fertilizers, straight fertilizers and mixed fertilizers
1. Simple or straight fertilizers contain only one of the main plant nutrients and usually some other plant nutrient.
Single superphosphate contains mainly phosphorus and it also contains some sulfur and calcium. Muriate of potash, KCl, contains potassium and chlorine.

2. Mixed fertilizers contain a mixture of simple fertilizers so that nitrogen, phosphorus and potassium may all be present as well as
other plant nutrients.
These fertilizers can be mixed before putting them in the soil or they can be bought already mixed, e.g.
"Thrive" and "Zest".

3. Compound (or composite) fertilizers contain nitrogen, phosphorus and potassium in various forms of chemicals such as ammonium
phosphate nitrate.
They also contain other plant nutrients.
Some of these are "slow release" fertilizers, e.g. IBDU, which slowly releases urea into the soil as it dissolves on the soil water.
IBDU, isobutylidenediurea (CH)2CHCH{NHC(O)NH2}2
"Osmocote", slowly releases an NPK mixture.

4. Some fertilizers have high concentrations of plant nutrients and are called high analysis fertilizers, e.g. triple superphosphate.
Some fertilizers are made in the factory as granules or pellets.
They give plants the correct mixture of plant nutrients at all times and are thus better than mixtures. Grade formula of artificial fertilizers, blended fertilizers
If the fertilizer contains 13% nitrogen, 13% phosphorus and 21% potassium,
100 grams of the fertilizer would contain 13 g nitrogen, 13 g phosphorus and 21 g potassium, the grade formula is NPK =13:13:21.
Other examples of the grade formula of artificial fertilizers:
Muriate of potash (NPK = 0:0:50),
Superphosphate (NPK = 9:0:0),
Sulfate of ammonia (NPK = 21:0:0),
Urea (NPK = 46:0:0).
The term "potash" applied to mixed fertilizers refers to "K2O equivalent", but not to K2O itself, because it is not included in a mixed
1. The contents of fertilizers are shown by a grade formula that uses the chemical symbols of the primary plant nutrients NPK.
This is used in two ways, e.g.
The old way listed the contents of potassium and phosphorus as their oxides.

2. Previous formula
100 g fertilizer contains 13 g Nitrogen, 13 g Phosphorus Oxide and 21 g Potash (Potassium Oxide).
The fertilizer would be shown as: NPK = 13:13:21.

3. Current formula
The current formula lists the contents as the elements nitrogen, phosphorus and potassium.
If the fertilizer contains 13% Nitrogen N 13%, Phosphorus P 21%, and Potassium K. 100 grams of the fertilizer would contain
13 g nitrogen, 13 g phosphorus and 21 g potassium.
The fertilizer is shown as NPK =13:13:21.
Fertilizers containing a high concentration of plant nutrients and are called high analysis fertilizers, e.g.
triple superphosphate.
Some fertilizers are manufactured as granules or pellets that give the correct mixture of plant nutrients at all times and so are better
than mixtures.
Examples of the NPK grade formula of fertilizers
Fertilizer, N, P, K
1. Muriate of potash | 0 N | 0 P | 5 K |
2. Superphosphate | 0 N | 9 P | 0 K |
3. Sulfate of ammonia | 21 N | 0 P | 0 K |
4. Triple superphosphate | 0 N | 20 P | 0 K |
5. Urea | 46 N | 0 P | 0 K | Adding fertilizers by broadcasting, banding, top-dressing, side-dressing
The 4 methods of adding fertilizer to the soil
1. Broadcasting
The fertilizer is spread over the surface of the soil by hand or by machine.
It should then be dug into the soil using a hoe or plough because if left on the surface nitrogen plant nutrient may be lost as ammonia gas.
Fertilizer dug into the soil about 2 weeks before the crop is sown is called a base-dressing.
2. Banding
The fertilizer is placed below the surface of the soil by hand or by machine.
A furrow is dug between the rows of seeds at a depth of about 2 cm deeper than the seeds, the soil is then turned to cover the band
of fertilizer.
Banding is done at about the same time as the seed is sown.
3. Top-dressing
The fertilizer is spread after the crop has been sown.
This is usually done with nitrogen fertilizer to provide extra plant nutrient at certain times to make more shoots and leaves.
However, nitrogen plant nutrient may be easily washed out of the soil so it is best to add some of the fertilizer by banding at sowing
time and add the rest by top-dressing when the shoots and leaves are growing.
4. Side-dressing
The fertilizer is placed between the rows by banding or placed under the plants and watered in after the crop has been growing for
some time.
This is done for maize (corn) vine crops and tree crops to increase the yield of fruit. Straight fertilizers, simple fertilizers, NPKS
| Common name | Chemical formula | Approximate composition |
1. Nitrogen fertilizers
Sulfate of ammonia | (NH4)2SO4 | 21% N and 24% S |
Nitrate of potash | KNO3 |38% K and 13% N |
Nitrate of soda | NaNO3 | 16% N |
Urea | CO(NH2)2 | 46% N |
2. Phosphorous Fertilizers
Single superphosphate | Ca(H2P04)2 + CaSO4 | 0.9% P, 10% S, 20% Ca |
Triple superphosphate | Ca(H2PO4)2 | 9% P, 02% S, 16% Ca |
MAP, mono ammonium phosphate | NH4H2PO4 | 22% P, 12% N |
DAP, diammonium phosphate | (NH4)2HPO4 | 20% P, 18% N |
3. Potash Fertilizers
Muriate of potash | KCl | 50% K |
Sulfate of potash | K2SO4 | 40% K, 16% S |
Potassium nitrate | KNO3 | 38% K, 13% N |
4. Magnesium sulfate | MgSO4 |
5. Sulfur | S | 99% S |
6. Gypsum | CaSO4.2H2O | 18% Ca and 14% S | Mixed or compound fertilizers
They have many different compositions, e.g.
12% N, 4% P, 19% K, 10% S (high in potassium and sulfur), 12% N, 14% P, 10% K, 3% S (high in phosphorus).
Osmocote is made with many different compositions but IBDU contains 33% Nitrogen.
Only certain forms of nitrogen fertilizer are suitable for controlled release in the tropics.
Most dump their nitrogen.
The estimated lasting period of 0.7 to 2.6 mm granules of IBDU depends on pH, water holding capacity of the soil and temperature. Organic gardening
Organic farming, commercial websites
"What is organic gardening?" Adapted from Brisbane Organic Growers Inc.
"Gardening without the use of artificial fertilizers and toxic chemicals" is probably the simplest definition but also the least satisfying.
However, this definition implies that you can just sit back and leave it all to nature.
This incorrect belief in turn, leads to the mistaken misconception that organic gardens are wild, unkempt places where every cabbage
is riddled with holes and every rosebush is blighted with mildew.
Organic gardeners do not just leave their gardens to nature; they use all the methods, techniques and products at their disposal to
work, as far as possible, with nature.
1. Stop using chemicals.
Safely dispose of all your chemicals, fertilizers and pesticides so that you are not tempted to use them.
This is important as the harm they do will hamper your efforts to build up an organic system.
2. Care for the soil, think of the soil in your garden as a living environment in which earthworms and beneficial bacteria convert
organic material and inorganic soil minerals into plant food.
Fertile, humus rich soil is a storehouse of plant nutrients made available to plants as required and in balanced form.
Soil structure is important.
Soil must be friable to permit air and water to enter and to allow plant roots to forage through it.
This is achieved by the addition of organic material as compost, mulches and green manures.
Composting is possibly one of the most important activities of the organic gardener.
It is an extension of nature's own system of recycling vegetable matter and returning it to the soil.
It is a perpetual cycle that has been going on in nature since time began and there is no better way of keeping the soil in your garden
fertile and healthy.
Other materials to benefit the soil that organic gardeners use include animal manures, blood and bone mixture, seaweed extract, fish
emulsion, dolomite and rock minerals, to name a few.
3. Encourage nature.
Strong vigorous plants will resist disease and insect attack.
The most effective agents operating to control insect pests are those that occur in nature, the parasites, predators and diseases of the
Natural predators of insect pests are often reduced to insignificant numbers by using insecticides that are usually non-selective and
therefore eliminate both the pests and predators alike.
Moreover, many insect pests have developed immunity to one or more of the insecticides that render these chemicals ineffective in
controlling them.
The organic gardener does all he or she can to encourage these predators that include birds, frogs, lizards and many beneficial insects
such as ladybirds, lacewings, preying mantis and several species of wasps.
The red wasps seen hovering over the lawn and darting in and out of shrubs and vines during summer months are natural predators of
lawn grubs and caterpillars and will keep these pests well under control.
Magpies that are often seen patrolling suburban lawns and gardens are also busy foraging for grubs in lawns and larvae in soil.
Bacillus Thuringiensis, sold as "Dipel" is a bacterial disease of caterpillars and is useful in controlling this pest.
It is quite harmless except to caterpillars.
Crop rotation, companion planting and the use of disease resistant varieties of plants are some of the many methods used by organic
gardeners for pest control.
Changing from chemical to organic gardening and farming means discovering how nature does things and adopting her methods.
For after all, she has been gardening a lot longer than humans.
It is a healing process for both the garden and the gardener.
Aggressive attitudes that seek to subdue nature and bend her will are replaced by peaceful co-operation and coexistence, and with
nature as your ally. Muriate of potash, KCl
When muriate of potash fertilizer (potassium chloride), is put in the soil, it adds to the soil potassium ions, K+ and chloride ions, Cl-.
These ions become attached to the clay particles and organic matter particles in the soil.
However, if the soil is too acid or too alkaline, the large number of H+ ions or OH- ions will interfere with the attachment of fertilizer
ions to soil particles.
They may cause the fertilizer ions to be held too strongly to the soil particles.
If this happens, the nutrient ions cannot be used by the roots of plants and you say that the nutrients are unavailable to the plants.
Potassium chloride is highly soluble and its high salt index may disrupt osmotic gradients in the rhizosphere and so harming soil bacteria
and other soil micro-organisms.
An application of 100 kg / hectare of muriate of potash produces about 20 ppm of chloride in the soil solution to a depth of 75 mm.
So although chloride can be easily washed out of the soil, some farmers are using alternatives to muriate of potash, e.g.
potassium sulfate, potassium oxide, potassium carbonate and mono potassium phosphate, MK.

Commercial soil pH test kit
Soil, (Commercial)
1. For the best growth of plants it is essential that the acidity (measured by pH) of the potting mix or soil is suitable for the plants you
want to grow.
Most soils are either slightly acid or slightly alkaline.
A few soils are neutral (between acid and alkaline).
Some soils are very acid and some are very alkaline.
Neutral soils have a pH of 7.
Acid soils have pH values < 7.
Alkaline soils have pH > 7.
Plant growth is affected by soil pH.
Few plants grow well in soils with pH values below 4.5.
Plants from very acid soils grow best in soils of pH 4.5 to about pH 6, but do not grow well on neutral and alkaline soils.
Most other plants grow best in soils of pH values 6 to 7.
Plants from alkaline soils will grow on slightly acid soils, but they will also grow well on alkaline soils.
Most plants grow well in potting mixes when the pH of the mix is in the range 5.5 to 6.5.
Plants from very acid soils prefer a potting mix with a pH in the range 4.5 to 5.5.

2. Plants adapted to acid soils are often unable to get enough of the essential nutrients iron and manganese from alkaline soils.
Their young leaves show yellowing (chlorosis) and growth is poor.
Severe deficiency leads to death.
By contrast, plants adapted to alkaline and slightly acid soils can be harmed by the amounts of dissolved aluminium and manganese
present in very acid soils.
They probably cannot take up enough of the essential element calcium.

3. Raise soil pH by adding agricultural lime or dolomite.
A 1:1 mixture of the two may be best.
Lime / dolomite (g / m2), To raise pH of the top 10 cm about 1 pH unit.
Table 6.17.6ZZZ
Soil type | Lime / dolomite | 100 (g / m2)
Sands | 100 g / m2 |
Loam | 200 g / m2 |
Clay soils | 300 to 400 g / m2 |
Organic soils |600 g / m2 |

Lower the pH of slightly alkaline soils (pH below 7.5) with agricultural sulfur.
Sulfur (g / m2) To lower pH of the top 10 cm by about 1 pH unit.
Table 6.17.7
Soil type | Sulfur |
Sands | 25 g / m2 |
Loam | 50 to 70 g / m2 |
Clays | 100 g / m2 |
The large amounts of solid lime often present in alkaline soils with pH values higher than about 7.5, make it almost impossible to make
these soils acid.

4. Change potting mix pH.
The mix must be moist enough to use for potting.
Raise pH with dolomite.
Add 1 to 1.5 g/L of mix to raise pH by about one unit.
Lower pH with sulfur.
Add 0.3 g/L to lower pH by about one unit.
Check the pH again after two weeks storage and add more as needed.
The pH of mix in pots should be checked every few months, because most fertilizers produce acidity.
Raise pH with a suspension of hydrated lime (builders' lime).
Suspend 5g (a heaped teaspoon) in a litre of water.
Pour the suspension onto the mix in the pot.
Use 200 mL for each litre of the mix.
(A 130 mm pot contains about 1 litre of mix.) Pot the plants again if the pH of the mix is below 4.5.
Lower pH with a solution containing 2 g of iron sulfate per litre of water.
Apply 200 mL per litre of mix and within two minutes heavily water the pot to remove excess salt.
Wait for one week, check mix pH and add more iron sulfate if needed.
Preferred pH ranges
4.1 Soils of pH 4.5 to 6 potting mixes of pH 4.5 to 5.5
Camellia, Rhododendrons, Azalea, Gardenia, Erica, Macadamia, Juniper, Spruce, Japanese Maple
4.2 Soils of pH 5.8 to 7.5 potting mixes of pH 5.3 to 6.5
Most vegetables, bedding plants, commonly grown shrubs and trees.
4.3 Soils of pH 7 and higher potting mixes of pH 6 to 6.7
Many cacti and succulents.
Plants native to arid areas.
Grow roses and citrus that have been grafted onto rootstocks that tolerate these soils.

5. Directions for using the colour chart for soil pH
Careful sampling is essential.
For a garden bed, take at least 5 samples from holes dug in different parts of the bed.
Each sample is to extend from the surface to a depth of 10 cm.
Test each sample separately.
For farm paddocks, take at least 20 samples from each area.
Mix samples together thoroughly and test as one sample.
For bought and home made potting mix, thoroughly mix the bulk lot.
For mix in a pot, first knock the root ball from the pot.
Remove a wedge of mix representing the whole depth of the root ball.
Mix thoroughly.
For a mix in large tubs, dig down the side of the root ball as deeply as is possible.
Thoroughly mix the sample removed.

6. Measure pH
Place a level teaspoon of mixed soil or potting mix on the test plate.
Add 3 to 5 drops of indicator liquid and stir with the rod provided.
Dust the paste with the white powder provided.
Wait one minute.
Read from the colour card the pH value of the colour nearest to that of the sample.
The test kit contains one bottle of pH dye indicator and one bottle of barium sulfate solution.
The test kit is manufactured in Australia by Mantic Pty.
Ltd., 30 Jonah Drive, Cavan, South Australia 5094, Australia.

6.17.3 Liquid ammonia, anhydrous ammonia fertilizer
Liquid ammonia, commonly called anhydrous ammonia, is ammonia gas in liquid form, .
It is the cheapest source of ammonia fertilizer but it must be stored under high pressure and injected into the soil under pressure
where it dissolves in the soil water.
It is a dangerous chemical that must be stored and handled under high pressure, requiring specially designed and well maintained
In addition, to ensure their safety, workers must be adequately educated about the procedures and personal protective equipment
required to safely handle this product. Plant growth regulators
Plant growth regulators is a term that includes auxins, gibberellins, cytokinins, ethylene generators, growth inhibitors (to stops
growth and promote flower production by shortening internodes), and growth retardants (to slow growth).
Plant growth regulators are also called plant hormones, phytohormones, plant growth substances, but the term "plant hormone"
is not approved by some horticulturists and chemists. Auxins Auxins Experiment
1. Compounds are called auxins if they are synthesized by plants and have a similar activity to indole-3-acetic acid, C10H9NO2, (IAA).
Indol-3-acetic acid was the first auxin to be isolated from plants, is the most abundant, and so it is the basic auxin.
It is an isomeric acetic acid derivative of indole and important plant "hormone" (heteroauxin) that controls plant growth.

2. Auxins stimulate cell elongation, cell division in the cambium, differentiation of phloem and xylem, root initiation on stem cuttings,
growth of flower parts, fruit setting, production of ethylene, and suppress growth of lateral buds and delay fruit ripening.

3. Auxins were discovered by Dutch botanist Fritz Went (1903-1990), who in 1928 isolated a plant growth substances by
placing agar blocks under oat (Avena), coleoptile tips, removing them and placing them on decapitated oat stems that then
resumed growth.
The "Avena curvature test" was base on the observation that the curvatures of the coleoptiles were proportional to the amount of
growth substance in the agar.

4. An auxin is the active ingredient in a commercial root formation compound used to stimulate root formation in cuttings used for
vegetative propagation, e.g. indole-3-butyric acid, C12H13NO2, (IBA) ("Rootex-L, hormone rooting liquid").

5. Auxins cause the following responses:
1. Stem bends toward a light source (phototropism)
2. Root grows downward in response to gravity (geotropism)
3. Adventitious roots form
4. Apical meristem is dominant over lateral meristems
5. Flower formation, fruit set and fruit growth.

6. The four auxins synthesized by plants are as follows:
(1.) Indole-3-acetic acid, indole acetic acid, IAA,
(2.) 4-Chloroindole-3-acetic acid,
(3.) Phenylacetic acid,
(4.) Indolebutyric acid, indole-3-butyric acid, IBA, stimulated root growth.

7. Five of the many synthetic auxins are as follows:
(1.) 2,4-Dichlorophenoxyacetic acid, 2,4-D, herbicide,
(2). α-Naphthalene acetic acid, α-NAA, active constituent of commercial rooting powders,
(3.) 2-Methoxy-3,6-dichlorobenzoic acid, dicamba, herbicide,
(4.) 4-Amino-3,5,6-trichloropicolinic acid, picloram, herbicide,
(5.) 2,4,5-Trichlorophenoxyacetic acid, 2,4,5-T, herbicide. Auxins functions
1. Stimulates cell elongation, cell division, differentiation of phloem and xylem, root initiation on stem cuttings, lateral root
development, growth of flower parts, production of ethylene
2. Affects phototropism
3. Apical bud suppresses growth of lateral buds
4. Delays leaf senescence
5. Affects leaf and fruit abscission by ethylene stimulation
6. Induce fruit setting and growth, delays fruit ripening
Abscisic acid (ABA), C15H20O4 (ABA) has the following functions:
1. Stimulates the closure of stomates during water stress.
2. Inhibits shoot growth.
3. Induces seeds to synthesize storage proteins.
4. Inhibits the effects of gibberellins.
5. Induces and maintains dormancy.
6. Induces responses to wounding. Auxins Experiment
See diagram 9.1.7: Auxin experiment
Put oat, barley or wheat grains in a flat dish containing tap water.
The next day, sow them in a pot.
When the seedlings are 3 cm high, cut off 10 mm from the tips of the two thirds of the shoots.
Leave one third of the seedlings not treated as a control.
Dissolve 1 g of gelatine, with heating, in 20 mL demineralized water.
Use this solution to stick back the shoot tips on half the cut seedlings.
Note any further growth.
The seedlings without a shoot tip stop growing.
The seedlings with the shoot tips stuck on again continue to grow almost as much as the control seedlings.
The growth substance, auxin, diffuses out of the replaced tips through the gelatine into the cut end, allowing the plant
to continue to grow.
Under the influence of light, substances form in plants that, in specific concentrations, trigger cell division and cause elongation.
These growth substances (auxins) are found especially on buds and root tips. Gibberellins
Gibberellic acid, C19H22O6 (GA3), plant growth hormone, Toxic if ingested
Gibberellins stimulate cell division and elongation, flowering in response to long days, stem elongation, flowering in response to long
days, production of a-amylase in germinating cereal grains, maleness in dioecious flowers (sex expression), release of dormancy
in some plants, induce germination, parthenocarpic (seedless) fruit development, senescence delay in leaves and citrus fruits.
However, active gibberellins show many physiological effects, each depending on the type of gibberellin present and the species
of plant. Ethylene gas, CH2, abscission
Ethylene gas, CH2, stimulates fruit ripening, break of dormancy, shoot and root growth and differentiation (triple response), leaf
and fruit abscission, flower opening, flower and leaf senescence.
Abscission is the natural separation of a plant part, e.g. leaf, fruit, flower, seed, from the plant, leaving an abscission layer of cork
cells to prevent water loss.
Deciduous plants lose all their leaves by abscission before winter but evergreen plants lose their older leaves continually. Cytokinins
Cytokinins, stimulate cell division, shoot initiation, bud formation, growth of lateral buds, leaf expansion.
The hundreds of cytokins include the natural compounds adenine and zeatin, and the synthetic compounds kinetin and
benzyladenine (BA).
The response will vary depending on the type of cytokinin and plant species. Abscisic acid, C15H20O4
Abscisic acid stimulates the closure of stomates during water stress, seeds to synthesize storage, dormancy, responses to wounding.
Inhibits shoot growth, the effects of gibberellins. Naphthalene acetic acid, C12H10O2 (NAA)
Purchase: 1-Naphthaleneacetic acid, plant cell culture tested, BioReagent, 95%, crystalline, α-Naphthaleneacetic acid,
1-Naphthylacetic acid, NAA, Naphthalene acetic acid (NAA) stimulates root growth and slows respiration. Daminozide, C6H12N2O3, "Alar"
Purchase: Daminozide, Succinic acid mono(2, 2-dimethylhydrazide), HO2CCH2CH2CONHN(CH3)2, butanedioic acid, "Alar",
B-Nine, Alar, Kylar, SADH, B-995, aminozide, b-9, Cycocel, "Arest".
Daminozide controls the vegetative and reproductive growth of orchard and enhances shorter and more erect peanut vines.
However, the use of "Alar" for food production in now banned in USA.

9.14.0 Composting
9.14.3: Carbon / nitrogen ratio
1. Before teaching this lesson, ask a field officer from the Ministry of Agriculture about compost heaps.
In some places the Department of Agriculture does not approve compost heaps because they can be home for insect pests,
e.g. the rhinoceros beetles that attack coconut.
Composting is just a way of speeding the natural processes of rotting under controlled conditions using:
1. organic material,
2. micro-organisms, moisture and oxygen and using this rotting process to provide plant nutrients for the crops in your gardens.
When an animal or plant dies, bacteria and fungi make the chemicals in them breakdown into simpler chemicals and gases are given off.
This process is called rotting or decomposition.
Bacteria and fungi can convert these simpler chemicals to complex organic compounds, e.g. humus, that can return to the soil as plant
nutrients and be used by plants again.
Composting is a natural way of fertilizing but composting may bring weed seeds and pests into the soil.

2. When preparing for composting the headmaster must decide on a school policy that ALL waste materials should be saved for the
compost heaps.
In the kitchen, peelings and food scraps are all saved and kept separate from rubbish, e.g. tins and boxes.
A few bashed iron tins may add iron plant nutrient to the compost or be used to trap air in the compost heap.
No student is allowed to burn heaps of dead leaves, cut grass, or weeds.
All this material must be taken to the compost heap each day.
Two students are appointed to look after the compost heaps every day during school maintenance time.

3. Select a well drained area of soil fairly near the kitchen and kitchen gardens, but remember that most compost heaps smell a bit.
Dig up the soil to loosen it.
You will need a shelter with a roof of leaves which will protect the compost from the sun and heavy rain but allow some water to drip
You may need to put up a fence to keep animals away.

4. The bottom layer of the compost heap should be coarse material, e.g. plant stems, placed on the soil.
This allows air to move up into the heap and also allows earthworms to come up into the heap from the soil.
Most people then build up a heap in layers of high nitrogen and low nitrogen material:
1. first soil then corn stalks,
2. then sweet potato peelings,
3. then cut grass then kitchen scraps,
4. then cut weeds,
5. then old bean plants,
6. then pig manure,
7. then dead leaves then cut grass.
The heap should be about one metre x one metre in area and one metre high.
Some people add a top layer of five cm of soil or you cover the heap with old bags or black plastic.
This keeps off flies and keeps in bad smells.
If the material is chopped up before adding to the heap the compost will be made more quickly and will be better for the garden.
There are some compost making machines which chop the plant material.
Do not add paper, rags, sawdust, tea leaves, or pesticides to the compost heap.
Do not add tufts of grass with the soil sticking to the roots, this will make the compost heap hard to turn and will keep out the air.

5. The compost heap should be sprinkled with water to give the right amount of moisture.
To test for this, take a handful of compost from inside the heap and squeeze it, a few drops of water should come out.
The heap is too dry if you cannot squeeze out water and there is a lot of greyish dust from fungus.
The heap is too wet if the compost is sloppy and has a bad smell.

6. To make good compost the heap must be turned over with a fork to mix all the materials together and let in the air.
The heap will become quite hot due to the activity of the bacteria and fungi).
Turning the compost will also kill weak seeds and insect pest.
If the temperature of the heap rises above 60oC the bacteria and fungi) may die but the temperature may be kept down by more
turning or making smaller heaps.
Remember that dry grass mulch or dry compost which is not rotten may take nitrogen plant nutrient out of the soil.

7.0 Two methods of teaching about composting
7.1 Begin right at the beginning and get students to collect plant and animal material, make a first compost heap,
examine the heap every week to see what happens to material, and decide when the compost is ready to be put in the garden.
7.2 The above method takes a long time to teach, is hard to organize and at the end the students may forget what happened at the beginning.
A better way of teaching composting may be to get regular composting work going during school maintenance time,
and when you think the student workers are doing it properly give a lesson on composting.
Demonstrate how to do the three composting jobs then let the students do them.
1st composting job: Place layers of new material on the heap until it is about one metre high and keep the heap damp.
2nd composting job: The material has packed down and there is still time for turning it so turn the compost to let the air get in and
keep the heap damp.
3rd composting job: The compost is dark coloured, crumbly and ready to put in the garden.
Dig out the compost and dig it into the soil.
Let the students put their hands in each heap, take out a handful, squeeze and smell it.
Ask them to describe what they see, feel and smell.
Ask the students whether the compost is too wet or too dry.

9.14.1 Humus
Soil bacteria and fungi turn plant organic matter, e.g. leaves, into a dark form of organic matter called humus that has a very
complicated composition.
Humus includes humic acids, fulvic acids and miscellaneous dark organic compounds called humin.
Humic acids are dark brown to black complex aromatic molecules linked together by amino acids, amino sugars, peptides and
aliphatic compounds.
Fulvic acids are yellow brown aromatic compounds linked to aliphatic compounds.
Natural grassland compost is mainly humic acids and natural forest compost is mainly fulvic acids.
Composting puts plant nutrients in the soil that the plants can use easily, improves the soil structure, allows the soil to store more water
and is a cheap way of fertilizing the soil.
Soil organic matter includes decomposing plants, animals and animal waste products and products of this decomposing process,
organic colloids, the binding agents that help create soil aggregates, and nutrients used for plant growth, e.g. nitrates, phosphates.
Humus is the fully decomposed organic matter.
Organic matter is important for plant growth.
Organic matter is a source of plant nutrients.
When broken down, organic matter can hold on to water and nutrients, and stop nutrients from being leached away.
Organic matter improves soil structure.
Organic colloids bind individual mineral particles together into soil aggregates, allowing more water to enter a clay soil and improving
the water holding capacity of a sandy soil.
Crop residues and trash from previous crops retained on the surface of the soil help to control soil erosion.
Loss of organic matter is caused by continuous cropping, removal of vegetation, e.g. hay, burning crop stubble, too much cultivation.
Organic matter can be added to the soil by:
1. adding animal manure,
2. growing a green manure crop and ploughing it in, e.g. cow pea, mung bean, buckwheat, millet, soybean, fava bean, fenugreek,
lupins, woolly pod vetch,
3. resting an area of soil from cropping, e.g. crop rotation.
Rotate crops with a pasture phase to allow both build up of surface cover and an increase in soil organism numbers.
Soil organisms are responsible for the breakdown and final decay of organic matter.
The larger organisms, e.g. earthworms, eat organic matter and so speed up the breakdown process.
They also make tunnels through soil by which water and air can enter.
Soil bacteria and fungi may use each other's waste products so that nutrients are passed around and made available to plants.
Decomposers breakdown dead plant and animal material to simple substances that can be used as nutrients by living plants.
Nitrifying bacteria convert ammonium produced during decomposition into nitrates in the soil.
Nitrogen-fixing organisms that convert nitrogen in the soil air into nitrates include Rhizobium in small nodules on the roots of legumes
and blue-green algae in wet soils.
However, some denitrifying bacteria in wet soils convert nitrates back into nitrogen gas and so make nitrogenous substances
unavailable to plants.

9.14.2 Organic materials for composting
Collect plant and animal material, e.g. animal manure, fish scraps, food scraps, fallen leaves, cut grass and weeds, washed seaweed.
Do not use paper, rags, sawdust, wood, diseased plants, strong chemicals, insecticides, human wastes, i.e. urine, faeces, "night soil",
or tufts of grass with the soil sticking to the roots because this will make the compost heap hard to turn and will keep out the air.
You can increase the speed of making compost by using "compost starters" that contain the needed bacteria, but these products are
usually quite expensive.

9.14.3 Carbon / nitrogen ratio
The organic material must have a suitable carbon / nitrogen ratio.
The bacteria and fungi that make the compost need certain amounts of both carbon and nitrogen nutrients.
If there is too much carbon and not enough nitrogen they will breakdown the material very slowly, and the compost made may even
take nitrogen plant nutrient out of the soil, called nitrogen draw down.
If there is not enough carbon and too much nitrogen much the nitrogen will be lost as ammonia gas.
So a compost heap should contain a mixture of high nitrogen material and low nitrogen material.
Sawdust, rags and paper have very low amounts of nitrogen and should not be used unless they have been left out in the rain for long.
Adding urea or ammonium sulfate can increase the nitrogen in the compost.
Do not add lime to compost heaps because it increases the loss of nitrogen as ammonia gas.
How much nitrogen in materials:
1. Very high nitrogen: chicken and pig manure, urine
2. High nitrogen: deep litter, fish scraps.
3. About right nitrogen: waste food, fruit and vegetable peelings, seaweed.
4. Low nitrogen:, cut grass, weeds, crop residues.
5. Very low nitrogen:, leaves, sawdust, rags, paper.
You can sprinkle a little nitrogen fertilizer over the compost layers but this is expensive.
Composting may decrease the nitrogen plant nutrient if the compost is not made properly and there is too much carbon and not
enough nitrogen in it.

Approximate values of the Carbon / Nitrogen ratio, [C / N ratios]
The ideal ratio is 20-30 parts of carbon to one part of nitrogen.
Material with too much carbon has a slow decomposition and seems to just stays there, e.g. sawdust.
Material with too much nitrogen has a quick but smelly decomposition.
The excess nitrogen may be converted to ammonia which dissipates into the air, e.g. wet green grass clippings.
Sawdust < 500:1, Paper 170:1, Straw 100:1, Leaves < 80:1, Bagasse (sugar cane residue) 50:1, Seaweed 25:1,
Horse manure 25:1, Legume or grass hay 25:1, Rotted manure 20:1, Grass clippings 20:1, Leafy green weeds 20:1,
Food waste 15:1, Humus l0:1, Poultry manure 7:l, Blood and bone manure (commercial product): 7:l, Fish waste 5:1.

9.14.4 Three methods of composting
1. Heap on the ground
Make compost heaps about 2 m × 2 m long and ×1 m high.
Build the compost heap by making layers of dead leaves, black soil, and some manure or other nitrogen containing substances.
Do this again so you have many thin layers one on top of the other.
Then water the compost heap to make it damp.
Then cover it with dead coconut leaves to keep the hot sun from making it dry.
After five weeks, turn the compost layers over onto another place.
Mix up all the layers.
Then water it again and cover it with coconut leaves.
After another five weeks, do this again.
In about three months the compost will be ready to use.
If it has been a dry time, it may take a little longer to be ready.
If you put meat scraps or dead animals in the compost heap, they will attract wild animals and birds and cause extra smells.
Some bacteria and fungi live better in the air and some live better without air.
Those that like air can produce compost quickly in heaps above the ground, but some nitrogen is lost as ammonia gas.
The bottom layer of the compost heap should be coarse material, e.g. plant stems, placed on the soil.
This allows air to move up into the heap and allows earthworms to come up into the heap from the soil.
Most people then build up a heap in layers of high nitrogen then low nitrogen material, e.g. first soil then corn stalks then sweet potato
peelings then cut grass then kitchen scraps then cut weeds then old bean plants then pig manure then dead leaves then cut grass.
Some people add a top layer of 5 cm of soil or they cover the heap with old bags or black plastic.
This keeps off flies and keeps in bad smells.
If you chop up the material before adding to the heap you will make the compost more quickly and it will be better for the garden.
Some compost making machines chop the plant material.
You make the best compost in a heap that you turn over every three days for three weeks.
However, most people are too lazy to do this and use the bin method.

2. Bin method
Bins are walled heaps on the ground.
Build bin walls in the shape of the letter E with galvanized iron, wooden boards or chicken wire.
A chicken wire floor can let air in the bottom of the compost heap.
Another method is to cut the bins out of the side of a hill.
This provides three earth walls for each bin and a front door can be made of boards.
Fill the first bin with layers of material and cover with soil.
This may take about a week. One week later you fork the heap in the first bin into the second bin.
Use the fork to throw the material up lightly and let it fall into the second bin.
Cover the heap in the second bin lightly with soil.
Four weeks later turn the contents of the second bin into the third bin and cover with soil.
After another four weeks, the compost should be ready to put in the soil of the garden.
Start the compost heap in one compartment and every two weeks use a spade to turn all the compost into the other compartment.
In this way you regularly turn the compost and you have a neat storage system.
When you concentrate green grass in a pit and seal it from the air, the anaerobic bacteria decompose it to mainly lactic acid and
acetic acid to produce pickled grass called silage with pH 4-5.
Compost pits are not satisfactory because there is no air for the aerobic bacteria.

3. Drum method
Cut the bottom out of an oil drum, or make a four sides bottomless bin using galvanized iron.
Put two logs on the ground, then make a platform out of pig wire or make a frame and attach chicken wire to it.
Stand the drum on the platform.
Plant material is added to the drum that can be used just like a garbage tin.
You will need a lid to keep in bad smells.
A plastic compost bin is a neater way of storing the composting but it may smell due to lack of oxygen.
You can use a small rake to try to turn the compost in the bin if it becomes smelly.
If you put meat scraps in the compost then the metal drum or plastic compost bin will stop animals making a mess in the garden.
Bacteria that do not like air can produce compost more slowly in pits below the ground or in bins, but the compost has a bad smell.

9.14.5 Compost inspection
Examine the heap every week to see what happens to the material in the compost heap until dark coloured, crumbly, odourless
compost is formed and the compost is ready to be put in the garden.
If they have not already planted the garden, placing the compost in the soil at the level of the plant roots is best.
Do not let compost touch the stems of plants.
1. Moisture: Below 40% moisture decomposition does not occur.
Above 60% moisture you reduce airflow and the compost heap becomes anaerobic.
The best moisture content is 55% moisture so that the compost feels damp like a squeezed sponge.
You can sprinkle the compost heap with water to give the right moisture content.
To test for this take out a handful of compost from inside the heap and squeeze it.
A few drops of water should come out.
The heap is too dry if you cannot squeeze out water and there is much greyish dust from fungus.
The heap is too wet if the compost is sloppy or soggy and has a bad smell.
2. Temperature: After 2 to 3 days the bacteria and fungi generate heat and the temperature rises to 55oC to 60oC.
Bigger heaps get hotter than smaller heaps.
If the temperature of the heap rises above 60oC the bacteria and fungi may die.
To make good compost, you must turn over the heap with a fork to mix all the materials together and let in the air.
The heap will become quite hot due to the activity of the bacteria and fungi.
Turning the compost will also kill weed seeds and insect pests.
However, the temperature can be kept lower by more turning or making smaller heaps.
3. pH: The pH of plant material is originally slightly acidic from the pH of the cell sap.
During fermentation in the compost heap the acidity increases and the pH drops.
When the compost heap becomes hot due to fermentation, ammonia is produced, the pH rises and the compost heap becomes
The conversion of ammonia to protein and buffering action of humus results in a neutral pH.
Do not add lime to the compost heap because ammonia will be lost.
4. Bacteria and fungi: At first the acid producing bacteria and fungi decompose the sugars, starches and amino acids.
Later, high temperature bacteria decompose proteins, fats and hemicelluloses.
The high temperature fungus Actinomyces can decompose cellulose to give a grey white colour from the white spores.
The high temperature in the compost heap kills weeds and parasites.
Much of the carbon is converted to carbon dioxide and is lost as gas such that the dry weight and volume of the compost heap may
reduce by about 50%.

9.14.6 Start composting for the school garden
1. The headmaster must decide on a school policy that all waste materials should be saved for the compost heaps.
2. In the kitchen, peelings and food scraps are all saved and kept separate from rubbish, e.g. tins and boxes.
A few bashed iron tins may add iron plant nutrient to the compost or be used to trap air in the compost heap.
3. No student is allowed to burn heaps of dead leaves, cut grass, or weeds.
All this material must be taken to the compost heap each day.
4. Two students are appointed to look after the compost heaps every day during school maintenance time.
5. Select a well drained area of soil fairly near the kitchen and kitchen gardens, but remember that most compost heaps smell a bit.
Dig up the soil to loosen it.
You will need a shelter with a roof of leaves that will protect the compost from the sun and heavy rain but allow some water to drip
You may need to put up a fence to keep animals away.

1. Take the class to the compost heaps.
Ask the students what are the advantages and disadvantages of composting.
Ask the students what do you put on the compost heap and what do you do not put on the compost heap.
2. Show the students 3 compost heaps:
Heap 1. New material is still being added.
Heap 2. The material has packed down and it is time for turning it.
Heap 3. The compost is dark coloured, crumbly and ready to be put in the garden.
3. Let the students put their hands in each heap, take out a handful, squeeze it and smell it.
Ask them to describe what they see, feel and smell.
4. Tell the students what happens if compost is too wet or too dry.
Ask them whether the compost they touched was too wet or too dry.
5. Demonstrate how to do the 3 composting jobs then let the students do them.
The first composting job is to place layers of material on the heap until it is about 1 metre high and keep the heap damp.
The second composting job is to turn the compost to let the air get in and keep the heap damp.
The third composting job is to dig out the compost and dig it into the soil.

9.14.7 Worm farms
See: Composting websites
1. A worm farm minimizes food waste by turning organic kitchen waste into liquid fertilizer and worm castings, the organic material
that has been digested by the worms.
After about two months rich, dark worm castings will be building up and worm juice will start to accumulate at the bottom of the
worm farm.
Worm castings, called vermicast, and compost are the best soil conditioners.
Castings should be dug into recently watered soil, or watered in when added.
If added in spring or summer, the area should be mulched straight after adding the castings.
They can be added to any area of the garden, including vegetable beds.
The worm castings fertilize the soil to encourage strong plant growth and healthier soil.
A generous handful of worm castings added to a watering can, stirred, and used straight away makes a great compost to be applied
to the vegetable and favourite plants.
Worm juice, worm farm liquid, is the liquid that drains out of the worm farm and is said to be the richest liquid fertilizer known.
It is also worth collecting and spreading around the garden, although it is not as rich as the castings themselves.
When using worm juice, it is best to dilute it at least ten parts water to one part worm juice until it is the colour of weak tea.

2. Worms do not like the heat or direct sun so choose a cool shady spot inside or outside.
Worms like temperatures from 15oC to 25oC, so place the worm farm in a cool environment protected from hot sunlight and rain.
A worm farm should be double insulated to help in maintaining an even temperature.
Purchase a worm farm or make the worm farm out of recycled plastic, polystyrene vegetable boxes or wood, but treated wood can
leach chemicals.
To prepare the worm farm for worms, the worms will need a bed inside their box.
It should be made out of good quality soil, leaves and shredded paper.
The worm bed should be around 15 cm deep.
Add a little water to the worm bed because it needs to be kept moist but not wet.
Remember to make sure the worms have enough bedding and that you keep the worm farm damp, covered and cool.
If you notice pests like slugs and vinegar flies once the farm is up and running, dust the top with lime and check you have not added
too much food.

3. Get the worms from commercial worm growers or the local nursery.
The common types are: Tiger, Indian Blue and Red Wriggle.
Worms are usually available by the thousand and you'll need between 1, 000 and 2, 000 worms to start with.
They will multiply over time.
Settle the worms in by gently spreading them over the surface and watch them burrow into their new bed.

4. Feed the worms
Worms do not have teeth.
The worm has an organ called a prostomium used for prying food apart.
They have mouths that slurp down food, a gizzard like a chicken that grinds the food and an intestine.
Worms are better able to eat food that has been cut into smaller pieces or liquidized.
Worms enjoy a variety of food and can eat their own body weight each day.
Only feed your worms when all of the previous food has been consumed.
Any left-overs will turn anaerobic causing bad odours, souring your soil and killing your worms as there is no oxygen for them to breathe.
Slowly increase the food as the population of your worm farm increases.
It is better to underfeed your worms than over-feed them.
Before feeding, fluff up the top 5 - 10 cm of soil with your gloved hands to allow air flow, prevent compaction and reduce odours.
Feed the worm farm every seven to ten days or when the previous food has been consumed.
Worms can consume kitchen greens, vegetable peelings, horse or cow manure, tea bags and coffee grounds
(with staples and tags removed from tea bags), crushed eggshells, small amounts of moistened and shredded paper,
and cardboard, e.g. shredded egg cartons, and the contents of vacuum cleaner dust bags, .
Chop up their food as small as possible so the worms will get through it faster.
Add the kitchen waste regularly in small amounts and in one place at a time.
Cover new food with a light cover of their bedding material or a handful of soil or compost.
For hard fruits and vegetables cut into small and thin pieces.
For soft pieces of fruit cut up and place face down.
However, excessive application feeding of fruit will increase the acidity (pH level) of the worm farm due to high sugar content.
Grind egg shells and cereals.
A regular sprinkle of oatmeal helps with protein levels.
Feed the worms once a week and only when they have almost finished their last meal or it will start to rot.
Do not feed worms on dairy (butter and cheese), meat, fish, fat, bones, citrus peel, onion, garlic,
bread, shallots, potatoes, oils, salted food, pickled food, fresh grass clippings, sawdust.
Meat and dairy products attract vermin, flies and maggots.
Pineapple can kill the worms.
Worms need a pH level of between 5.5 and 7.5.
Worms do not live or breed well in acidic conditions that can be created by some fruits with a high sugar content or a diet high in fruit.
Use a simple pH soil testing kit once a month to learn and monitor the pH level in the worm farm.
Add baking soda or dolomite lime watered in to help raise the pH level and reduce acidity in the worm farm.
Dolomite lime is similar to garden lime, but contains more magnesium.
The contents of the worm farm must remain moist.
If the contents are too dry, the worms will perish.
If the contents are too wet, the worms will drown.
Most foods used in worm farm has a high moisture content.
Dry food such as paper will be soaked in water before applying.
When applying water, do it slowly and gently so it can percolate through the soil and collect valuable minerals.
A slow application will also provide least disturbance to the worms.
For a worm farm holding two litres of liquid, once a week drain and collect the liquid,
and mix it at a ratio of 1:1 with rainwater to create the liquid fertilizer.
Replace the two litres of moisture with rain water using the process outlined above in the moisture section.
For best results the harvested liquid should be used as soon as possible after harvest,
as it contains living organisms that will be beneficial to your plants.
Worm juice that is stored will lose its potency and benefits very quickly.

4. Harvest worm liquid and castings
If the worm farm captures worm liquid, empty the tray regularly using the tap.
To harvest the worm castings, move the worms' bedding to one side of the farm,
add fresh bedding to the empty side; then wait a few days.
Most of the worms will migrate over to the fresh bedding.
Then you can take out the old bedding and use it on the garden.
It is okay to transfer some worms into the garden when you empty the old bedding.
You will also be transferring worm eggs, which will hatch in the garden and improve the soil.
Use the castings to improve soil quality and for fertilizing around plants.
You can also add a sprinkle of worm castings onto pot plants.
Dilute the liquid fertilizer.
A good handful in a nine litre bucket of water stirred really well can then be watered onto the plants.
If you have a backyard, build a compost heap or bin to make use of the remainder of the food scraps as well as the garden waste.
This means that they cannot generate their own body heat.
A worm farm is easier to work with if it is at waist height.
Empty the contents of your worm farm onto wet newspaper in full sunlight.
The worms will quickly burrow down to the newspaper to avoid the sun/warmth.
Wait approximately two minutes for this to take place and then start to scoop off the layers slowly,
so work towards the base leaving a thin layer for the worms to remain in.
Place the harvested soil into a buck and cover with a moist towel to stop it from drying out.
Castings should be used soon because they contain living organisms that will be beneficial to your plants.
Remove 50 per cent of the worm population and replace the polystyrene bits on the bottom,
and cover with approximately five centimetres of gravel and sand.
Prepare a mixture of mainly manure, vermiculite and palagonite and fill the container up to within 5 centimetres below the air holes.

5. Worm problems
If you are going on holidays, worms can survive for 3 to 4 weeks.
Oatmeal will last longer than any other food and will not affect the pH level.
If a worm farm is too wet, remove three handfuls of soil (minus the worms),
and replace with three handfuls of vermiculite and cow manure.
If the worm farm is smelling, check the pH level.
Overfeedinq is a common cause of bad smell, so remove uneaten food and add some soil and potting mix.
If the worms are trying to escape the worm farm, check the pH level, check for overfeeding, and check for exposure to heavy rain.
If ants invade the worm farm it may be may be too dry, so add water.
Also, to control ants, raise the worm farm off the ground and smear Vaseline on the base.
If flies, maggots, and cockroaches enter the worm farm, they are attracted to rotting food,
so do not overfeeding and ensure that all food is consumed and that the worm farm is not too wet.

Before teaching this project, discuss the content of the lessons with a field officer of the Ministry of Agriculture, and get advice on
planting material, planting distances, site for planting, approved mulch, composting, and control of pests and diseases.
Use only the procedures, agricultural chemicals and insecticides recommended by the local field officer of the Ministry of Agriculture.