School Science Lessons
School food gardens for tropical regions
2013-05-15
Please send comments to: J.Elfick@uq.edu.au
Preface
Table of contents
9.100 Abscisic acid, C15H20O4, plant hormone
9.14.0 Composting
9.12.0 Crop care
9.13.0 Mulching
9.8.0 Planting crops
9.9.0 Seeds
9.10.0 Vegetative reproduction
9.14.0 Composting
Composting, "Tumbleweed", worm farms
Composting, Wormfarming, Australian city councils
9.14.0 Composting
9.14.3 Carbon / nitrogen 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
9.12.0 Crop care
Crops and farming
9.12.0 Crop care
9.12.8 Harvesting
9.12.4 Hoeing
9.12.7 Plant protection
9.12.6 Staking
9.12.2 Thinning and roguing
9.12.3 Top dressing and side dressing
9.12.5 Watering
5.17 Weed control
9.12.1 Weeding
Weeds, Weeds in Australia
Weed Gunnel, weed blocking fabric, Australia, (commercial website)
9.13.0 Mulching
9.13.0 Mulching
6.36 Mulch saves water
5.38 Mulch garden soil (Primary)
9.8.0 Planting crops
9.8.0 Planting crops
9.8.6 Companion planting
9.8.2 Grow you own seed
9.8.1 Imported seed
9.8.5 Interplanting
9.8.4 Pot plants
9.98 Potting mix experiment
9.8.3 Four methods of planting
9.9.0 Seeds
9.9.0 Seeds
9.9.2 Depth of Sowing
9.9.1 Germination test
5.14 Seed, Parts of a bean seed
5.15 Seed germination
9.10.0 Vegetative reproduction
9.10.0 Vegetative reproduction
9.1.7.0 Auxins, plant growth substances
9.10.1 Cuttings
9.10.2 Division
9.10.6 Grafting
4.3.0 In vitro culture techniques
9.10.3 Stooling
9.10.4 Layering
9.10.5 Marcotting, air layering
5.16 Planting material
9.97 Roots from plant parts
9.8.3 Four methods of planting
1.0 Direct planting of seeds and cuttings into the field
2.0 Planting in a seed bed of fine even soil sheltered by a roof. Later chose the best plants for transplanting
3.0 Planting in seed boxes sheltered by a roof
4.0 Planting in a plant nursery
4.3.0 In vitro culture techniques
4.3.1 Grow African violets with in vitro culture
4.3.2 Grow African violet from pieces of leaf
4.3.3 Grow gerbera using in vitro culture
9.10.6 Grafting
9.10.6 Grafting
9.93 Bud grafting, orange, rose, fruit trees, apple, pear, plum
9.94 Shoot grafting, citrus
9.95 Whip and tongue grafting, fruit and ornamental trees
9.10.1 Cuttings
9.10.1 Cuttings
9.1.7 Auxins, growth substances
9.88.1 Ethephon
9.89 Commercial rooting powders for stem cuttings
9.90 Leaf cuttings
9.91 Root cuttings, phlox, hollyhocks, wild cherry
9.92 Stem cuttings, top cuttings, geranium, poppy, fuchsia, chrysanthemum, blackcurrant
6.36 Mulch saves water
1. You can save soil water in two ways: 1.1 Cut down weeds and bushes that grow near your coconuts, breadfruit, vegetables or bananas. Then the roots of these plants cannot steal the soil water. 1.2 Cover the surface of the soil around your plants with a layer of dead leaves, grass or other material. This layer is called a mulch. The mulch stops the hot sun from making the soil surface dry.
2. Weeds and bushes take soil water from the coconuts, breadfruit and other useful plants. Cut down but do not burn these weeds because you can use them for mulch.
3. Mulch keeps the soil moist around plants. Mulch is any light, loose covering on the soil. Old dead grass, coconut leaves and breadfruit leaves make good mulch.
4. Some ways to save soil water: 4.1 Cut down weeds that steal soil water from trees. 4.2 Put a mulch of dead leaves around young trees or vegetables. 4.3 Make mulch. Gather dead leaves or grass and make a mulch around some young tree such as a coconut seedling or a young breadfruit. The next week, lift up the mulch to see that the soil under it is cool and moist.
9.8.0 Planting crops
See diagram: 4.0: Sterilizing the soil | See diagram 61: Sweet potato planting, planting material
See diagram 4.0: Seed beds and seed boxes
These lessons are designed to make the students think about the advantages of using a seed bed. Sow some plants directly into a garden. They are not raised in a seed bed and then transplanted, e.g. bean, peas, carrots, cucumbers, melons, and pumpkins. Use a seed bed for plants like tomato, onions, lettuce, because you must have good seedlings if you want to make the best use of small areas of gardens. Planting material includes stem cuttings, rhizomes, tubers, corms, and seeds. Only seeds can be imported from other countries. They must be in sealed silver packets and have the scientific name of the plant written on the outside package.
9.8.1 Imported seed
Advantages
1.1 They are free from diseases and insect pests. 1.2 All the plants grown from the seed in a packet will be the same. 1.3 The seed has been chosen to give a high yield.
Calculate exactly how much seed is needed and buy the number of packets.
Disadvantages
1.4 Imported seed is expensive. 1.5 There are many different varieties and it is hard to know which to choose.
1.6 You cannot use hybrid seed such as corn and cabbages to produce seed for another crop so you
need new hybrid seed for each crop.
1.7 Imported seed may not be suitable for the tropical conditions.
9.8.2 Grow you own seed
Advantages
2.1 The cost of producing your own seed is less than imported seed.
2.2 Seeds that are chosen from the best plants in your garden should be suitable for the conditions in your
garden.
Disadvantages
2.3 The plants produced may vary a lot due to genetic variation.
2.4 The seed may carry disease or insect pests if not treated with pesticide.
2.5 Seed may die if it not stored in cool dry conditions.
2.6 There may not be enough seed for your needs.
9.8.3 The four methods of planting
1.0 Direct planting of seeds and cuttings into the field
The soil should be prepared and fertilized 2 weeks before planting. Planting must be done at the correct depth and correct spacing. The seeds must look fat and healthy. Plant them in furrows or holes, singly or plant 2 seeds per hole and destroy the smaller seedling. You may plant cuttings singly but there are many different methods.
Advantages
1.1 It is a cheap and simple method, 1.2 There is no damage due to transplanting, 1.3 Plants are easy to look after. Surviving plants may be stronger, 1.4 Some seeds must be sown this way. e.g. bean
Disadvantages
1.5 Less seed germinates so there are fewer baby plants, 1.6 You have less control over what is grown in the field
2.0 Planting in a seed bed of fine even soil sheltered by a roof. Later chose the best plants for transplanting
Use a seed bed of specially mixed soil sheltered by a leaf roof. The soil is a mixture of 2 buckets of sieved good soil and 1 bucket of washed river sand and 1 bucket of rotten compost. Sterilize the mixture to kill weed seeds, pests and diseases, by heating in a drum oven. Seedlings may need thinning out and the plants should be hardened by not watering and by gradually removing the roof a few weeks before transplanting. Select the strongest plants for transplanting on a dull afternoon and water the transplants well.
Plant seeds and other planting material as follows
2.a Long deep grooves in the raised bed or field (furrows). Use a hoe to make them. 2.b Short shallow grooves in the seed bed called drills. Use a rake handle to make them. 2.c Hills or mounds to allow all round drainage for sweet potato, corn and pumpkin
Advantages of planting in a seed bed: 2.1 More seeds germinate and more baby plants live. 2.2 It saves time because other plants can be growing in the field while baby plants are in the seed beds. 2.3 You have more control over what is grown in the gardens.
Disadvantages of planting in a seed bed: 2.4 It is an expensive and complicated method, 2.5 It wastes time. 2.6 Transplanting may damage roots. 2.7 You must water the plants every day. 2.8. Skill is needed to look after baby plants properly!
3.0 Planting in seed boxes sheltered by a roof
1. Use boxes that are about 24 cm × 24 cm × 15 cm and are kept on shelves in greenhouses with a roof of sticks or leaves or artificial shade such as "Sarlon". Sterilize the soil in the seed box before planting the seeds. Plant them in regularly spaced holes. You can mix very tiny seeds with dry sand before sowing to make them easier to handle. The sand spaces the seeds well. Another way is that you may sprinkle small seeds along a shallow drill and when the cotyledons have just opened you transplant the seedlings into a second box with regularly spaced holes in the soil (pricking out). Sterilize the seed boxes and soil in them to kill pests and diseases. You can take the seed boxes to the field when transplanting. Make seed boxes with wood or tin plate, e.g. kerosene tins. However, you must make sure that air can get into the soil and that the soil is well drained, otherwise the roots will not grow well.
2. To propagate plants from seeds, buy special seed raising mixtures or use the same potting mix for seeds as you do in the pots. Fill the trays with potting mix, smooth off the top, and water with a fine nozzle. Put a small indentation with your finger in each cell. Sprinkle in seeds. Fine seeds you may put up to six in each cell. For big seeds, put two in each cell. Cover with perlite to give a light weight cover for the seeds to push through, and providing moisture retention. The smaller the seed the thinner the cover, larger seeds should be covered by the same depth as they are in diameter. Cover the seedling trays with plastic to provide high humidity and to avoid moisture loss. Keep the seeding trays moist. When the true leaves have emerged, you will need to fertilize. When the seedlings are ready to pot up, or plant in the ground, place the trays in the sun for three to five days, to harden the top growth and increase the strength of the root system.
4.0 Planting in a plant nursery
Use a plant nursery for the three following reasons:
1. Give seeds and young plants the best conditions for germination and rapid growth.
2. Use the land for other purposes while the plants are in the nursery.
3. Prepare the land for planting right up to the time of transplanting.
4.1 Site of a plant nursery
Choose the site of the nursery carefully. It should have a constant water supply and not be flooded. The land should be flat and sheltered from strong winds. The soil should be well drained, with a pH between 6 and 7, cleared of tree roots and weeds and be deeply cultivated to produce a plot to be shaded by trees or buildings anytime of the day.
4.2 Protection from wind for a plant nursery
Plants in the nursery must be protected from: strong winds, the hot sun in the middle of the day, and raindrop damage. The best protection from strong winds is a brush fence 3 metres high but for the long term it is better to plant windbreaks using trees such as Leucaena. In most places build walls and a door that you can lock to keep out animals.
4.3 Shade for a plant nursery
A shade roof 2 metres above the ground supported by posts 3 metres apart can protect plants from the hot sun and heavy rain. The roofing material that is the easiest to collect and put on the roof are coconut palm leaves. However, this material has the disadvantages that the shade is uneven and blocks out too much sun in patches also light rain may run off the roof and not get to the plants at all. The best roofing material is lots of sticks or bamboo about 5 cm in diameter that you can be arrange to provide an even
shade and let some light and rain pass through. Having lots of small spaces in shade is best. It is possible to import shade made of plastic called "Sarlon" but it is expensive and may not last many years in the hot tropical sun. Two weeks before transplanting the plants should be hardened by gradually removing the shade so that you only transplant those plants that can grow well in the hot sun.
4.4 Seed beds in a plant nursery
Plants can be grown in the seed bed or in seed boxes or other containers. The advantage of using the seed bed is that it does not take much preparation or looking after. The disadvantage is that you may damage the plant roots when transplanting. The advantage of using seed boxes or containers is that you have more control over the plants and you can select the best plants for transplanting. The disadvantages are the costs of containers and benches, the plants must be looked after more, e.g., you must water them every day and sometimes the plant roots do not grow properly in the containers. Using seed boxes and containers in a plant nursery is always worthwhile provided you prepare the students and look after them properly.
4.5 Soil mixtures for a plant nursery
There are many ways to make up a soil mix. One mix could be: 2 buckets of sieved black topsoil, 1 bucket of river sand, 1 bucket of old sawdust or crushed dried leaves, 1 drink can of NPK fertilizer 4% N, 6% P, 4% K + trace elements. This should contain sulfur. If the pH is less than 6, add lime. The soil mixture used in the seed beds must be light and crumbly. It should allow air to get in, hold water and let the extra water out easily. If the soil mixture packs down in the seed box or container the plant roots will not grow well, provide the right amounts of plant nutrients, be free from pests and diseases.
4.6 Sterilizing the soil for a plant nursery
Cook the soil mixture to kill disease and weeds. You must cook the soil mixture over a fire for a couple of hours to kill off all the disease and weed seeds. Cut the top out of an oil drum. Make many small holes in it. Make holes through the drum 30 cm above the bottom, and put iron bars through the drum. Put the lid inside the drum so it rests on the iron bars.
4.7 How to sterilize the soil
See diagram 6.0.1: Sterilizing soil
1. Put water in the bottom of the drum.
2. Put soil in the top part of the drum.
3. Make the soil slightly wet.
4. Put a sweet potato in the soil near the top, put a cover on the drum.
5. Light a fire underneath the drum to boil the water and "cook" the soil.
6. After about 2 hours of cooking, check to see if the sweet potato is cooked. If it is cooked, then the soil is ready. You can use the seed box mixture again, but you must sterilize it each time before you use it. If any of the plants in the seed box get a disease, then you must also sterilize the box before you use it again. Put in boiling water for 15 minutes.
9.8.4 Pot plants
Planting in a container should be the ideal way to create optimum conditions for plant growth. However, some plants have very specific requirements and some plants should never be grown in pots. For example citrus grows well in pots but a tuberous begonia does not. Before using pots check which plants that grow well in pots in your area. Overwatering is a common cause of pot plant death, especially kitchen herbs, so group pot plants together according to their watering needs. A drip irrigation system makes watering easier. Pots made of terracotta or stone make take water away from plants so use a coat of sealant to make them less porous. Maintain constant applications of fertilizer because the pot plant has little surrounding soil compared to the plant growing in the ground. Some pot plants have very specific fertilizer needs. Seasol and fish oils are useful soil conditioners for pot plants.
1. Dig a hole 4 × width and 2 × depth of the pot. Loosen the soil at the sides of the planting hole. Fill the hole with water and allow it to drain away. Add wetting agent to half of the soil taken out and to be used as backfill. Remove the plant from the pot by inverting the pot and tapping it until the plant with root ball emerges. Place the plant in the hole with the top of the root ball level with the surrounding soil surface. Fill the remaining hole with backfill. Press the backfill down to leave a saucer-shaped depression around
the plant. Water the plant after planting and then water it once a week for two months with the volume of water equal to twice the volume of the original pot. Then water only when the soil feels dry. Add some coarse mulch in a 50 cm radius but not touching the stem of the plant. The applied mulch should contain composted animal manure and leaf litter. Do not put fertilizers or new animal manure in the bottom of the planting hole because they may burn the plant roots. Prune off broken branches from the new transplants.
2. Clay pots and plastic pots are tapered, i.e. they are wider at the top than at the bottom. The taper makes it easy to get the plant and soil out without damaging the roots when you hit the upside down pot sharply. However, clay pots are expensive, heavy and break easily if dropped or trodden on.
3. Use iron fish tins, drink tins and aluminium drink-cans for containers. However, they are not tapered so cut the side of the tin with tin snips to get the plant and soil out. Punch holes in the bottom and sides of these tins and drink-cans from the inside out. These containers are so cheap and plentiful so it is a good idea to experiment with them. Collect aluminium or tin plate beer cans, half fill with soil mixture and use one for each seed
4. Make basket pots by winding banana leaves around a log then taking the log away. Also, you can cut bamboo to make pots but you may have to split them to get the plant and soil out.
5. Buy special pots made of compressed peat, e.g. "Jiffy Seven" pots. They are excellent for transplanting single plants but they do not stand up for long before collapsing and they are expensive. Stand them in a shallow tray to take up water then you can transplant without damaging the plants.
6. Use black plastic polythene bags called polybags for plants that must be left in a nursery for a long time, e.g. coconuts. Polybags may get very hot if left in the sun and this can damage the roots. They may come in the form of sleeves to provide extra drainage.
9.8.5 Interplanting
Interplanting is used when you grow different kinds of plants in different rows in the same garden. One advantage of interplanting is that it allows you to grow more food without increasing the size of your garden. You do this by growing small plants with short growing periods such as radish, okra, lettuce, dwarf bean and spinach between rows of large plants with longer growing periods such as tomato, cabbage, capsicum and eggplant. Many food crops such as peanut, corn, pineapples, banana and ginger can be grown between coconuts and you can interplant papayas or banana with pineapples. The general rule in school food gardening is to grow your plants as close together as you can without the plants becoming stunted and always to have a mixture of plants in your gardens, e.g., if you plant corn on ridges in the fields, also plant bean between the ridges. Try some trials comparing single crops with interplanted crops, e.g. bed 1 sweet potato, bed 2 corn, bed 3. sweet potato interplanted with corn.
Table 9.8.5 Examples of interplanting:
Row 1 Row 2 Row 3 Row 4 Row 5
Corn (Maize) Chinese Cabbage Radish Lettuce Radish
Mung Bean Tomato Spring Onion Tomato Mung Bean
Lettuce Tomato Lettuce Tomato Lettuce
Cucumber Corn (Maize) Cucumber Corn (Maize) Cucumber
Advantages of interplanting: 4.1 you can grow more food in the garden, 4.2 some plants can help others by protecting the students against pests and disease, 4.3 pests and disease cannot move between the same kinds of plants, 4.4 weeds are controlled by shading.
Find local examples of interplanting in village gardens. Ask gardeners why they grow different kinds of plants together.
9.8.6 Companion planting
Another advantage of interplanting is that some plants have plant friends which can protect the plants from pests and help them to grow better. Marigolds planted in a border around a garden bed can protect plants of the tomato family from nematode worms. Also marigolds can keep beetles away from beans. Velvet bean can protect tomato from nematode worms.
Table 9.8.6 Examples of plants and their friends
Plant Friends of this plant
bean maize (corn) cabbage, cucumber, lettuce
eggplant (aubergine) bean
pumpkin maize (corn) sweet potato
taro spring onion
Use companion planting to control pests and diseases because it is difficult for pests and diseases to move between the same kinds of plants if they are separated by other kinds of plants. Interplanting also helps control weeds by shading.
9.9.0 Seeds
See websites: Seeds
See diagram 9.113.2d: Seeds planted at different levels
Description of type of plant
Common name and scientific name
Annual life cycle: 4 to 12 months, Biennial life cycle: up to 20 months
Hardy, survives frost / cool soil
Sow in soil at +10oC to + 20oC
Position: Full sun, part sun part shade, full shade
Months to flower, Months to harvest
Watering: Thirsty plant, seasonal watering, drought tolerant
Height and width of mature plant / flowers
Fungicide protection: Chemically treated / untreated
Sow: Direct / transplant
Best use by date
Germination %
Seed count in packet
Price
Packing reference number or lot number
Address of supplier
1. Choose seed from a group of plants which all have the characters you are looking for, e.g. large fruit or resistance to pests and disease. There is then a good chance that the plants produced from this seed will have the same characters as the parent plants.
2. Other planting material such as stem cuttings should be chosen from the best plants in the crop and must be free of pests and disease. The best time to harvest seed is when the fruits are fully ripe but you may have to protect the fruit from birds and insects with paper or plastic bags.
3. Seed should be dried in the shade and any juicy material picked off. The seed must be clean of leaves, stalks and dust. Put the dry seed in a jar, shake with copper oxychloride fungicide and then keep in a cool place. Do not let students breathe in the fungicide dust or eat the seeds because all fungicides are poisonous. Plant most tropical seeds soon after harvest.
4. When seeds remain alive and can germinate to form baby plants you say the seeds are viable. Test the viability of seed before planting. Otherwise, you waste time and effort on useless seed. To test the viability of small seeds, soak 20 seeds for an hour then put the seeds on wet newspaper in a closed container. After a few days count the number of seeds which produce healthy roots.
Percentage germination = (No. germinated seeds / No. seeds planted) × 100
5. With large seeds it is best to plant 20 seeds in a container in the nursery. If fungus attacks the germinating seeds, shake the seed with copper oxychloride fungicides and do the test again. Some seeds with very hard seed coats such as Acacia should be dropped in boiling water before sowing. Most larger seeds germinate more quickly if soaked for 1-2 hours first.
6. The depth of sowing is usually printed on the packets of imported seed. For your own seed the best rule is to sow the seed at a depth of at least 2 cm, or at a depth of 3 times the width of the seed (but not more than 8 cm). You can set up some interesting trials comparing the germination of seeds soaked and unsoaked, and at different depths in the soil. If you sow seeds at too shallow a depth they may be uncovered by the wind, eaten by birds or rats, or the roots will not grow properly. If you sow seeds too deeply, the plant may become exhausted and be unable to push the cotyledons above the soil. Sometimes students will dig up sown seed of plants such as peanut and eat them. This is a problem of student discipline but it can be quite dangerous if the seeds have been treated with fungicide. If you are direct planting, always dig the soil one month before planting seeds. About 2 weeks before planting dig in rotted compost, wood ashes and fertilizer which should have a high content of phosphate, e.g. NPK 4%, 6%, 4%. Phosphate makes roots grow well.
7. You can drop very small seeds into the furrow fairly close together then pull out the weaker plants to leave the stronger plants growing at the approximate recommended spacing. This method is called thinning out. Also you can plant a group of seeds in shallow holes at the correct distance and when the plants are 3 cm high destroy all plants except the biggest ones. The advantages of sowing seeds directly into the soil are that it saves time and does not damage the roots during transplanting.
9.9.1 Germination Test
See diagram 9.3.49: Germination test
1. Give 20 seeds to each group of 4 students.
2. Show the students how to soak the seeds first.
3. Then tell the students how to do the germination test: you can use half coconut shells for containers.
4. After 4 or 5 days students count the number of germinated seeds and work out the germination percentage.
9.9.2 Depth of Sowing.
The two dangers for a seed
1. The seed may dry out. Then it may not germinate because it has no water. You can stop this danger by covering the soil very lightly with some powdered animal manure or leaf mould. It also helps if you mix some sand with the topsoil because this sand will keep the soil open and let rain in.
2. The other danger is that seed may get too wet and be attacked by a fungus called the "damping off" fungus. You can stop this fungus by putting sand in the topsoil. This sand will let a lot of rain drain away quickly.
9.10.0 Vegetative reproduction
See diagram 9.93.2: Vegetative reproduction
Make more plants by taking pieces of a plant and using the students to grow new whole plants. This is called vegetative reproduction. The advantages of using vegetative reproduction is that the piece of the plant usually grows easily and the new adult plants produced will all have exactly the same characters as the parent plant.
9.10.1 Cuttings
See diagram 9.93.1: Cuttings
1. A cutting may be a piece of root, stem, leaf or bud. A root cutting must be able to produce a shoot and a stem cutting must be able to produce roots, usually from a node. Cuttings must get enough water and air so that they can produce roots and shoots. New roots and shoots can come from buds at the nodes. If a cutting is half buried in sand, roots will grow from the lower part and shoots from the part above ground. Do not mix compost or leaf mould with soil used for cuttings but use clean sand. After the cuttings have rooted, they can be moved to a richer soil with leaf mould in it.
2. To propagate plants from cuttings, fill trays with potting mix, smooth off top, and water. Collect cutting material from healthy plants. Use sharp clean secateurs and cut below a node. For small-leaved plants remove lower leaves from cutting.
Larger-leaved plants may also require some remaining leaf area to be reduced. Make a hole in potting mix (use a stick not much bigger than the cutting) and place in prepared cuttings. Gently press around cutting. When all cuttings have been done, water in well. This will ensure that cuttings are in contact with potting mix. Trays of cuttings are then placed in an igloo or other humid environment. Keep moist. Once cuttings have roots you will need to fertilize them.
3. The best cuttings medium is 1 : 4 peat : perlite.
9.10.2 Division
See diagram 9.81: Bulb | See diagram 9.82: Corm | See diagram 9.83: Rhizome
1. Pull apart the diffuse plants with many shoots or offsets. Adult cells of plant organs may revert to meristematic activity and reveal their original embryonic characters. Division is a natural process when a plant forms new plants as offshoots, e.g. bulbs, corms, rhizomes. Parts of the plant grow to form new plants and later separate from the mother, e.g. Michaelmas daisy, delphinium, suckers of raspberry canes. Division can also refer to the separation of side shoots from a bulb as in spring onion or separating the suckers which grow up from the banana corm or breaking a ginger rhizome into pieces.
2. To propagate plants by division, turn pot upside down squeeze and shake plant out. Remove as much potting mix as possible. Pull plant apart into sections, depending on whether you want to produce a few well established plants or many smaller plants. Use a knife or secateurs to divide plants with large roots or rhizomes. Matted pot bound roots can be cut. Trim long roots to a depth of half a pot. Half fill pots with potting mix. Hold newly divided plant in the pot and fill with potting mix. Water in well, then water in with a liquid seaweed-based fertilizer, to prevent transplant shock.
9.10.3 Stooling
See diagram 51.13.1: Banana stool
The plant is cut down to ground level where it forms lots of new shoots each shoot then produces its own roots. These rooted shoots can be cut off and planted separately. Stooling can be used on guavas.
9.10.4 Layering, carnation, rubber plant, lilac, rhododendron, rose, clematis, blackberry
See diagram 9.93.2: Layering
The plant is bent down until a branch touches the ground then secured using pegs or wire hoops. New shoots and roots then form from each node, then by cutting between each node new plants are formed. Layering can be used on mango. Bend a branch down over the soil and fix pegs so that some nodes are below the surface. Adventitious roots grow from the buried nodes. The axillary bud near the peg grows upwards into an aerial shoot. Cut the layered stem from the parent plant and let it grow independently. For air layering of the rubber plant, make a longitudinal cut below a node almost to the centre of the stem. Treat the cut with plant cutting
powder then bind on moist cotton wool covered with polythene film. Roots form in the layering.
9.10.5 Marcotting, air layering
See diagram 9.93.3: Marcotting, 1. Remove strip of bark 1-2 cm wide, scrape to remove any remaining bark or cambium tissue. 2. Cover girdle with moist sphagnum moss. 3. Wrap with polyethylene film. Wrap and tie ends with polyethylene tape or electrician's tape.
In marcotting, (marcottage), a cut is made below a joint or node and covered with a moss into which new roots grow.
1. Propagation by air layering or marcottage, by Paul Moore, Indoor Citrus and Rare Fruit Society
Air layering is a method of propagating several kinds of evergreen, broad-leaved, tropical and subtropical fruit trees. The Chinese have used this technique, which they call "gootee," extensively for more than 1,000 years to propagate the lychee, a species difficult to propagate by other asexual methods. Air layering, also known as "marcottage", is the preferred method of propagating guava, lychee, longan and the ornamental Ficus elastica. Other fruits and nuts that can be propagated as marcots are acerola (Barbados cherry), carob, carambola, cashew, citron (Citrus medica), fig, lime, lemon, pomelo, loquat, macadamia and mango. Other methods such as budding, grafting, and cuttings are generally preferred over marcottage because they are easier, less time consuming and more economical of propagating material. Also, these alternate methods can be more successful in non-humid regions. Air layering is more reliable in outdoor climates that remain humid and rainy during the rooting period, and in greenhouse environments. The most limiting factor in marcottage is keeping the rooting medium continuously moist. Periodic rewetting will be required if it dries.
The air layer is started by selecting mature branch tips that developed in the previous growing season. Spring is the best time of year. The selected terminals are girdled by removing a ring of bark 1 to 2 cm wide and about 12 to 15 cm below the tip. Scrape the remaining inner bark tissue thoroughly, removing it down to the wood. The purpose of this step is to prevent the girdle from healing and to induce rooting above the cut. Treating the exposed cut and the bark above the girdle with a rooting hormone preparation, e.g. IBA, indolebutyric acid, 8000 ppm or 16000 ppm.
Place a large double handful of moist, but  not wet, sphagnum moss about the girdled surfaces and the intact bark above the cut, and then wrap with polyethylene film. Tie the upper and lower ends tightly around the stem. Rewetting the sphagnum may be necessary if it dries during the rooting process. Leave the marcot on the mother tree until the roots are visible through the plastic film. This may take from two to six months. After adequate rooting occurs, sever the marcot, unwrap and transplant it into a container. Survival is improved if the air layer is kept in a humid greenhouse or a cool, shaded site until well-established. Since there is an imbalance between root and top, is is also recommended to prune back the top when it is potted. Normally marcots are not planted into the open ground until the spring following potting, or until they are well-rooted and established in their containers.
2. Marcotting means wrapping bags of damp soil or other material around a stem so that roots will grow out of it. Later the stem can be cut into lengths with roots growing out of the lower end. It is a way of multiplying some plants that are hard to strike (start to grow) as cuttings. Cut out a complete ring of bark from a stem, and then use a cloth to bind damp earth, sawdust, or plant material around the cut stem. Sometimes it helps to paint the cut with a substance which causes growth such as indole acetic acid, but this is not essential. Roots will grow from the cuts and so new plants can be formed by cutting between the cut rings. This can be used on woody plants such as mango, avocado and cashew. Choose some plant such as hibiscus, cordyline or fig. Ring bark it at several places up the stem. Use a sharp knife and cut a shallow "V" right around it. Get some husk fibre from a coconut and soak it in water. Cut it into pieces. Wrap a handful of wet fibre around each cut made in the stem and hold it in place with a piece of rag and string. If possible wrap a piece of silver paper around the bundle. This reflects the sun and stops it getting too hot.
3. Marcotting or air layering means to cut out a complete ring of bark from a stem, and then use a cloth to bind damp Earth, sawdust or plant material around the cut stem. Sometimes it helps to paint the cut with a substance which causes growth such as indole acetic acid, but this is not essential. Roots will grow from the cuts and so new plants can be formed by cutting between the cut rings. This can be used on woody plants such as mango, avocado and cashew.
9.10.6 Grafting
See diagram 9.93.2: Budding and grafting
1. This means to make part of one plant, the scion, grow on another whole plant, the stock or rootstock. This is done when other forms of vegetative reproduction do not work and when you want to combine the characters of two plants with different characters. For example, if one kind of plant produces good fruit but its roots are easily attacked by pests and disease and if a second plant produces small fruit but its roots arc not attacked by pests and disease, then if you could graft branches of the first kind of plant
onto the stem of the second kind of plant you would have a tree which produces good fruit and which has roots not attacked by pests and disease. For grafting you need a sharp knife, a saw for large trees and tying material such as string, tape.
2. Grafting is difficult to do and usually can be done only by people who have studied horticulture in an agriculture college. Grafting means to make part of one plant grow on another whole plant. This is done when other forms of vegetative reproduction do not work and when you want to combine the characters of two plants with different characters.
9.12.0 Crop care
Think about the different jobs to do in the garden to look after the crops. Write 2 column headings on the chalkboard: Garden jobs and Reasons. Remember a different job or a reason for doing the job and write all these on the chalkboard. Other jobs that were done to look after the crops e.g. mending gates and fences, scaring birds, catching pigs, digging or clearing drains, hand pollinating flowers, burning fire breaks. Whenever these jobs are done make a note in your School Food Gardens Diary of the date, type of job
done, where it was done, time taken and number of students
9.12.1 Weeding
Weeds compete with crops for sunlight, plant nutrients, and water. Weeds make the crop plants weaker and the harvest smaller. Weeds may have pests and diseases on them which may later infect crops. Weeds can be controlled by shading, weeding by hand and hoeing and spraying with weedicide. There are different weedicide for big leaf weeds and grass-like weeds.
5.17 Weed control
Make a collection of weeds such as nut grass, sensitive plant, purslane, guava, rattle pod, pig "grass",
lantana, broomweed, water hyacinth.
Show the students examples of weeds you have collected. How do weeds harm the crops?
Weeds are plants that lower the yield of garden plants. Weeds make the garden plants grow less and
have smaller fruit.
Weeds harm crops by: taking in water from the soil, then the garden plants do not have enough water,
taking plant nutrients from the soil, then the garden plants do not have enough nutrients,
shading the young crop plants then the garden plants do not have enough sunlight for photosynthesis,
having pests and diseases on them, which can later infect the garden plants,
mixing with the crop and making it hard to harvest, e.g. sensitive plant growing among sweet potato.
Weeds live in vegetable gardens, plantations or pastures. Weeds may be of three types: Very strong
plants that are no use to us, e.g. lantana, common guava,
Plants that are weeds only when they grow in crops. However, they may also be used by themselves,
e.g. purslane is a common garden weed but it can be eaten as a green vegetable.
Plants from old crops are weeds because they may have pests and diseases on them, e.g. old maize
(corn) plants left over from a previous crop may carry disease.
Weeds can be controlled by the following:
1. Pulling out by hand
2. Hoeing
3. Cutting down with a bush knife
4. Shading by leaves of plants, e.g. sweet potato (kumara) or cover crops, e.g. Pueraria
5. Spraying with chemicals called herbicides, e.g. "Paraquat" for broadleaf weeds, "Dalapon"
("Dowpon") for grass weeds. Herbicides are dangerous, expensive and hard to use properly.
5.17 Weeds and their control, revision questions
What are five ways that weeds lower the yield of garden plants? [Take in their water, take in their plant
nutrients, shade them, have pests and diseases that may infect garden plants, mix with the crop]
What are five ways of controlling weeds? [Pulling out by hand, hoeing, cutting down, shading, spraying
with herbicides]
9.12.2 Thinning and roguing
Some plants with tiny seeds cannot be transplanted. They can be sown along a shallow drill and later some seedlings can be pulled out leaving seedlings 5 cm apart. This is called thinning. Pulling out diseased or weaker plants is called roguing.
9.12.3 Top dressing and side dressing
This refers to adding fertilizer or manure to a growing crop, e.g. nitrogen fertilizer for leaf crops, tomato, and hibiscus cabbage. Dig a shallow ditch with the hand or hoc around each plant, put the fertilizer in, and cover it with soil.
9.12.4 Hoeing
This is used to control young weeds and let air into the soil. Hoeing up or hilling-up means to use the hoe to pull up soil around the plant stems and cover the roots well. It is used for plants such as corn which have shallow roots and for sweet potato to cover exposed tubers and protect from weevils. The hoe should never be used so deeply as to damage the plants roots.
9.12.5 Watering
The soil around plant roots should always be damp but not wet. Test this with your finger. If the soil is dry the leaves will wilt and the plant will later die. In dry weather sandy soil in raised beds must be watered every day. Clay soils need watering only once each week. Water in the afternoon or evenings and keep the leaves dry. However, some gardeners in tropical regions do their watering only in the early mornings to keep plant foliage dry and be less easily infected by viruses and bacteria. Deep rooted plants like tomato, pumpkins and sweet potatoes should be watered every 2 weeks.
9.12.6 Staking
This means giving support, using sticks or wires, to vegetables such as tomato, winged bean, eggplant and choko. Climbing plants save space in the kitchen garden.
9.12.7 Plant protection
This refers to controlling pests and disease by: picking out by hand diseased plants or insect pests spraying with pesticides or fungicide burning diseased plants or parts of plants pulling out all plants left over from the previous crop and other weeds. This is called garden hygiene.
9.12.8 Harvesting
This must be done regularly and just before the crop is needed in the kitchen. Sweet potato can be stored for a few weeks if it is 1. not damaged when dug up 2. kept in a moist atmosphere for a few days to toughen the skin 3. stored in a cool place. After harvest work, Clear out all the crop plants and weeds left behind and put them on the compost heap. Then dig in rotten compost or manure for the next crop. You may plant a legume cover crop if the garden will not be planted for some time e.g. sunn hemp, butterfly pea, kudzu, cowpea. This will protect the soil from erosion, control weeds, and put some nitrogen plant nutrient in the soil.
9.13.0 Mulching
Mulching is a 10-15 cm thick layer of leaves, dry grass, or husks over cultivated soil. During dry periods fine textured mulch absorb water that may later be lost by evaporation and not passed on to the plants. So broad textured mulch is preferred because it allows water to percolate down to the plants. Mulch controls weeds by shading them from sunlight. It absorbs and stores rainfall and lessens evaporation from the soil. Mulching protects the soil from the splash erosion of heavy rain drops. Mulching should not touch the stems of plants if the mulch may contain pests and diseases, e.g. collar rot. Mulching must be renewed as it rots into the soil. Dry grass mulch or dry compost which is not rotten may take nitrogen plant nutrient out of the soil. You will need part of a garden bed which is covered completely with mulch and part not covered. All garden soil should be completely covered with 15 cm of coarse plant material or 3 cm of fresh grass clippings. The best mulch is chopped rotten grass or leaves. You can also use black plastic. In the spring, add mulch and use an organic soil conditioner to improve the water holding capacity of the soil. Apply a wetting agent after mulching to prevent waste of water.
Table 9.13.0 Mulching
Mulched Soil Not mulched Soil
1. cooler soil warmer soil
2. damper soil dryer soil
3. less soil erosion more soil erosion
4. darker topsoil (more organic matter) lighter topsoil (less organic matter)
5. less evaporation from the soil
 more evaporation from the soil
6. less germination of weed seeds (but may contain weed seeds) more germination of weed seeds
7. weeds easier to pull out
 weeds harder to pull out
1. Mulch is chopped grass, weeds and other plants which acts as a blanket layer over garden soil. Mulch is not mixed into the soil but as it rots it enters the soil. As the mulch slowly rots into the soil, new plant material should be added on top of the mulch. Completely cover the garden with 5 cm of mulch leaving no bare patches on the soil. The mulch should not touch the stems of crop plants because some pests and diseases may be in the mulch that could attack the plants. Mulch can act as a slow release fertilizer, provide a home for plant friendly insects and keep up to 70% more water in the soil. Feel the temperature of the bare soil and the soil under the mulch. Note any weeds on the bare soil and under the mulch.
2. The advantages of mulching garden beds are as follows:
2.1 control of weeds because the mulch stops light getting to their leaves,
2.2 stops rainfall from washing away the soil,
2.3 store water that the plant can use in the dry season,
2.4 stop loss of water from the soil into the air because the mulch is like a blanket over the garden bed,
2.5 the mulch rots slowly into the soil that improves the soil structure.
3. Disadvantages of mulching garden beds are as follows:
3.1 More work is needed to collect, cut and put plant material on the soil,
3.2 The work is often not done properly leaving bare patches,
3.3 Insect pests and disease may live in infected plants used for mulch.
3.4 Ask a field officer of the department of Agriculture whether it is safe to use mulch with food crops.
3.5 When the bottom layer of the mulch rots it may take some nitrogen plant nutrient from the soil
9.14.0 Composting
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.
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 adding animal manure, growing a green manure crop and ploughing it in, e.g. cow pea, 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" which 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. 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 a long time. 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, chicken and pig manure, urine. 2. High, deep litter, fish scraps. 3. About right, waste food, fruit and vegetable peelings, seaweed. 4. Low, cut grass, weeds, crop residues. 5. Very low, 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.
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, such as 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 alkaline. 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 such as 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 which will protect the compost from the sun and heavy rain but allow some water to drip through. 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 website: Wormfarming, Australian city councils
1. A worm farm minimises food waste by turning organic kitchen waste into liquid fertiliser and worm castings, the organic material that has been digested by the worms. After about 2 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 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 vegie beds.  The worm castings fertilise 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 ‘tea’ to be applied to the vegies and favourite plants.Worm juice is the liquid that drains out of the worm farm. It is also worth collecting and spreading around the garden, although it's not as rich as the castings themselves.  When using worm juice, it’s best to dilute it at least ten parts water to one part worm juice until it is the colour of weak tea. Worms don't like the heat or direct sun so choose a cool shady spot inside or outside. Use ready-made farm or make the farm out of recycled plastic, polystyrene vegetable boxes or wood, but treated wood can leach chemicals.
2. 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 centimetres 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 haven’t 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 Wriggler. 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 are happy on a simple diet. They like food scraps including vegetable and fruit peelings, tea leaves, crushed eggshells and bread. They also like small amounts of moistened paper and cardboard such as shredded egg cartons. 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. Only feed the worms when they have almost finished their last meal or it will start to rot. Don't feed worms on dairy (butter and cheese), meat, fish, fat or bones. They also don't like citrus peel, onion or garlic.
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's okay to transfer some worms into the garden when you empty the old bedding. You'll also be transferring worm eggs which will hatch in the garden and improve the soil. Use the castings to improve soil quality and for fertilising around plants. You can also add a sprinkle of worm castings onto pot plants. Dilute the liquid fertiliser. 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, another simple way to make fertiliser and reduce the amount of waste going to the tip.
9.88.1 Ethephon, 2-chloroethyl-dioxido-oxophosphorane, C2H6ClO3P, (a phosphonate), decomposes to ethylene and dihydrogen phosphate, plant growth regulator, used for cotton, pineapple, wheat, tobacco, coffee, kiwi fruit, tomato grape, apple, sugar cane, apparently not a danger to the environment
9.89 Commercial rooting powders for stem cuttings
1. Use commercial plant cutting powder, (rooting powder, plant striking hormones), e.g. "Root Strike", to stimulate and produce healthy roots on cuttings. The active constituents of the powder are indole acetic acid (IAA), the main auxin of most plants, or indolebutyric acid (IBA), or naphthalene acetic acid (NAA). Store the plant striking hormone in a dark cool place and do not let it contaminate streams, ponds or soil.
2. Select healthy end growth 10 mm or less in diameter after the growth period of the plant. Cut at an angle or select a "heel", where a branch joins. Cuttings leave two terminal leaves. Moisten the cut end of the cutting, dip it into the cutting powder and plant into free draining soil. Water the cuttings daily. If you plant next to the side of a glass jar, you can observe roots forming near the cut surface.
3. A cutting should be 50 mm to 150 mm long with an end growth diameter of 100 mm or less. Take three cuttings from the parent plant after the growth period, i.e. late summer or early autumn. For shrubs that flower in winter, e.g. camellias or daphnes take cuttings in midwinter. For shrubs that flower in the spring, e.g. azaleas, take cuttings in autumn. For roses, take cuttings from new growth in late autumn, early winter. Make an angled cut to take a healthy cutting from a parent branch. Remove the bottom leaves but leave three small leaves at the top of the cutting. Take cuttings in early morning or late afternoon. Immediately put in water after cutting and as soon as possible apply plant striking hormone by pushing the cutting into the bag of powdered hormone. The potting mix used for the initial root stage should be free flowing and light weight. However, free draining sandy loam can also be used.
9.90 Leaf cuttings, African violet, begonia, episcia, haya blanca, peperomia
1. For begonia, African violet, cape primrose, make cuts in the raised veins in the underside of the leaf at 5 cm intervals. press the leaf cut side down into moist potting mix and cover the edges of the leaf with potting mix to keep it flat. Some people push the cut veins down into the potting mix with staples or pieces of semi-circular wire.
2. For African violets, remove the leaf with petiole and insert the petiole into moist potting mix in indirect sunlight. New plants will form on the petiole in about 8 weeks.
3. For plants with succulent leaf blades, e.g. cathedral bells, mother-in-law's tongue, stonecrop, cut long leaves into 7 cm sections, dip into hormone rooting gel, then insert the sections into moist potting mix. For smaller leaves, just push them upright into the potting mix. Keep the potting mix moist in bright shade.
9.91 Root cuttings, phlox, hollyhocks, wild cherry
Cut horizontally at the top of the root and cut at an angle at the base of the root for easy insertion into the ground. Also, cut off the top of the plant just above the ground to form new shoots.
9.92 Stem cuttings, top cuttings, geranium, poppy, fuchsia, chrysanthemum, blackcurrant
See diagram 9.93.1: Stem cuttings | See diagram 9.93.2: Cuttings
1. Put one end of a cut stem in damp sand. Note the wound tissue, callus, that develops from which roots form. At the other end, dormant lateral buds form new shoots.
2. Cut two pieces of stem with leaves, from a geranium plant. The most suitable are short, compact shoots on which the leaves are close together. A cut is made just underneath a stalk bud. Fill two flowerpots with sandy soil to just below the rim. Plant a cutting half a finger length deep in each pot. Press the soil firmly down around the stem and add water so that it packs closely around the cutting. Put an inverted beaker over each cutting. Label each flowerpot and put in the light but not direct sunlight. Water the cuttings regularly. The cuttings develop into new independent geranium plants.
3. Cuttings can form adventitious roots. You can propagate poppies, geraniums, fuchsias, chrysanthemums and black and red currants by cuttings. Fill two flowerpots with sandy potting compost. Take two cuttings with leaves on attached from a geranium. Make the cut close to and just under a bud. Sturdy shoots with leaves close together are the most suitable. Remove the bottom leaves from each cutting. Plant each cutting 3 cm deep in a flowerpot and water well so that the soil is packed tight around the cuttings. Put a beaker over each cutting but making sure you allow air to get in and out. Keep the soil moist and do not expose the cuttings to direct sunlight. After some time the shoots begin to grow. At the point where the cut was made adventitious buds have formed and have put out roots. This is the way a cutting develops into an independent plant.
9.93 Bud grafting, orange, rose, fruit trees, apple, pear, plum
See diagram 9.93: Budding and grafting, shield graft, saddle graft
Grafting is used to propagate plants where the tissues of one plant are physically fused with the tissues of another plant. It is used widely in commercial horticulture for propagating gymnosperm and dicotyledon trees and shrubs. Monocotyledons do not have enough vascular cambium, the thin layer between bark and wood, necessary for grafting. One plant, the stock or rootstock, is chosen for the qualities of its roots. The other plant, the scion, is chosen for the qualities of its stems, leaves, flowers or fruits. For successful
grafting, the vascular cambium of the stock and scion must be aligned so they can grow together. The scion and stock will fuse to form a single plant. A shoot from such a graft shows the character of the scion, not of the stock that nourishes the scion. Successful grafts are usually between closely related plants.
1. Remove a bud from a plant with a small strip of bark and cambium, then insert it into a T-shape slit in the stock. Tightly bind and wax the parts. If the two areas of cambium are in contact, they produce a callus that unites scion and stock. To obtain good quality fruit select only the best buds for the graft.
2. Bud grafting allows the following: 2.1. rapid multiplication of desirable plants from a single individual, 2.2. preservation of a type that does not come true from seed, navel orange and hybrids, 2.3. modification of the scion, apples and pears are grafted to dwarfing stocks to grow a smaller tree for convenience of size, 2.4. improved yield, grape varieties may yield better when not grown on their own roots, 2.5. extended climatic ranges using extreme climate tolerant root stocks, 2.6. disease resistance by grafting susceptible scions to resistant stocks.
9.94 Shoot grafting, citrus
See diagram 9.96: Whip and tongue grafting
The scion and stock will fuse to form a single plant. A shoot from such a graft shows the character of the scion, not of the stock that nourishes the scion. Successful grafts are usually between closely related plants. Citrus trees can be grafted on rootstocks of hardy orange. Insert a cut twig, the scion, into an incision on the stem or root of another plant, the stock. Bind the two tightly together to give firm contact between the cut surfaces. Cover the join with an antiseptic wax to prevent infection. The cambium tissue of the cut
surfaces of the scion and stock form a mass of callus, soft, thin walled parenchyma, that joins the two surfaces together.
9.95 Whip and tongue grafting, fruit and ornamental trees
See diagram 9.96: Whip and tongue grafting
1. Cut the stock within 10 cm of the ground level. Make a long slanting upward cut on the stock about 4 cm long.
2. Make a small downward cut on the stock to form a tongue near the top of the slanting cut. Make a similar slanting downward cut on the scion, leaving a bud midway on the opposite side of the cut. Make a tongue on the scion to correspond with the tongue on the stock.
3. Fit the tongue of the scion neatly into the tongue of the stock to hold the graft firmly in position. The cut surfaces must be flush.
4. Bind the graft with moistened string and apply some warm grafting wax or bituminous tree dressing, e.g. "Arberex", to make the joint airtight and watertight. In all grafting the vital area is the "cambium layer", the thin green layer that lies between bark and wood. See it in any young stem that is cut through diagonally. The cambium cells retain the power of growing and knitting with similar cells. When grafting, the cambium of the scion must be in direct contact with the cambium of the stock so the nearer the two cut surfaces can coincide in length and width the better. Other methods of grafting include the following: clematis (root grafting) rhododendron (saddle grafting) birch (inarching, one tree to another).
9.97 Roots from plant parts
See diagram 9.85: Potato
Obtain a box of sand and put it out of direct sunlight. Wet the sand thoroughly and keep it moist. Plant any of the following in the sand: 1. various bulbs, 2. cuttings of begonia and geranium stems, 3. a section of sugar cane stem with a joint buried in the sand, 4. a section of bamboo stem with a, joint buried in the sand, 5. carrot, radish and beet tops, each with a small piece of root attached, 6. an onion, 7. an iris stem 8. pieces of potato containing "eyes", 9. a branch of willow.
9.98 Potting mix experiment
Be careful using potting mix. Wear a mask so you do not hale any dust and do not shake the bag. Wash the hands and clothes after using the potting mix then store it in a cool place.
Soil is not suitable for potted plants because it can get compacted too quicky. A good potting mix will keep a balance between holding water and letting the water out so there is enough water for the roots without then becoming waterlogged. To stop too much soil being lost through the hole in the bottom of the pot, do not use a stone but use a piece of cotton cloth.
Prepare two control mixes: 1. Minimal nutrient mixture of coconut fibre (50%), pearlite (25%), and vermiculite (25%). 2. Good nutrition but poor texture mixture of volcanic rock dust (50%), and cow manure (50%). Test plants from a legume crop, a leafy crop, a fruit crop, and a root crop. For hothouse tests, use seedlings of basil, lettuce and tomato planted in 8 cm diameter peat pots. For a full sunlight test use seeds of bean, radish, rocket, spinach and tomato sown in 5 x 10 cm plastic pots. Test home-made and commercial mixes by comparing growth o fplants in them with growth in the controls. An example of a successful commercial mix may contain animal manure, hoof and horn meal, trace elements, potassium phosphate and  other constituents.
9.100 Abscisic acid, C15H20O4, plant hormone
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.
Preface
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, sites 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. If you cannot control insects by hand picking, ask the Ministry of Agriculture to recommend a chemical spray. All insect sprays are dangerous. Show the students how to use them safely. Do not get the spray onto the hands. Do not breathe in the spray. Wash the hands well after using spray. Keep the spray container in a safe place where students cannot get it. Spray on a day of no wind but if you must spray on a windy day, spray down wind. Make sure the spray does not blow on other people.