Foodgardens2

School Science Lessons
School food gardens for tropical regions
2009-09-01
Please send comments to: J.Elfick@uq.edu.au
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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 your hands. Do not breathe in the spray. Wash your 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.

Table of contents
6.9.1 Planning school food gardens
6.9.2 Choosing land
6.9.3 Choosing crops
6.9.4 When to grow crops
6.9.5 Clearing land
6.9.6 Preparing ground
6.9.7 Improving the soil
6.9.8 Planting crops
6.9.9 Seeds
6.9.10 Multiplying plants
6.9.11 Interplanting
6.9.12 Crop care
6.9.13 Mulching the soil
6.9.14.0 Composting
6.9.14.1 Humus
6.9.14.2 Organic materials for composting
6.9.14.3 Carbon / nitrogen ratio
6.9.14.4 The 3 methods of composting
6.9.14.5 Compost inspection
6.9.14.6 Starting composting for the school garden
6.20.01 NPK grade formula

6.9.1 Planning school food gardens
Goals
1. To get the students interested in the vegetable project
2. To involve the students in the planning of the project by discussion
Principles of teaching
Students will want to learn if the teacher can get them interested and make them feel that they are doing something they really want to do. The problem here is to get the students interested in growing their own food.
Students learn better if they learn by doing instead of just looking or listening. In this lesson the students have to find some answers and copy them into their notebooks.

Tell the students that you want them to help you plan the school food gardens and tell them about the seven steps of planning. Tell the students about the aims of your school food garden programme. The aim of the school food gardens is to learn how to grow vegetables for the school kitchen.
The vegetables grown should be:
1. suitable for school kitchen use and liked by the students,
2. part of a balanced diet,
3. a mixture of local and introduced vegetables.
What advice do agriculture field officers give about the following:
1. which part of the land to use and how to use it?
2. how should you prepare the land for crops?
3. which crops are suitable?
Before starting the school vegetables project, answer the following questions:
1. What amounts of vegetables do you need for the school kitchen?
2. Who will plant, look after, and harvest the crops?
3. When will they do it?
How much money can be spent on the gardens?
1. What tools, equipment, and chemicals are available in the school?
2. What do you need to buy in the town or get from the Department of Agriculture?
3. Where will you store tools, equipment, and chemicals?
4. Who will look after the students and issue them the tools?
5. Which part of the school land can you use for gardens?

6.9.2 Choosing land
See Appendix M
1. The choice of the land you can use for the school food gardens will depend on the following eight points:
1.1 Which parts of the school land are safe from land disputes, claims from villagers who may want part of the crop, safe from stealing by villagers and school boys?
1.2 What are the best places for raised beds and fields? The raised beds, 1.2 metres x 6 metres, should be near the kitchen and classrooms to be convenient for kitchen staff and practical agriculture teaching. For the fields you need large areas of land. These fields should be no farther than 15 minutes from the school.
1.3 What parts of the school land have the best soils for gardens?
1.4 What type of vegetation is already growing in the different parts of the school land? For example old school food gardens, old village gardens, coconut stands, regrowth, bush land, swampy land. How much clearing and cleaning will be needed in these places to prepare the ground for crops? Are there large trees growing in or near the gardens that can damage crops by shading or root competition?
1.5 Which parts of the land will need draining, fencing, or contouring to prevent soil erosion?
1.6 How much equipment and planting materials will be available?
1.7 How much labour and time will be available for clearing, planting, managing and harvesting? For example, how big can your gardens be if school maintenance time is one hour per student per day?
1.8 What total area of land will be needed to achieve the goal set for vegetable production? Your goal may be 2 / 3 of the root crops you need and all the vegetables needed for the kitchen.

2. Calculate how much land you need to plant crops to feed the students, and how many students you can feed for how many days using the crops planted.
2.1 Amount of sweet potato to feed to each student per day? Let K = 1.5 kg.
2.2 Number of students to feed in the school? Let S = 120 students.
2.3 Amount of sweet potato needed per day = K x S or 1.5 x 120 = 180 kg
2.4 How many days to feed sweet potato to the students? Let D = 30 days.
2.5 Total amount of sweet potato needed = K X S X D or 180 x 30 = 5 400 kg
2.6 What is the expected yield of sweet potato? Let Y = 2 000 kg sweet potato per hectare (per ha).
2.7 Amount of land needed = K X S X D / Y = 5 400 / 2 000 = 2.7
To feed 120 students, plant about three hectares of sweet potato every month.

3. If you have five hectares of sweet potato growing, how many days can you feed the students?
3.1 Area of the crop? Let A = 5 hectares, 5 ha.
3.2 Expected yield of the crop? Let Y = 2 000 kg per hectare
3.3 Total expected yield = A X Y or 5 x 2 000 = 10 000 kg sweet potato
3.4 How many students? Let N = 120.
3.5 Amount of sweet potato to feed to each student per day? Let K = 1.5 kg
3.6 The total amount of sweet potato eaten by the students per day = K X N or 180 kg sweet potato per day.
3.7 The number of days you can expect to feed sweet potato is equal to the total amount of the harvest divided by the amount that they will eat per day = A X Y / K X N = 10 000 / 180 = 56 days. So if you have five hectares of sweet potato to harvest you can expect to eat them for 56 days.

4. The daily diet of the students should contain about 0.5 kg per student per day of vegetables other than root crops and corn. Each day you should have one good meal of legumes. Climbing beans can be picked from raised beds and field beans can be picked from the root crop legume rotations in the fields.
4.1 One meal with both leafy vegetables, e.g. Chinese cabbage, and fruiting vegetables, e.g. egg plant.
4.2 One meal with aibika or pumpkin leaves or local vegetables.
4.3 One meal with banana or coconut.

5. The land you choose should be square or rectangular and the students can probably measure the boundaries in metres and calculate the area of each garden in hectares.
5.1 length (metres) X breadth (metres) = area (square metres)
5.2 length (metres) X breadth (metres) = area (hectares, ha) 10 000
5.3 100 metres x 100 metres = 10 000 square metres = 1 ha
5.4 You can mark metres on the classroom floor and let the students practice pacing them.

1. Discuss with students the points to be considered in choosing the land. Do this while walking with the students about the school grounds.
2. Show the students the land you have chosen for the gardens and give your reasons. The reasons should include as many of the eight points as possible. Do the students agree with the reasons for the choice?
3. Show the students how to pace 1 metre and calculate the area in hectares pacing around the land.
4. Show the land selected for school vegetable gardens
5. Make a map of the school food garden.
On the map note the length, breadth, area, the direction of North and position of nearby trees and buildings, water supply, direction of drainage, and position of gates and fences.

6.9.3 Choosing crops
See Appendix A | Appendix B | Appendix M | Appendix N
Discuss the needs of the school kitchen and what students like to eat.
When deciding which crops to grow consider the following five points:
1. What are the needs of the school kitchen? How much of each kind of vegetable do you need each week? How much food are students expected to get for themselves and not from the school kitchen, e.g. coconut, fruit, and the produce of the students' own weekend gardens? If your school is well organized, all the food that the students gather should go through the kitchen.
2. Which vegetables do students like to eat? It is no use growing a new kind of crop such as okra if the kitchen staff do not know how to cook it and the students will not eat it. However, it is a good idea to try some new vegetables to widen the experience of the students.
3. The vegetables should be part of a balanced diet. Each day the students' diet should be two parts grain and root crops and one part legumes or meat and one part a mixture of leafy vegetables and coconut and fruit. Students eat 1.5 to 3.0 kg of food per day. Which planting materials will be available when it is time to plant? Do not plant the same crop again in the same soil. Grow following crops in an arranged order, crop rotation. Tables A and B set out crop rotations for school food gardens. These lists show what can be grown next after you harvest the present crops.
4. Try to get examples or pictures of vegetables that the students may not know. Commercial seed packets often have good pictures so save these for teaching aids.
5. Make sure that students use the names of vegetables as in these teaching notes, e.g., sweet potato not "potato", aibika or hibiscus cabbage or bele or pele not "cabbage".

1. Tell the students about the five points to think about when deciding when to grow crops: needs of the school kitchen, what students like to eat, balanced diet, planting materials, and rotations.
2. Ask the students to help you make a list on the chalkboard of the vegetables they eat in the mess and in other places. Next to each vegetable show the amount eaten by: eat a lot, eat some, eat only a little, or not at all or like a lot, like a bit, not like at all.
3. Next to each vegetable write one of the following: S = grain (e.g. maize) or root vegetable (e.g. cassava, yam, taro) P = legume (e.g. sitoa bean, winged bean, pigeon pea, mung bean, cow pea) L = leafy vegetable (e.g. hibiscus cabbage, pumpkin tips, Chinese cabbage) (S is for starchy food, P is for protein food, L is for leafy vegetable, F is for fruit.)
4. Tell the students that for a balanced diet they should grow some of each of these types of food.
5. Suggest another food crop they could grow to make a balanced diet and write these on the chalkboard.
Explain that rotation tables list what can be grown after each type of crop. Think of what is already growing in each garden and decide which of the vegetables needed for the kitchen can be grown next.

6.9.4 When to grow crops
When to grow a crop depends on the following:
1. Suitable climate
If there are wet and dry seasons in your area when is the best time to plant?
2. Growing period
When do you want to start harvesting your crop? Count back the number of weeks of the growing period to decide the best time to transplant and plant.
3. Harvest Period
You can usually plant crops all at once and later harvest them during some weeks. To make the harvesting period longer, you can use succession planting, i.e. plant a few rows of sweet potato every week.
4. After completely harvesting a crop, wait at least two weeks before replanting to allow you to clean the field of an old crop and weeds and to give time for compost or fertilizer to mix in the soil. Keep the land bare of crops (bare fallow).
5. Crop Rotation
It is not easy to follow the crop rotation and get the crops harvested when you want the students to do it. For example, you do not want any of your crops to be ready for harvest during the long school holidays. Time your planting so that crops such as root crops or legumes are growing during that holiday time. So they should be ready to be harvest, or turned in as green manure, after the first term starts.
6. Garden calendar
Use a garden calendar to help you decide when to plant crops. The example included in the lesson should either be duplicated or drawn on the chalk board. Before the lesson make a crop calendar for using the crops chosen by the teacher and the students in the last lesson. Use one column for each raised bed or field. Work backwards from the time of first harvest to planting. Work forwards to end of harvest and fallow period.

1. The five points to think about when to grow crops:
1.1 Climate,
1.2 Time of first harvest and harvest period,
1.3 Crop rotation,
1.4 Growth period (seed to harvest)
1.5 Fallow period.

2. Use the blank garden calendar and crop rotation tables or copy them on the chalk board.
Deciding when to grow crops depends on:
2.1. Climate
2.2. Wet or dry season. What is the best time for growing a crop?
2.3. Growing period
2.4. How long from planting seed to harvest, or from planting seed to transplanting to harvest?
2.5. Harvest period
How long can you keep picking the crop?
2.6. Fallow period
This is when you rest the ground before planting a new crop. During the fallow period you can clean out all the plants from the last crop, pull out all the weeds, and dig in compost and fertilizer.

3. Crop rotation
The advantages of crop rotation are as follows:
3.1. Pests and diseases that infect a particular kind of plant or a particular family of plants cannot be passed on from one crop to the next crop. Root crops or leafy crops are examples of kinds of plants. Tomato, chilli, capsicum, European potato are all in the tomato family.
3.2. Different kinds of crops take in different amounts of plant nutrients from the soil. Legumes add nitrogen plant nutrient to the soil.
3.3. Different kinds of crops have different depths of roots and affect the way the soil holds together in different ways.

4. Crop rotation for our school food gardens.
4.1 Raised beds: e.g. 1. Chinese cabbage then 2. tomato then 3. winged bean then 4. Maize
4.2 Fields: e.g. 1. sweet potato then 2. cowpea then 3. cassava then 4. mung bean
4.3 Garden calendar for our school food garden
4.4 Date Bed 1 Bed 2 Field 1 Field 2
4.5 Planting: cabbage bean corn sweet potato

6.9.5 Clearing land
1. Clearing land is hard work and you must try to make sure that this work is not so hard that the students hate agriculture period. Most of this work should be done during school food gardening time or school maintenance time. Do not use agriculture periods unless students are learning something new from the work.
2. You can make hard work more interesting by:
2.1. always praising the best efforts rather than criticizing lazy or careless work,
2.2. arranging for a definite well organized work period, e.g. "all Form 1 students will cut bush between 3:00 p.m. and 4:00 p.m., working with me",
2.3. setting a realistic goal for each work period, e.g. "Let us try to finish the post hole digging this afternoon",
2.3 developing competition between classes, e.g. "Let us see if you can clear this land better than the other class". However, do not let boys compete against girls,
2.5 working with the students (do not do all the interesting part of the work yourself) OR training groups of students to work by themselves with a student leader.
3. Dig up some soil from badly drained land so students can smell it in the classroom. It is sour land.

1. To prepare land for vegetable gardens it must be cleared, drained and fenced.
2. Reasons for clearing
2.1 to stop competition for plant nutrients from other plants (weeds)
2.2 to allow cultivation (no logs, trees, roots or stones)
2.3 to stop shading of the crop from trees.
2.3 Land should be cleared twice before planting.
3.1 First clearing: cut down bushes and trees, remove logs, roots, stones and weeds
3.2 Second clearing: 3 weeks later pull out all new weeds. Put all weeds on the compost heap.
4. Reasons for draining
Soil with too much water is said to be waterlogged. Land that is not drained properly has a bad smell. The teacher should let the students smell the "sour" soil.
4.1 To allow air to get into the soil for the roots to breathe,
4.2 To stop diseases living in the soil that can attack the roots and stem base of crop plants.
5. Reason for fencing
5.1 To keep pigs and other animals out
5.2 To keep people out
6. After you have cleared the land there is a danger that if the soil is left bare, wind, rain and water can carry away the soil and destroy the gardens (soil erosion). Grow plants stop or slow the wind (windbreaks), e.g. Leucaena. If you cover the bare soil with mulch or a leafy crop, this will stop raindrop erosion. Water erosion can be stopped by good drains with grass growing in them. You can also lessen water erosion by making ridges and beds across a slope and not up and down it.

6.9.6 Preparing ground
See diagram 6.0: Digging the soil, raised beds and ridges | See diagram 61: Sweet potato garden
1. Prepare ground with treatments before planting which allow seeds to germinate easily and quickly, allow roots to penetrate the soil easily, improve the plant nutrients in the soil, and help to control weeds and insects.
2. Be prepared to tell the students that good preparation of ground does need hard work, but later the crops will grow better and you will need less work to look after them.
3. If beds and ridges run North South then all the plants in one row get the same amount of light. Their shadows fall on the interwove area, and not on each other.
4. Do the practical work of preparation of ground soon after the lesson. You may need other lessons to teach about raised beds or ridges.

1. Teach the need for good preparation of ground.
2. The objectives of preparation of ground are as follows:
2.1 to loosen the soil so roots can grow easily,
2.2 to make a fine even seed bed so seeds will germinate easily and quickly,
2.3 to control weeds and insect pests by digging them up,
2.4 to improve the soil by mixing in dead plants and compost. This will increase the plant nutrients in the soil and make the soil easier to dig,
2.5 to form the soil into raised beds or ridges so it is ready for planting.
3. The steps in preparing ground are as follows:
3.1 Turn the ground over to a depth of 15-30 cm. Work backwards using spades for turning and hoes for breaking up clods of earth. For raised beds use the trench digging method:
3.2 Dig in compost or other fertilizers. (Check if the Department of Agriculture allows compost because in some countries compost can contain pests and diseases.)
3.3. Use rakes and hoes to make the soil fine and even.
4. Raised beds should be 1.5 metres x 6 metres x 15 cm. Put logs around the sides of the beds. When beds are first made, you can pile the soil 30 cm high but it should settle down to about 15 cm. Hoe fields into ridges 45-60 cm apart and 15 cm high.

6.9.7 Improving soil
Bring to the classroom samples of sandy soil, clay soil, and a good soil.
1. Show the students handfuls of:
1.1 sandy soil that slips between the fingers,
1.2 clay soil that is sticky, you can make it into a ring,
1.3 good soil that is dark in colour, and forms crumbs when you open your hand (crumb structure).
Let the students feel the three soils in their hands.
2. You can improve soil for the gardens in five ways:
2.1. Improve the texture
Texture is the feel of the soil caused by the size of the soil particles.
2.1.1 Sandy soil has a coarse texture. The sand particles are too large. Sandy soils drain too quickly. Sandy soils feel rough.
2.1.2 Clay soil has a fine texture. The clay particles are too small. Clay soils may not drain at all and the soil becomes waterlogged. Clay soils feel smooth.
A good soil has a mixture of sand, clay and other particles between these sizes. You can improve soil texture by mixing soils with different sized particles, i.e. add sandy soils to clay soils add clay soils to sandy soils.
2.2. Improve the structure
A good structure is shown by the soil forming crumbs in the opened hand because the particles stick together. You can improve soil structure by digging well rotted compost into the soil. Use animal manure if they do not allow compost in your region.
2.3. Improve the tilth
Tilth means how well roots can pass through the soil. Roots can pass best through soil that is loose, contains air and water, and is free of stones. To improve tilth you dig the soil to a depth of 15-30 cm, take out stones then smooth the surface flat with a rake.
2.4. Improve the soil fertility by:
2.4.1 adding plant nutrients as well rotted compost, unless they do not allow compost.
2.4.2 adding animal manure or water in which animal manure is soaking.
2.4.3 adding green manure, dig in a legume crop such as cowpea when the flowers are forming.
2.4.4 adding wood ash, this contains potash (potassium oxide). The ash should be grey white in colour.
2.5.5 adding manufactured fertilizer, e.g. muriate of potash for potash, sulfate of potash for potash and sulfur, superphosphate for phosphorus and sulfur, ammonium sulfate for nitrogen and sulfur, mixed fertilizer (NPK) for nitrogen, phosphorus and potash.
2.5. Improve the pH
Most plants like soil to be a little bit acid (pH 6 to pH 7) If soil is too acid (pH 5 to pH 1) add lime such as burnt crushed shells or coral sand. If soil is too alkaline (pH 8 to pH 14) add well-rotted compost or ammonium sulfate.

6.9.8 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.

1. 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.

2. Imported seed
Advantages
2.1 They are free from diseases and insect pests.
2.2 All the plants grown from the seed in a packet will be the same.
2.3 The seed has been chosen to give a high yield.
Calculate exactly how much seed is needed and buy the number of packets.
Disadvantages
2.4 Imported seed is expensive.
2.5 There are many different varieties and it is hard to know which to choose.
2.6 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.
2.7 Imported seed may not be suitable for the tropical conditions.

3. Produce you own seed
Advantages
3.1 The cost of producing your own seed is less than imported seed.
3.2 Seeds that are chosen from the best plants in your garden should be suitable for the conditions in your garden.
Disadvantages
3.3 The plants produced may vary a lot due to genetic variation.
3.4 The seed may carry disease or insect pests if not treated with pesticide.
3.5 Seed may die if it not stored in cool dry conditions.
3.6 There may not be enough seed for your needs.

4. Methods of planting
The 3 methods of planting:
4.1 Direct planting of seeds and cuttings into the field
Advantages
4.1.1 It is a cheap and simple method
4.1.2 There is no damage due to transplanting
4.1.3 Plants are easy to look after. Surviving plants may be stronger
4.1.4 Some seeds must be sown this way. e.g. bean
Disadvantages
4.1.5 Less seed germinates so there are fewer baby plants
4.1.6 You have less control over what is grown in the field

4.2 Planting in a seed bed of fine even soil sheltered by a roof. Later chose the best plants for transplanting
Advantages
4.2.1 More seeds germinate and more baby plants live
4.2.2 It saves time because other plants can be growing in the field while baby plants are in the seed beds
4.2.3 You have more control over what is grown in the gardens
Disadvantages
4.2.4 It is an expensive and complicated method
4.2.5 It wastes time
4.2.6 Transplanting may damage roots.
4.2.7. You must water the plants every day.
4.2.8. Skill is needed to look after baby plants properly!

4.3. Planting in seed boxes sheltered by a roof
Sterilize the seed boxes and soil in them to kill pests and diseases. You can take the seed boxes to the field when transplanting.

1. Direct planting of seeds and cuttings
See Appendix C
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.
2. Seed bed planting
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.
3. Seed boxes
Use boxes that are about 24 cm x 24 cm x 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).
4. Planting potted plants
Dig a hole 4 X width and 2 X 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 dow 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.

6. Other methods of planting include the use of pressed plant matter, e.g. "Jiffy Seven" pots. Stand them in a shallow tray to take up water hen you can transplant without damaging the plants. Another technique is to collect beer cans, half fill with soil mixture and use one for each seed. Hardening off and transplanting is the same for both types of seed beds.

8. Plant seeds and other planting material in the following:
8.1 Long deep grooves in the raised bed or field (furrows). Use a hoe to make them.
8.2 Short shallow grooves in the seed bed called drills. Use a rake handle to make them.
8.3 Hills or mounds to allow all round drainage for sweet potato, corn and pumpkin.
8.4 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.

9. Plant pots
9.1 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.
9.2 Iron fish tins, drink tins and aluminium drink-cans may be used as containers, but they are not tapered. So you may have to 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. They are so cheap and plentiful that it is a good idea to experiment with these containers.
9.3 You can 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.
9.4 You can 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. 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.

10. Use a plant nursery for the three following reasons:
10.1 Give seeds and young plants the best conditions for germination and rapid growth.
10.2 Use the land for other purposes while the plants are in the nursery.
10.3 Prepare the land for planting right up to the time of transplanting.

11. 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.

12. 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 you should build walls and a door that you can lock to keep out animals.

13. 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.

14. 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.

15. 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 you should 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.

16. 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.

17. How to sterilize the 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.

6.9.9 Seeds
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 +10^oC to + 20^oC
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
See Appendix C | See diagram 9.122: Germination test | See diagram 5.5: Seeds planted at different levels

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.
% germination = (No. germinated seeds / No. seeds planted) X 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 such as 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.
8.
Method A, 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.
Method B, 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.

6.9.10 Multiplying Plants
See diagram: 5.5 Vegetative reproduction
Sometimes you can 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.

1. Cuttings
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. Division
This is a natural process when a plant forms new plants as offshoots. Parts of the plant grow to form new plants and later separate from the mother. 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.

3. Stooling
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. This can be used on guavas.

4. 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. This can be used on mango.

5. Marcotting or air layering
1. 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 a Ficus. 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.
2. 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.

6. Grafting
6.1 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.
6.2 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.

6.9.11 Interplanting
1. You can grow different kinds of plants in different rows in the same garden. This is called interplanting. 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.
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

2. 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. Some 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.

3. 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. You should try out some trials comparing single crops with interplanted crops e.g. bed 1 sweet potato, bed 2 corn, bed 3. sweet potato interplanted with corn.

1. Show the students examples of interplanting in your gardens or be ready to draw diagrams of examples of interplanting.
2. Ask the students if they can give you some samples of interplanting in village gardens. Write these on the chalk board. Ask the students why village people grow different kinds of food plants together. Write this on the chalk board, e.g. Do village people plant only one kind of yam in a yam garden, or do they plant different kinds together? Why do they do this?
3. Which crops are interplanted in the school food gardens? Write on chalk board. Write on the chalk board some other examples of interplanting.
4. The advantages of interplanting are as follows:
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.

6.9.12 Crop care
Think about the different jobs to do in the garden to look after the crops. Write 2 column headings on the chalk board: Garden jobs and Reasons. Remember a different job or a reason for doing the job and write all these on the chalk board.

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.

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.

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.

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.

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. Deep rooted plants like tomato, pumpkins and sweet potatoes should be watered every 2 weeks.

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.

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, see Topics 18 and 19.

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.

9. 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. Crotalaria, Centrosema, Pueraria or cowpea. This will protect the soil from erosion, control weeds, and put some nitrogen plant nutrient in the soil.

10. Other jobs
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.

11. Diary
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.

6.9.13 Mulching the soil
Mulching is a thick layer of leaves, dry grass, or husks over the soil. It 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. 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.
Mulch should not touch plant stems because it may cause an infection of collar rot.

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. You should always 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

6.9.14.0 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 our 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.

6.9.14.1 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 manures, 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 acvailable 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 Rhizobia in small nodules on the roots of legumes and blue-green algae in wet soils. However, some denitrifying bacteria in wt soils convert nitrates back into nitrogen gas and so make nitrogenous substances unavailable to plants.

6.9.14.2 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.

6.9.14.3 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.

6.9.14.4 The 3 methods of composting
1. Heap on the ground
Make compost heaps about 2 m X 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.

6.9.14.5 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 55 to 60^oC. Bigger heaps get hotter than smaller heaps. If the temperature of the heap rises above 60^oC 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 hemi-celluloses. 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%.

6.9.14.6 Starting 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.