Foodgardens3

School Science Lessons
School food gardens for tropical regions
2013-05-17
Please send comments to: J.Elfick@uq.edu.au

Table of contents
6.9.17.0 Fertilizers
6.9.16.0 Legumes, bean, pea
6.9.16.1 Rhizobium, root nodules in legumes
6.9.17.2 Soil acidity, pH
9.7.0 Soil improvement

6.9.17.0 Fertilizers
6.34a Chemical fertilizers (Primary)
9.14.0 Composting
6.9.17.1 Fertilizers, straight fertilizers and mixed fertilizers
5.18: Fertilizing the soil
6.33 Fertilizing soil (Primary)
9.9.18 Hydroponics, soil-less culture solutions
6.9.15.3 Liquid manure
4.35 Natural fertilizers (Primary
5.25: Plant nutrients from plant ash
12.14.5: Superphosphate production
6.9.15.5 Tests for adding gypsum to the soil

6.9.16.0 Legumes, bean, pea
6.9.16.0 Legumes, bean, pea
6.9.16.01 Legumes, Different legumes
4.29 Bean flower, (winged bean) (Primary)
4.28 Bean life cycle (Primary)
4.30 Bean seeds and pods, (Primary)
41.0 Classification of the common bean species
4.27 Collect bean plants (Primary)
6.9.16.10 Common bean
6.9.16.9 Cowpea
6.6.17.1 Energy from peanuts
5.27 Germinate bean seeds, (Primary)
6.9.16.5 Growth habit of legumes
6.9.16.3 History of legumes
6.9.16.2 Legume cover crops
9.5.12 Legume pod fertilization
9.72 Legume roots, broad bean, clover
4.26 Legumes (Primary)
6.9.16.4 Legumes in the diet
6.9.16.8 Mung bean
6.9.16.6 Planting legumes
7.8.3.6 Prepare bean curd, (tofu, soya bean)
9.155 Respiration apparatus, tests for respiration of soaked peas with limewater
6.6.9 Respiratory quotient of Compositae flowers, mung bean seedlings
9.75 Root hairs of germinating bean plant
6.6.4 Tests for respiration of soaked peas with limewater
4.25 Uses of peas and beans (Primary)
6.9.16.1 Uses of legumes
6.9.16.11 Winged bean

6.9.16.1 Rhizobium, root nodules in legumes
9.71 Rhizobium in legumes
9.72 Rhizobium, Legume roots, broad bean, clover
6.9.16.7 Rhizobium inoculation
4.3.13 Isolate micro-organisms from root nodules
4.3.12 Root nodules, nitrogen-fixing bacteria

9.7.0 Soil improvement
9.7.0 Soil improvement
9.7.1 Soil texture
9.7.2 Soil structure
9.7.3 Soil tilth
9.7.4 Soil fertility

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

6.9.16.0 Legumes
See diagram 9.72: Root nodules | See diagram 9.72.1: Legumes: winged bean, pigeon pea, mung bean | See diagram 9.72.2: Winged bean flower
Plants from the bean family called legumes are very important for school food gardens because you can use them for protein food, as a green vegetable and for green manure and cover crops. In this lesson teach students to recognize different plants in the legume family. To prepare for this lesson, collect 3 examples of legumes: food plants, cover crops or green manure, large trees. Also, collect
examples of plants which are NOT legumes. In this type of lesson. you do not tell the students the answers. Instead you let them look at the plants and discover a set which have similar characters. The students should find out for themselves what "legume" means.
Divide the class into groups of 4 to 5 students. Give each group one of each kind of legume and some plants which are not legumes. Tell the students to look at all the plants carefully and then make a set of plants which have similar characters. Let the students talk about this. Go to each group and help the students make their set but do not tell them the answers. Let the students walk around from group to group so they can compare the sets. Stop the students from moving about and show them the correct sets. Ask the students to tell you the common characters of the set. These are as follows: shape of leaves, shape of flower, the number of parts in the flower and the nodules on the roots. The roots have lumps on them called nodules. These nodules contain Rhizobium bacteria called which
can use nitrogen gas from the air. When the plant dies this nitrogen in the plant can then be used as plant nutrient by other plants.
Now you can tell the students that the set of plants which look the same are all members of the legume or bean plant family. Ask them if they could find other legumes in the gardens and in the bush. You can give the students some work for the next lesson tell them that each student must bring to the next class a legume plant which they did not see in the class today.

Resource material, Legumes
Legumes are plants of the bean family (Fabaceae). Most of the plants have lumps on their roots called nodules. Rhizobium bacteria can live in these nodules and use nitrogen gas from the air. When the legume plant dies and rots other plants can use this nitrogen. In this way legumes improve the fertility of the soil. When you dig a legume crop into the soil it is called a green manure.
Leaves and flowers
Legumes are easily recognized from the leaves and the flowers. The leaves are usually compound leaves, often with each leaf divided into 3, 5 or more leaflets. The flower contains 5 sepals and 5 unusual petals 1 large standard petal coming from the back, 2 wing petals at the side and 2 keel petals which may be joined below. There are 10 or 9 + 1 stamens which are stuck together to form a tube. The fruit is a pod formed from one carpel which can break into two to let the row of seeds out. The flowers are normally
self-pollinated but they can be cross pollinated by large insects such as bees which can push down the keel petals and get into the flower.

6.9.16.01 Legumes, Different legumes
1. Winged bean or four angled bean or "as bin" or Goa bean, should be grown in all school food gardens because the seeds have a high protein content. You can eat the seeds, green pods, leaves, flowers and tubers.
2. Cowpea, snake bean, yard long bean, lablab bean, are closely related. They are grown for the seeds and pods and as a green manure crop.
3. Peanut (ground nut) has a high protein content and the plant is a good animal feed. The peanut must be roasted or boiled before eating.
4. Mung bean or green gram bean, have pods have a high protein content and the seeds can be left to sprout then eaten. The pods are rather small and students get tired of picking them. It is also a good green manure crop.
5. Soya bean (soy bean), has seeds that are are very nutritious but this plant is attacked by lots of diseases in the wet tropics.
6. Chick pea has large seeds which are very nutritious.
7. Pigeon pea is a perennial bush which can be used as temporary shade.
8. Other shade trees include the "cocoa shade" albizia, cassia, coral tree, gliricidia, leucaena, poinciana (flame of the forest), wattle.

6.9.16.1 Uses of legumes
You can eat the following parts of the legume plant: 1. Tender young leaves, e.g. Pigeon Pea, 2. Unripe pods picked when still green or light yellow, e.g. Cowpea, 3. Dried seeds called pulses, e.g. Soya bean, mung bean, pigeon pea, 4. Sprouted seeds, e.g. Mung bean, 5. Tuberous roots, e.g. Winged bean.

6.9.16.2 Legume cover crops
Legumes may be grown between tree crops to cover the soil and stop weeds growing by shading them. These crops are called cover crops, e.g. the trailing plants, pueraria and centrosema . Erect plants such as crotalaria and cowpea are grown as green manure. If you dig these plants into the soil at the time of flowering nitrogen plant nutrient is added to the soil. Some legumes which are trees or shrubs are grown to provide shade or windbreaks, e.g. leucaena. Legumes which are large trees and have large beautiful flowers are grown for shade and decoration, e.g. coral tree.

6.9.16.3 History of legumes
Legumes are a very old food. The story in the Bible of Esau and Jacob and the "mess of pottage" refers to a porridge made of dried legumes called red lentils. In some parts of the Bible it says that legumes are a food for poor people only. However, when Nebuchadnezzar, King of Babylon, ordered that some of the children of the Israelites be given some of the King's meat every day, Daniel changed this to more simple food. After the children had eaten pulses and water for 10 days, they appeared healthier than those who ate the King's meat.

6.9.16.4 Legumes in the diet
You can use legumes food in 2 main ways:
1. The unripe green pods and seedss and sometimes also the tender green leaves are picked and cooked as a vegetable. These provide plenty of vitamins if eaten soon after picking. French people call the green pods "mange tous", eat all peas.
2. The pods are picked when almost dry before they split and let the seeds out. They are then dried in the sun and threshed by putting in a bag and hitting it with a stick. The dried seed called a pulse is stored and later boiled and eaten. Pulses are an easily digested and nutritious food. They contain about 20% protein, 60% carbohydrates and 3% minerals (especially calcium and phosphorus) and vitamins. The type of protein is not enough for a balanced diet so some animal protein is still required in the diet. Before cooking, pulses should be soaked in warm water overnight and the water thrown away. This reduces the production of gas during digestion. They are cooked by boiling for up to 1 hour.

6.9.16.5 Growth habit of legumes
Legume plants may be erect, spreading, trailing or climbing. The plants usually produce flowers and fruit over some weeks which require more than one picking. Usually the trailing plants have the longest harvesting period. Climbing plants save space in the vegetable garden.

6.9.16.6 Planting legumes
Legumes can grow in different types of soils but they should be deeply dug and well drained to allow roots to grow easily and prevent attacks by fungus and nematode worms in the soil. They are usually planted towards the end of the rainy season 3 cm deep in rows 50 cm apart between rows and 30 cm apart within the rows, or planted closer and thinned out to 30 cm.

6.9.16.7 Rhizobium inoculation
Nitrogen fertilizer is not normally needed because the plants can fix nitrogen from the air with their root nodules. However, if legumes are being grown in a soil for the first time there may not be enough nitrogen-fixing bacteria, Rhizobium. To provide enough bacteria the seed should be mixed with the correct type of bacteria just before planting. This is called inoculation. To inoculate, e.g. cowpea seed, mix the contents of the packet of cowpea inoculant with water and pour it over the seed so they become evenly coated. For slurry inoculation, make a slurry by mixing the contents of the packet with 500 mL water for small packets and 2 000 mL water for larger packets. Use a Legume Seed Inoculation Chart provided by agricultural chemical companies to calculate the amount of inoculant for the type and amount of seed, For example:
Table 6.9.16.7 Rhizobium inoculation

Group	Used for inoculating	Small packet (70 g)	Large packet (250 g)
.	.	To treat Kg of seed	To treat Kg of seed
Mung	Mung bean	.	100
Cicer	Chick Pea, Cicer	25	100
Centro	Centrosema	10	50
Desmodium	Desmodium	5	25
Leucaena	Leucaena	25	100

6.9.16.8 Mung bean
See diagram 9.72.1 Mung bean, winged bean, pigeon pea
The crop matures in about 3 months and is harvested over some weeks as the pods ripen. The pods tend to split so it is best to harvest pale yellow pods in the mornings and let them dry in the sun. They are easy to thresh by hand to put them in a bag and beat it. The stored bean may be damaged by insects if not kept dry. Mung bean can be boiled and eaten as a vegetable, or boiled and mashed with sugar or syrup, or boiled and eaten cold with onion, oil and vinegar. The Mung bean can be sprouted by soaking seeds
and then letting them sprout for 3 to 4 days. Before cooking Mung bean the seeds should be soaked in warm water overnight and that water thrown away.

6.9.16.9 Cowpea
Cowpea come from Africa and many varieties have been produced, e.g., snake bean or yard long bean or asparagus bean. Both unripe pods and young leaves are used as a vegetable. The ripe dry seeds are very nutritious and are easily digested if well cooked. The plants can grow in a wide range of soil types providing they are well drained. It is an annual leafy plant which can also be used as a cover crop. There are many different types from erect to trailing and climbing. Flowers are white to purple on long flower stalks. Pods are smooth and slightly curved and yellow when dry. The seeds may have a dark spot where it was joined to the pod to give it a "black eye". The colour of the seed is brown to purple. The flowers are naturally self-pollinating. Seeds of erect varieties should be planted in firm moist seed bed in rows 50 cm between rows and 10 cm within rows. Avoid time of high rainfall and too much fertilizer or the plants will produce lots of leaves but few pods. Spreading varieties should be planted 30 cm apart and climbing varieties can be planted in hills 80 cm apart. Weeds should be pulled out by hand-picking when still young. There are few diseases and they can be controlled by garden hygiene and rotations. Erect varieties have a short harvest period and climbing varieties have a longer harvest period and yield a lot more for the area of garden used. Pods and seeds are easily attacked by fungus diseases in wet weather. The seeds are hard to store without treating with pesticides.

6.9.16.10 Common bean (haricot bean, kidney bean, French bean, snap bean, field bean)
There are many kinds of these bean which come from Central America. They are grown as a green vegetable and for the dried seeds. The seeds must be soaked in warm water overnight, the water thrown away and then well cooked otherwise they cause gas in the intestines. These bean often do not grow well in coastal areas of the tropics because the high humidity allows them to be attacked by many pests and diseases. The seeds should be sown in deeply dug well drained soil 3 cm deep, 60 cm apart between rows, and 10 cm apart within rows. The soil must be loose and fine to allow the stem to lift the cotyledons easily through the soil. Although they are legumes they need a lot of nitrogen in the soil. Bean are erect annual plants which mature in 6-8 weeks and can usually be harvested in 2 pickings. They cannot withstand very hot weather. The seeds store well when dry, especially the red seed varieties. There are
many pests and diseases. Bean fly cause the stems of young plants to split and go brown. Small brown egg-shaped cocoons can be seen inside the attacked stem. They can be sprayed with Dimethoate, a dangerous chemical. Bean pod borer is hard to treat because it is a caterpillar which gets inside the pod. Spider mites cause yellow spots on the leaves in dry weather they can be controlled by Dimethoate.

6.9.16.11 Winged bean ("as bin", Goa bean)
See diagram 9.72.1: Mung bean, winged bean, pigeon pea | See diagram 9.72.4: Winged bean flower
This is a traditional crop in Papua New Guinea. People eat the flowers, young leaves, green pods, dry seeds and tubers. The dried bean can contain 33% protein and the tubers 10% protein. The plant grows in almost any type of soil which is well drained. It is a long vine which must be supported on stakes. The large pods have "wings" on them. Some varieties produce mostly pods and some produce mostly tubers. Seeds are planted 3 cm deep, 20 cm × 20 cm apart in raised beds or mounds, at the start of the wet season. They can be interplanted with corn or soybean. Fertilizer and inoculation is not usually needed. Weeding should be done early to protect the young plants from competition for water. When the crop is 6-8 weeks old stakes or string 2 metres high should be provided to let the plant climb. The main diseases are leaf spot which can be controlled with Benomyl 50 gram / 100 litres water and soil pests and diseases which can only be controlled by rotation. Collar rot can only be controlled by shallow planting in well-drained soils. Flowers, leaves and green pods can be harvested after 3 months and tubers after 5 months.

How to use the winged bean plant as food:
Pods
Winged bean pods are the most popular part of the plant in almost every country where it is grown. Tender pods may be eaten raw or else chopped and then either boiled in water or coconut milk, or shallow-fried in oil. The winged bean is also used in soups, and stews. Pods which are too fibrous to eat whole are often steamed or baked in open fires, and the seeds scraped out and eaten. The seeds may first be removed and then boiled or fried.
Leaves, shoots and flowers
The growing shoots, young leaves and flowers of the winged bean are edible, nutritious and delicious. They may be boiled or fried.
Ripe seeds
Winged bean seeds should be soaked until the seed coat starts to soften. They can then be boiled in water until they are tender, or they may be shallow fried or baked. It is best to soak the seeds in water beforehand to breakdown some of the toxic substances. The winged bean seed contains about as much protein and energy as the soybean.
Root tubers
Tubers can be boiled or baked (but not fried) without peeling. The skin then peels off easily. The root should not be eaten raw.

6.9.17.0 Chemical fertilizers, grade formula
See 12.14.5: Superphosphate production
Grade formula of artificial fertilizers
If the fertilizer contains 13% nitrogen, 13% phosphorus and 21% potassium, 100 grams of the fertilizer would contain 13 g nitrogen, 13 g phosphorus and 21 g potassium, the grade formula is NPK =13:13:21.
Other examples of the grade formula of artificial fertilizers: muriate of potash (NPK = 0:0:50), superphosphate (NPK = 0:9:0), sulfate of ammonia (NPK = 21:0:0), urea (NPK = 46:0:0).
The term "potash" applied to mixed fertilizers refers to "K₂O equivalent", but not to K₂O itself, because it is not included in a mixed fertilizer.
1. Chemical fertilizers are made in factories. Some are made from minerals which occur naturally and are later ground to a powder and sometimes treated with chemicals, e.g. ground rock phosphates and superphosphate. Other fertilizers are chemicals in chemical factories e.g. sulfate of potash (potassium sulfate). In this topic you will refer to chemical fertilizers as "fertilizers".
2. Some people think that students should not be learning about imported fertilizers. However, many tropical soils are lacking in certain plant nutrients, e.g. potash, and the use of a small amount of these fertilizers can greatly increase the yield of the food crops. Imported fertilizers are costly but if they are used according to the recommendations of the Department of Agriculture and are stored properly they should pay for themselves in the increased value of the crop yield. Do some fertilizer trials. Then you can make your own decision about whether it is cost effective to buy and use imported fertilizers.
3. A good design for a fertilizer trial is as follows:
Table 6.9.17.0

Block 1	Block 2
Block 3	Block 4

In each block plant 20 cuttings of potato. Blocks 1 and 4 are experimental blocks. Put one teaspoon full of fertilizer in the soil around each cutting. Blocks 2 and 3 are control blocks, so do not use any fertilizer. Harvest each block separately and weigh the potato.
Compare the weight of potato from Blocks 1 and 4 with the weight from Blocks 2 and 3. Compare the value of the harvests if they were sold. Generally speaking, it pays to use fertilizer if the use of fertilizers can at least double the yield, i.e. weight of blocks (1 + 4) / weight of blocks (2 + 3) / 2.
4. Use fertilizer to make a profit.
Profit = (returns from Blocks 1 and 4) to (returns from Blocks 2 and 3) to cost of fertilizer used.
Cost of fertilizer in bags = (cost of fertilizer + freight) × (weight of fertilizer used / weight of whole bag of fertilizer)
5. The following is an example of a lesson that you could give on chemical fertilizers. You will need a fertilizer bag. This lesson could be followed by a lessons on how to put fertilizers in the soil.
1. Show the students where chemical fertilizer has been used in your school food gardens, or ask them whether they have seen it used in a plantation.
2. Show the students a bag of fertilizer. Let them read: 2.1 The name of the factory which made it, e.g. CFL Consolidated Fertilizers Limited, 2.2 The weight of the fertilizer, e.g. 50 kg, 2.3 the grade formula e.g. NPK 12:4:19. This means that 100 grams of the fertilizer contains 12 grams of nitrogen, 4 grams of phosphorus and 19 grams of potassium.
3. Ask the students whether they think it is a good idea to use this imported fertilizer. Ask them to tell you the advantages and disadvantages of using it.
Advantages: 1. Fertilizer provides plant nutrients. 2. Fertilizer increases the yield and the value of a crop.
Disadvantages: 1. Fertilizer is costly. 2. If fertilizer is not used properly it is wasted. 4. Let the students put some fertilizers in their hands. Do not let them taste it but they can smell it.

6.9.17.1 Fertilizers, straight fertilizers and mixed fertilizers
1. Simple or straight fertilizers contain only one of the main plant nutrients and usually some other plant nutrient. Single superphosphate contains mainly phosphorus and it also contains some sulfur and calcium.
Muriate of potash contains potassium and chlorine.
Mixed fertilizers contain a mixture of simple fertilizers so that nitrogen, phosphorus and potassium may all be present as well as other plant nutrients. These fertilizers can be mixed before putting them in the soil or they can be bought already mixed, e.g. "Thrive" and "Zest".
Compound (or composite) fertilizers contain nitrogen, phosphorus and potassium in various forms of chemicals such as ammonium phosphate nitrate. They also contain other plant nutrients. Some of these are slow release fertilizers such as IBDU which slowly releases urea into the soil, also "Osmocote" which slowly releases an NPK mixture.

2. Some fertilizers have high concentrations of plant nutrients and are called high analysis fertilizers, e.g. triple superphosphate. Some fertilizers are made in the factory as granules or pellets. They give plants the correct mixture of plant nutrients at all times and are thus better than mixtures.

3. The contents of fertilizers are shown by a grade formula which uses the chemical symbols of the primary plant nutrients NPK. This is used in two ways, e.g. The old way listed the contents of potassium and phosphorus as their oxides. If the fertilizer contains:
Table 6.9.17.3

Previous formula	-	Current formula	-
13% Nitrogen	N	13% Nitrogen	N
13% Phosphorous Oxide	P₂O₅	13% Phosphorus	P
21% Potash	K₂O equivalent	13% Potassium	K

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

5. Current formula
The current formula lists the contents as the elements nitrogen, phosphorus and potassium. If the fertilizer contains 13% Nitrogen N 13%, Phosphorus P 21%, and Potassium K, this means that 100 grams of the fertilizer would contain 13 g nitrogen, 13 g phosphorus and 21 g potassium. The fertilizer is shown as NPK =13:13:21.
Fertilizers containing a high concentration of plant nutrients and are called high analysis fertilizers, e.g. triple superphosphate. Some fertilizers are manufactured as granules or pellets that give the correct mixture of plant nutrients at all times and so are better than mixtures.
Table 6.9.17.5 Examples of the NPK grade formula of fertilizers

.	NPK previous formula %	NPK previous formula %	NPK previous formula %	NPK current formula %	NPK current formula %	NPK current formula %
Fertilizer	N	P₂O₅	K₂O	N	P	K
Muriate of potash	0	0	60	0	0	50
Superphosphate	0	22	0	0	9	0
Sulfate of ammonia	21	0	0	21	0	0
Triple superphosphate	0	47	0	0	20	0
Urea	46	0	0	46	0	0

6. There are 4 methods of adding fertilizer to the soil:
6.1 Broadcasting
The fertilizer is spread over the surface of the soil by hand or by machine. It should then be dug into the soil using a hoe or plough because if left on the surface nitrogen plant nutrient may be lost as ammonia gas. Fertilizer dug into the soil about 2 weeks before the crop is sown is called a base dressing.
6.2 Banding
The fertilizer is placed below the surface of the soil by hand or by machine. A furrow is dug between the rows of seeds at a depth of about 2 cm deeper than the seeds, the soil is then turned to cover the band of fertilizer. Banding is done at about the same time as the seed is sown.
6.3 Top dressing
The fertilizer is spread after the crop has been sown. This is usually done with nitrogen fertilizer to provide extra plant nutrient at certain times to make more shoots and leaves. However, nitrogen plant nutrient may be easily washed out of the soil so it is best to add some of the fertilizer by banding at sowing time and add the rest by top dressing when the shoots and leaves are growing.
6.4 Side dressing
The fertilizer is placed between the rows by banding or placed under the plants and watered in after the crop has been growing for some time. This is done for maize (corn) vine crops and tree crops to increase the yield of fruit.

7. Straight fertilizers, simple fertilizers, NPKS
Table 6.9.17.7

Common name	Chemical formula	Approximate composition
1. Nitrogen fertilizers	.	.
Sulfate of ammonia (ammonium sulfate)	(NH₄)₂SO₄	21% N and 24% S
Nitrate of potash (potassium nitrate)	KNO₃	38% K and 13% N
Nitrate of soda (sodium nitrate)	NaNO₃	16% N
Urea	CO(NH₂)₂	46% N
2. Phosphorous Fertilizers	.	.
Single superphosphate	Ca(H₂P0₄)₂ + CaSO₄	0.9% P, 10% S, 20% Ca
Triple superphosphate	Ca(H₂PO₄)₂	19% P, 02% S, 16% Ca
"Special" superphosphate	.	Superphosphate + Copper or Zinc or Molybdenum or sulfur.
3. Potash Fertilizers		.
Muriate of potash (Potassium chloride)	KCl	50% K
Sulfate of potash (Potassium sulfate)	K₂SO₄	40% K and 16% S
4. Epsom salts (Magnesium sulfate)	MgSO₄	.
5. Sulfur	S	99% S
6. Gypsum	CaSO₄.2H₂O	18% Ca and 14% S

8. Mixed or compound fertilizers
They have many different compositions, e.g. 12% N, 4% P, 19% K, 10% S (high in potassium and sulfur), 12% N, 14% P, 10% K, 3% S (high in phosphorus). Osmocote is made with many different compositions but IBDU contains 33% Nitrogen. Only certain
forms of nitrogen fertilizer are suitable for controlled release in the tropics. Most dump their nitrogen. The estimated lasting period of 0.7 to 2.6 mm granules of IBDU depends on pH, water holding capacity of the soil and temperature.

6.9.17.2 Soil acidity, pH
See 5.19: Acid soils and alkaline soils
Some successful farmers claim that a soil pH of 6.2 to 6.5 is ideal for most food plants.
The acidity of a soil is measured by the pH scale. Numbers are used after pH to show whether the soil is acid or alkaline:
pH 1-2 very strongly acid, pH 5-6 weakly acid, pH 7 neutral, pH 8-9 weakly alkaline, pH 13-14 very strongly alkaline.
Table 6.9.17.2 pH

pH	pH	pH	pH	pH	pH	pH	pH	pH	pH	pH	pH	pH	pH
1	2	3	4	5	6	7	8	9	10	11	12	13	14

In pure water, the number of H⁺ ions = the number of OH^- ions, so water is neutral. In an acid soil there are many more H⁺ions than OH^- ions. In alkaline soils there are more OH^- ions than H⁺ ions. When a chemical fertilizer is added to a soil, it dissolves in the soil water and breaks up into positive ions and negative ions like the water molecule. For example when muriate of potash fertilizer, which is potassium chloride, is put in the soil, it adds to the soil potassium ions, K⁺ and chloride ions, Cl^-. These ions become attached to the clay particles and organic matter particles in the soil. However, if the soil is too acid or too alkaline, the large number of H⁺ions or OH^- ions will interfere with the attachment of fertilizer ions to soil particles. They may cause the fertilizer ions to be held too strongly to the soil particles. If this happens, the nutrient ions cannot be used by the roots of plants and you say that the nutrients are unavailable to the plants. For example if the soil is too acid, calcium, magnesium, potassium, sulfur and nitrogen are not very available to plants. In Australia, aluminium and other trace elements may be toxic to plants growing in acidic soils because these elements inhibit root growth. Soil acidity can be managed by the application of agricultural lime but this is not economic for broad-scale agriculture. If the soil is too alkaline, iron, manganese and aluminium are not available to plants. Copper and zinc are not available when the soil is too acid or too alkaline. If the fertilizer ions are held too weakly to the soil particles, then they will be easily washed out of the soil by heavy rain, and will be lost to plants. So if you want to use fertilizers properly, it is best if you can make sure that your soil is slightly acid but not strongly acid or strongly alkaline. If the soil is too alkaline, then many plant nutrients like iron, manganese, boron, copper and zinc will not be very available to plants. It is a good idea to use the fertilizer mixtures recommended by the Department of Agriculture. It only pays to use imported fertilizers if the plants use it to increase the amount of food they produce. Do not use the wrong mixed fertilizer, e.g. if you use a mixed fertilizer high in nitrogen on potato, it will only form a lot of leaves and little tubers.

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

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

3. Raise soil pH by adding agricultural lime or dolomite. A 1:1 mixture of the two may be best. Lime / dolomite (g / m²), To raise pH of the top 10 cm about 1 pH unit.
Table 6.9.17.6

Soil type	Lime / dolomite (g / m²)
Sands	100
Loam	200
Clay soils	300 to 400
Organic soils	600

Lower the pH of slightly alkaline soils (pH below 7.5) with agricultural sulfur.
Sulfur (g / m²) To lower pH of the top 10 cm by about 1 pH unit.
Table 6.9.17.7

Soil type	Sulfur (g / m²)
Sands	25
Loam	50 to 70
Clays	100

The large amounts of solid lime often present in alkaline soils with pH values higher than about 7.5
make it almost impossible to make these soils acid.

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

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

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

6.9.18.0 Pesticides
1. Do not attempt to teach lessons on this until you have carefully read the following section on Resource Material on pesticides.
2. Do not teach this lesson until you have shown students how to use the spray using water only. These notes will show you how to teach lessons on insecticides if you want to spray your hibiscus cabbage (aibika or bele or pele) plants because they are badly attacked by leaf miners.
3. The main aim of these lessons is to teach students how to use carbaryl insecticide safely. You will need insecticide concentrate, a sprayer, a plastic bowl and mixing stick, a 5 g measure and 4 L of clean water.

Method
1. Show students the damage done by the leaf miners to aibika or bele. Tell the students that you do not like to use pesticides, but in this case you must use a pesticide because it is the only way to save your aibika or bele crop.
2. Show the students the tin of concentrate. Let them read the label. Note the name of the company which makes the insecticide, the trade name of the chemical, the common chemical name, the weight of the contents.
3. Now let the students read from the label: "for the control of caterpillars, plant bugs, leaf-eating beetles and earwigs". Ask them whether this is the right insecticide for the job.
4. Read out to the students from the label. "This concentrate is dangerous if swallowed, breathed in or absorbed through the skin." Tell them what to do if these accidents happen.
5. Read the instructions: "apply 5 Grams in 4 litres of water". Show the students how you will measure 5 grams of the powder and how you will measure 4 litres of clean water.
6. Read the mixing instructions. "Mix the required amount of insecticide with a small quantity of water to form a cream and pour into remainder of the water.
7. Measure out 5 grams of the powder into a plastic bowl, use some of the measured 4 litres of water to make a smooth paste, pour about 2 litres of water into the spray, pour the insecticide paste from the bowl into the sprayer, use some water from your original 4 litres to wash out the plastic bowl and pour that into the sprayer, put the rest of the 4 litres of water into the sprayer, close the sprayer tightly and shake it.
8. Tell the students to remember: 1. what to read on the insecticide tin, 2. how to make up the spray. In the next lesson, you can show them how to use this spray.

Resource material to Pesticides
Use only the procedures, agricultural chemicals and insecticides recommended by the local field officer of the Ministry of Agriculture.
6.9.18.1 Caution before using pesticides
You must read these notes!
1. Pesticides are chemicals which can kill living things which attack plants and animals. There are different kinds of pesticide:
1.1 Insecticide kills insects, Fungicide kills fungus and sometimes bacteria,
1.2 Miticide or acaricide kills mites and spiders,
1.3 Nematicide kills nematode worms,
1.4 Molluscicide kills slugs and snails,
1.5 Rodenticide kills mice and rats,
1.6. Herbicide or weedicide kills weeds.
2. Do not use any pesticides which are not mentioned in this chapter. All pesticides are dangerous to humans, especially children, so they must be used and stored with great care if they are used in school food gardening. Use pesticides only if there is no other way of saving your crop. If you want to use pesticides always tell the headmaster what you intend to do.
3. The rules for using pesticides are as follows:
1. Read the directions on the container before opening. Make sure that you have the right pesticide for the particular pest. Make sure that you understand how much pesticide to use. Make sure that your sprayer and tank is clean and working. Try it out with water first.
2. Do not breathe in pesticide or spill it on your skin don't smoke or eat when using pesticides. If you spill pesticide on your skin wash it off with plenty of soap and water straight away.
3. Wear special protective clothing and wash yourself after spraying. Always handle concentrates with rubber gloves which you keep for that purpose only. Wear a work shirt buttoned down to the wrists, long trousers and boots.
4. Spray on a calm day.
5. After spraying dig a hole in the bush and pour down it any makeup spray left in the tank. Wash out the sprayer and pump and pour the washing water down the hole.
6. Store the unused pesticides in a safe place where children cannot enter. Always use the old container,
do not store in a new container such as a drink bottle. Do not store pesticides near food.
4. The pesticide you will buy will often be in a concentrated form so you must follow a proper mixing procedure. Always use a plastic measuring cylinder or the special measure some pesticide factories make so you do not guess amounts of pesticide. Dusts are blown or sprinkled onto plants without using water.
5. Mixing procedure for a liquid pesticide:
1. Fill sprayer tank half way with water.
2. Add measured amount of chemical to sprayer.
3. Fill sprayer tank with water.
4. Shake the sprayer
6. Mixing procedure for a powder pesticide:
1. Put small quantity of water in bucket.
2. Put measured quantity of pesticide powder on top of water, leave till it is thoroughly wetted and then mix into a paste.
3. Add water, then add to half filled knapsack as per instructions for liquid pesticides. If this is not done, some wettable powder will go lumpy and give mixing problems.

6.9.18.2 Dusts
Dusts are best applied either in a proper duster or a tin with a stocking over the end.

6.9.18.3 Withholding period
This is the recommended time between spraying the crop and harvesting the crop so that people will not be made sick by eating the pesticide still on the plants. Make sure that crops which have been sprayed are not harvested within the withholding period. A crop must be washed thoroughly before being eaten.

6.9.18.4 Active constituent
Pesticides are usually a mixture of chemicals. The chemical which kills the pest is called the active constituent (or common chemical name). The other chemicals in the pesticide just make it easier to use and are called the inert ingredients. Some active constituents are inorganic compounds, such as copper oxychloride and some are organic compounds which are compounds of carbon. Thus an organic chloride compound contains a carbon compound and chlorine, and an organic phosphate compound contains a carbon compound and phosphorus The name of the active constituent is always written on the label. Pesticides are made by many different factories in different countries and each factory gives the pesticide its own special name called a trade name, e.g., XXXX or ZZZZ both contain carbaryl. So it is possible or pesticides with different names to contain the same active constituent and be used to kill the same pests.

6.9.18.5 Resistance to pesticides
It often happens that pesticides do not kill all the pests some get sick but still live. These pests may produce offspring which will not be affected by the pesticide to you say that these pests have developed resistance to this pesticide. For this reason it is not wise to always use the same pesticide. Instead the pesticides should be changed from time to time. So when you use all of one pesticide, try using another type.

6.9.18.6 Persistence
Some pesticides and weedicides remain active for a long time, even in the soil. The time they remain active is called "persistence". Pesticides that persist for a long time may be dangerous because their poisonous properties may affect later insects, animals and crops.

6.9.18.7 Surface acting agents
Surface acting agents are chemicals which may already be added to the pesticide or which can be added to the pesticide. They include detergents, soaps, wetting agents, spreaders and stickers. These chemicals spread the pesticide over the plants better and may make them stick to the plants. The label on the pesticide will tell you whether to mix with surface active agents which are sometimes called a surfactant. There are many trade names of surface active agents or you can use any detergent used for washing.

6.9.18.8 Emulsifying agents
An emulsifying agent is a chemical similar to soap which helps oil and water to mix and form an emulsion. When two liquids can mix they are called miscible. Wettable powders (W.P.) are a mixture of an active constituent such as sulfur, an emulsifying agent, and inert materials such as clay. Water is mixed with the wettable powder to make a spray solution. Emulsifiable concentrates (E.C.) are a mixture of active constituent, an emulsifying agent, and oil. Water is mixed with the emulsifiable concentrate (E.C.) to make a spray solution. Emulsifiable concentrates and wettable powders should never be mixed together. The label on the pesticide tell you which other pesticides can be mixed with it.

6.9.18.9 Granules
Synergists. piperonyl butoxide
Granules are very small pieces of rock with pesticides stuck to them. They are usually used when the pesticide has to be put in the soil. Fumigants are poisonous gases used to kill pests in stored crops or soil. They are very dangerous and should not be used in schools. Some Departments of Agriculture use the dangerous poison ethylene dibromide on agricultural products which may carry disease. Synergists are chemicals added to pesticides to make them more poisonous, e.g. piperonyl butoxide makes the insecticide pyrethrum more poisonous. W / V This means weight per volume or the weight of active constituents in a certain volume of pesticide. So 30% W / V emulsifiable concentrate means 30 grams of active constituent in every 100 mL of the emulsifiable concentrate. This may also be written as 300 g / L (grams per litre). W / W. This means weight per weight or the weight of active constituents in a certain weight of pesticide. So a 50% W / W wettable powder means 50 grams of active constituent in every 100 grams of wettable powder. This may also be written as 500 g / kg (grams per kilogram).

6.9.18.10 Pesticide safety
1. Toxic means poisonous to humans.
2. Safe pesticides: Benomyl, Mancozeb, Maneb, Methoxychlor, Quintozene, sulfur, Zineb.
3. Fairly safe pesticides: Harmful, they may cause sore eyes, nose, throat or skin, but there is not much danger if you are careful not to touch or breathe the pesticide.
4. Do not allow students to use Carbaryl, Malathion or Trichlorophon.
5. Dangerous pesticides, toxic.
If these pesticides are breathed in or left on the skin for some time you may get sick and die. Only experienced teachers should use these poisons, e.g. Paraquat, Naled, Rotenone, Nicotine, Dimethoate, Methiocarb. Some pesticides are dangerous if swallowed but not dangerous if left on the skin.

6.9.18.11 Pesticide safety, FIRST AID
If any person gets ill who has been using a pesticide, he should be taken to a doctor or hospital straight away. Tell the doctor or hospital the name of the pesticide used (active constituent) and show him the container. The person who is sick from pesticide should be left to rest, clothing should be changed and the whole body washed. He may need artificial respiration if his breathing stops. If a person has drunk the pesticide he should be given an emetic. This will make him vomit. A good emetic is 2 tablespoons of salt in warm water, then push the handle of the spoon gently on the back of the tongue. He should be kept head down, face down. Give the person Ipecac syrup if it is available. Do not give the person alcohol. Pesticides on the skin should be washed off with plenty of soap and water, keep washing for a long time.

6.9.18.12 Insecticide types - contact, ingestion, systemic
1. Most insecticides kill insects by attacking the nervous system. These chemicals can also harm humans, especially children, so they must be used and stored with great care when used in school food gardening.
2. Insects can take in insecticides in 3 ways:
1. Contact poison
The insecticide touches the body of the insect which then absorbs it.
2. Ingestion or stomach poisons
The insecticide is sprayed onto plants and the insects eat the plants.
3. Systemic poison
The insecticide is sprayed onto plants which absorb it into the sap, sap sucking insects then suck up insecticide in the sap. However, most insecticides are taken in by more than one way. Remember that insecticides may kill the good insects such as bees as well as the bad insects which eat your crops. So use insecticides only when you cannot control the bad insects any other way. If the bad insects are not doing much damage to your crops then do not use insecticides.

6.9.19.0 Sprayers and dusters
1. The chemicals used in agriculture may be applied as granules, dusts, or sprays. Granules are usually put into the soil, dusts are blown onto the crops and so do not need water, but sprays must be made up by mixing the chemical concentrate with water and sometimes a wetting agent. Granules can be spread by hand or you can buy a granule applicator or spreader. The cheapest dusters are the plunger type which look like a bicycle pump. There are also larger and dearer rotary hand dusters. The simplest duster is
made by cutting the bottom out of an opened fish tin and then put it in an old sock.

2. The 3 types of sprayers:
1. Slide action sprayers
They are the cheapest. They are similar to the common fly spray. They contain up to 5 litres of spray. It is very tiring to use them for a long time. They do not control the pressure of the spray. These sprayers can be used in school kitchen gardens.
2. Continuously pumped knapsack sprayers
They are worn on the back or over the shoulder. They should give a continuous spray if you pump them slowly and evenly. They usually contain 10-15 litres of spray. They may be made of brass or plastic. Brass sprayers are tough but heavy. Plastic sprayers are light but can be damaged if dropped or left out in the sun. Plastic knapsack sprayers are the best type to use in school field gardens.
3. Compression type sprayers
After filling these sprayers, they are pumped up to a high pressure. Then they can be used without further pumping. These sprayers are probably too expensive for schools.

3. Care and maintenance for a knapsack sprayer
1. Wash out the sprayer tank, hose and nozzle with clean water.
2. Clean the jet which is the little hole at the end of the nozzle which the spray passes through. Check that it is the right sire for the job. Be very careful not to lose this little jet.
3. Read the instructions on the chemical container carefully. Then measure out the amount of chemical you need for the job.
4. Add clean water to the sprayer until it is half full.
5. Put the measured amount of chemical into the sprayer. Use a special chemical measure or a graduated cylinder to do not guess the amount of chemical concentrate. 6. Wash the chemical measure and put this water into the sprayer. Then fill the sprayer with water.
6. Do not spray in the wind or rain.
7. When spraying walk evenly at about one pace each second. Give each plant an even covering.
8. When finished, dig a hole in the bush and tip out all the unused spray into it. Wash out the sprayer, hose and nozzle and tip all this water down the hole. Remove the hose and nozzle then hang them upside down on the wall inside a lock up shed.
Method
1. Do not use real chemical, use clean water instead!
2. Show the students a knapsack sprayer containing water. Briefly spray some plants with it so that all students know what it is used for.
3. Tell the students that this is a knapsack sprayer which is used to spray plants with chemicals which will kill insect pests and disease. Tell them that they must look after the sprayer very carefully because it is expensive, it is easily broken and it is used to spray poisons.
4. Let the students look closely at the sprayer and pick it up. Ask them the following questions:
1. What is the name of the company which made the sprayer? [XXXX or ZZZZ]
2. Ask students to point to the tank, pump, pump handle, hose, nozzle, jet, harness.
3. How much spray can you put in the tank. [e.g. 13.6 litres or 16 litres]
4. What is the tank made of? [e.g. brass or plastic (polythene)]
5. Demonstrate the first 8 steps of looking after a knapsack sprayer as set out in the manual.
1. Let each student do some spraying. Remember to even pumping, steady walk, wet all of plants evenly (including underside of leaves).
2. The students must NOT spray other people with the spray because the chemicals in sprays are poisons.
3. Demonstrates steps 9 and 10 of looking after a knapsack sprayer.

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

9.7.0 Soil improvement
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:

9.7.1 Soil texture
Soil 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.

9.7.2 Soil 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.

9.7.3 Soil 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.

9.7.4 Soil fertility
Improve the soil fertility by:
4.1 adding plant nutrients as well rotted compost, unless they do not allow compost.
4.2 adding animal manure or water in which animal manure is soaking.
4.3 adding green manure, dig in a legume crop such as cowpea when the flowers are forming.
4.4 adding wood ash, this contains potash (potassium oxide). The ash should be grey white in colour.
4.5 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.
4.6 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.

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, site for planting, approved mulch, composting, and control of pests and diseases. Use only the procedures, agricultural chemicals and insecticides recommended by the local field officer of the Ministry of Agriculture.