School Science Lessons
(Foodgardens1)
2024-12-16
Agriculture
Please send comments to: j.elfick@uq.edu.au
Contents
School Agriculture Projects

1.0 Administration and planning
4.0 Agricultural chemicals
Animal care
Allelopathy
Artichokes
Avocado
Banana
Bees
Beetroot
Breadfruit
Cassava
Chickens
Chillies
Citrus
Cocoa
Coconuts
Composting
Crops
Ducks
Eggplant
Fertilizers
Fruit trees
Fungicides
Gardening
Goats
Herbs
Horticulture
Insecticides
Jackfruit
Legumes
Maize
Mango
Milk
Onion
Olives
Organic farming
Papaya
Pigs
Pineapple
Plant fertilizers
Plant nurseries
Plant protection
5.7.0 Planting
Preface
Pumpkin, cucurbits
Seeds
Soil
Sprouts and microgreens
Sweet potato
Taro
Tomato
Vegetative reproduction
Yams
Wheat
1.0 Administration and planning
Preface
1.1 How to use school food gardens
1.2 Aims and goals
1.3 Organizing school food gardens
1.4 Duties of a supervisor of school food gardens
1.5 Planning school food gardens
1.6 Selecting land
1.7 Choosing crops
1.8 Crop management
1.9 Crop rotation
1.9.1 Rotations for raised beds
1.9.2 Rotations for field crops and perennial crops
1.11 Garden calendar
1.12 When to grow crops
1.13 Clearing land
1.14 Preparing ground
1.15 Three types of gardens
1.16 Records
1.1 How to use school food gardens
1.1.1 Wherever school food gardens are used for the teaching of agriculture.
There is always one big danger - if the gardens are too big, the students may think of school agriculture as just hard work.
This may make the students dislike school agriculture.
The amount of practical work in most of the agriculture teaching notes has been kept small, so it will not make students tired by the hard work.
However, in some places the schools must have big gardens, because they must grow enough food for all the students.
These lessons have been written especially for schools that have to grow food for students.
Because the gardens must be big and there is much work for the students to do, you must think of ways of making the students like this work.
1.1.2 All the students of the school must help in the garden work.
It must not be just the agriculture students that do the work.
1.1.3 Make the working time as short as possible.
It will probably be enough if each student works for one hour each day in the mornings.
You can call this "food growing time" or "school maintenance time".
1.1.4 Allocate each class of students a special garden to work in.
This makes it possible for the students in a class to be proud of their own garden.
1.1.5 Work in the school food gardens should never be used as a punishment.
Teach each class of students to be proud of their work so they can grow some of their own food.
1.1.66 Praise students when they work hard or do a job properly.
1.2 Aims and goals
1.2.1 Following are some aims and goals for school food gardens.
1.2.2 Short-term goals.
Students will understand the different methods used to produce food.
Students can use the different skills needed to produce food.
Students will be interested in taking part in agricultural activities.
1.2.3. Long-term goals.
Students will want to grow some of their own food when living at home in a village or in a town.
Students will want to have a balanced diet both for themselves and for their families.
Students will want to try growing both local and introduced food plants using modern methods.
1.3 Organizing school food gardens
The work of the school food gardens can be done better if there are plans to make the work go well.
Planning:
1.3.1 Food committee
You can form this to help the teacher with his work.
This committee can include the headmaster, the teacher in charge of gardens and one other agriculture teacher, a teacher of home economics and one student from each form.
Having such a committee will help to make all the committee people interested in the gardens.
1.3.2 Involving teachers
Although only the agriculture teachers will do the classroom teaching, all the teachers in the school should take an active part in looking after the gardens and working with the students.
1.3.3 Time for growing time
All the students should do some work in the gardens during a special time each day called "food growing time", or "gardening time" or "school maintenance time".
In some schools all students work in the gardens or one hour each week day and there may be some garden work at the weekends.
1.3.4 Store room.
You must have a store room that can be locked up at the end of the day.
Lock all the tools, equipment and chemicals up in this room.
1.3.5 Stock record book
In the store room keep a stock record book or "inventory book".
In this write a list of all the things kept in the store, as follows:
Table 6.4.5
Item | Number | Date | Remarks
CP-sprayer | 1 | 2/2/00| handle broken 4/1/00
Fungicide | 200g | 2/2/00/ half missing 1/11/00
Spades | 20 | 2/4/00| one missing 2/11/00
The date tells you when the item was first put in the store or when the store was last closed and everything in it counted.
You call this counting a "stock take".
1.3.6 Borrowing book
Every day two students must work in the store.
They must look after everything in the store.
They must also issue tools or other things to the students who are going out to work in the gardens.
However, before they give anything to a student, they must write it in the borrowing book, and the student who is taking it must write his name.
The borrowing book looks like this:
Table 6.4.6
No. items | Item | Student | Date out | Date in | Storekeeper.
1.3.7 Records
The teacher in charge of the gardens should keep records so that the food committee will know:
1. How much food has been harvested and sent to the kitchen
2. The cost of producing this food
3. How much money received from any sales of crops
4. How to plan future food crop production.
1.3.8 Production Record Book
It is used to record the amount of a crop harvested, the amount of the crop sent to the kitchen or sold, and the amount of money received if any of the produce was sold.
In some schools the value of the crop sent to the kitchen is worked out, but no money is paid.
The production Record Book can be kept either as a separate book or as part of the school food gardens diary.
1.3.9 Receipt Book
It is used so you can give a receipt to any person who pays you money.
The carbon paper duplicate is used as a record of how much money you have received.
If you sell any of the produce from the school food gardens always give the buyer a receipt for the amount of money.
1.3.10 Cash Receipts Journal
It is a list of the dates of sales, what you have sold, who you sold it to, receipt numbers, how much you received.
It is usually written at the end of each week by using the information recorded in the Receipt Book.
When you buy something for the school food gardens always get a receipt for the money you pay.
You can keep these receipts on an iron spike.
At the end of each week take the receipts off the spike and write up your Cash Payments Journal that lists the dates of payments, what you have bought and how much you have paid.
If you keep a school food gardens cheque account this information should be on the cheque butts.
The cash receipts journal and cash payments journal can be written in the same exercise book:
Table 6.4.10 Cash Receipts Journal | - | Cash payments Journal
Date | Particulars, e.g. 5 chickens | Receipt No. | Amount, e.g. $10.00 | - l Date | Particulars, e.g. 1 sprayer nozzle | Amount, e.g. $4.95
Date | Total Receipts | - | Total Payments.
1.4 Duties of a supervisor of school food gardens
See diagram: 61.8: Crop diary
Before starting a school food garden, the supervisor of the school food gardens should be able to answer the following 8 questions:
1. What are the aims and goals of the school food garden programme?
Talk about these aims with the food committee.
2, How much labour is needed?
How many hours of work by all the students and staff can be used by you in the gardens?
3. How much money is there to spend on seeds, chemicals and tools?
Who can spend this money?
4. Which record books will be kept and who will keep them?
Is there an inventory book, Production Record book, Receipt book, Cash Receipts and Cash Sales Journal, Savings bank book or cheque book?
Is there a borrowing book kept properly?
Is there any money owed to the school food gardens?
Does the school food gardens account owe any money to anybody or commercial enterprise?
Are there any items that they have not returned to the store?
Are there any items in the store that they should return to their owners?
Has a school food gardens diary been used?
5. What seeds, tools and equipment belong to the school food gardens?
Get some students to help you with stocktaking and making a new inventory.
6. What is the history of the school food garden land? Who owns the land?
Are there any claims from village people to the land or to the produce from it?
Do they dislike any use of the land, e.g. cutting down trees or digging drains?
What crops have been grown on this land before?
7. Is the land described accurately?
If they have already made a map check the details on it or draw a new map.
Show the distance on the map in paces of about 1 metre.
On the map show direction of North, scale of paces, type of vegetation or crops grown, direction of slopes, types of soil, position of trees and rocks, water supply, direction of drainage, fences, gates and buildings.
8. What do the field officers of the Department of Agriculture think about the possible use of the land?
Make an appointment with local agriculture field officers to visit the school and give what help they can give on:
* what to grow,
* supply from them of planting material, chemicals and technical literature,
* help with spraying and ploughing, and receiving produce for sale.
Making Decisions
Students will work together more and learn more if the teacher lets the students do all the activities needed to run the school gardens.
These activities include planning who to do, ordering things, working in the gardens, harvesting and recording how much produce harvested, and eating the produce.
The teacher must always first show how to do a job properly and then step back and watch the students do it.
The first 5 lessons suggest ways to decide with the students' help.
1.5 Planning school food gardens
1. 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.
2. 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:
suitable for school kitchen use and liked by the students, part of a balanced diet, a mixture of local and introduced vegetables.
What advice do agriculture field officers give about the following?
Which part of the land to use and how to use it?
How should you prepare the land for crops?
Which crops are suitable?
Before starting the school vegetables project, answer the following questions:
What amounts of vegetables do you need for the school kitchen?
Who will plant, look after, and harvest the crops?
When will they do it?
How much money can be spent on the gardens?
What tools, equipment, and chemicals are available in the school?
What do you need to buy in the town or get from the Department of Agriculture?
Where will you store tools, equipment, and chemicals?
Who will look after the students and issue them the tools?
Which part of the school land can you use for gardens?
1.6 Selecting land
Gardening, garden products, (Commercial)
The choice of the land to use for school gardens will depend on the following eight points:
1. Which parts of the school are safe from land disputes, claims from who wants part of the crop, safe from stealing by villagers and school boys?
2. What are the best places for raised beds and fields?
The raised beds (1.2 metres x 6 metres) should be near the classrooms, to be convenient for practical agricultural teaching.
For the fields you need a large area of land.
These fields should be no further than 15 minutes from the school.
3. What parts of the school land have the best soil for gardens?
4. What type of vegetation is already growing in the different parts of the school land, e.g. old school 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 tree growing in or near the gardens which can damage crops by shading or root competition?
5. Which parts of the land will need draining, fencing or contouring to prevent soil erosion?
6. How much equipment and planting materials will be available?
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?
8. What total area of land will be needed to achieve the goal set for vegetable production?
The land you select should be approximately square or rectangular.
The students should measure the boundaries in metres and calculate the area of each garden in hectares.
(a) length (metres) x breadth (metres) = area (square metres)
(b) length (metres) x breadth (metres) = area (hectare ha) 10, 000
(c) 100 metres x 100 metres = 10, 000 sq. metres = one ha.
You can mark metres on the classroom floor and let the students practice pacing them.
9. Discuss with students the points to be considered in choosing the land as set out.
You may do this while walking with them about the school grounds.
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 demonstrate to the students how to pace one metre, and calculate the area in hectares pacing around the land?
10. Maps of gardens
The students can do this at the end of the lesson or for homework.
On the map of each garden you should note length, breadth, area, the direction of slope and position of gates and fences.
1.6.2 Calculate how much land you need to plant crops to feed the students, and how many students can be fed for how many days using the crops.
1. Amount of sweet potato to feed to each student per day? Let K = 1.5 kg.
2. Number of students to feed in the school? Let S = 120 students.
3. Amount of sweet potato needed per day = K × S or 1.5 × 120 = 180 kg
4. How many days to feed sweet potato to the students? Let D = 30 days.
5. Total amount of sweet potato needed = K × S × D or 180 × 30 = 5 400 kg
6. What is the expected yield of sweet potato? Let Y = 2 000 kg sweet potato per hectare (per ha).
7. Amount of land needed = K × S × D / Y = 5 400 / 2 000 = 2.7
To feed 120 students, plant about three hectares of sweet potato every month.
1.6.3. If you have five hectares of sweet potato growing, how many days can you feed the students?
1. Area of the crop? Let A = 5 hectares, 5 ha.
2. Expected yield of the crop? Let Y = 2 000 kg per hectare
3. Total expected yield = A × Y or 5 × 2 000 = 10 000 kg sweet potato
4. How many students? Let N = 120.
5. Amount of sweet potato to feed to each student per day? Let K = 1.5 kg
6. The total amount of sweet potato eaten by the students per day = K × N or 180 kg sweet potato per day.
7. The number of days you can expect to feed sweet potato = the total amount of the harvest, divided by the amount they will eat per day =
A × Y / K × 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.
1.6.4 The daily diet of the students should contain about 0.5 kg per student per day of vegetables other than root crops and maize.
Each day 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. eggplant.
4.2 One meal with aibika or pumpkin leaves or local vegetables.
4.3 One meal with banana or coconut.
1.6.5 The land you select should be square or rectangular
The students can measure the boundaries in metres and calculate the area of each garden in hectares.
1. length (metres) × breadth (metres) = area (square metres)
2. length (metres) × breadth (metres) = area (hectares, ha) 10 000
3. 100 metres × 100 metres = 10 000 square metres = 1 ha
4. You can mark metres on the classroom floor and let the students practice pacing them.
1.6.6. Discuss with students the points to be considered in choosing the land.
Do this while walking with the students about the school grounds.
1. 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?
2. Show the students how to pace 1 metre and calculate the area in hectares pacing around the land.
3. Show the land selected for school vegetable gardens
4. 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.
1.7 Choosing crops
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 grow, e.g. coconut, fruit, and the produce of the students' 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, e.g. 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, students' diet should be two parts grain and root crops, one part legumes or meat, one part 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.
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.
Make sure that students use the names of vegetables as in these teaching notes, e.g., sweet potato (not "potato"), aibika, (not "cabbage").
5. 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.
Next to each vegetable write one of the following:
S = grain, starchy food, e.g. maize, or root vegetable, e.g. cassava, yam, taro.
P = legume, protein food (e.g. winged bean, pigeon pea, mung bean, cow pea)
L = leafy vegetable, healthy food (e.g. hibiscus cabbage, pumpkin tips, Chinese cabbage)
F = fruit, healthy food (e.g. papaya, banana)
Tell the students that for a balanced diet they should grow some of each of these types of food.
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 vegetables are needed for the kitchen to be grown next.
1.11 Garden Calendar
When to grow a crop depends on five points:
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/or plant.
3. Harvest period
Most crops planted all at once can be harvested over some weeks.
To make the harvesting period longer, use succession planting - plant a few rows every week.
After completely harvesting a crop, wait at least two weeks before replanting to allow removal of old crops and weeds and allow compost or fertilizer to mix in the soil.
Keeping the land bare of crops is called "bare fallow".
4. Deciding on growing crops depends on:
* Climate, wet season or dry season.
What is the best time for growing a crop?
* Growing period, how long from planting seed to harvest, or from planting seed to transplanting to harvest?
* Harvest period, how long can we keep picking the crop?
* Fallow period, this is when we rest the ground before planting a new crop.
During the fallow period we can clean out all the plants from the last crop, pull out all the weeds, and dig in compost and fertilizer.
1.12 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, planting to harvest
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.
Fallow period is to rest the ground before replanting, clean out all the plants from the last crop, pull out all the weeds, and dig in compost and fertilizer.
3. Harvest Period
You can usually plant crops all at once and later do a complete harvest, but 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
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 chalkboard.
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.
1.9 Crop rotation
It is not easy to follow crop rotation and get the crops harvested when you want them.
You do not want any of your crops to be ready for harvest during the long school holidays.
Time your planting so that crops are growing during that holiday time and are not ready to be harvested, or turned in as green manure.
Use a garden calendar to help you decide when to plant crops.
Before the lesson, work out a crop calendar for using the crops chosen by the teacher and the students.
Use one column for each raised bed or field.
Work backwards from the time of first harvest or planting.
Work forward to end of harvest and fallow period.
The advantages of crop rotation are as follows:
1. Pests and diseases that infect a particular kind of plant or a particular plant family 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, and European potato are all in the same plant family.
2. Different kinds of crops take in different amounts of plant nutrients from the soil.
Legumes add nitrogen plant nutrient to the soil.
3. Different kinds of crops have different depths of roots and affect the way the soil holds together in different ways.
Different food crop families have different effects on the soil and attract different pests and diseases.
So a crop rotation my be based on using a sequence of different food plant families or different kinds of plants.
4. Crop rotation for your school food gardens
See diagram 9.72.1: Mung bean, pigeon pea, winged bean
Raised beds: Chinese cabbage then (2) tomato then (3) winged bean then (4) maize
Fields: sweet potato then (2) cowpea then (3) cassava then (4) mung bean
1.9.1 Rotations for raised beds
3 Beds Rotation
Table 6.6.1
Bed 1 leafy vegetables, then Bed 2 fruiting vegetables, then Bed 3 legumes
Use some space for:
1. Perennial herbs, e.g. rhubarb, garlic, parsley, mint, ginger
2. Local vegetables, e.g. amaranths, purslane, bitter cucumber, comfrey, fern, rungia, pit pit, sugar cane
3. Introduced vegetables: carrots, broccoli, cabbage, cauliflower, celery, basella, kohlrabi, endive, rosella, parsnip, beetroot, zucchini
4. Some vegetables can be grown in running water, e.g. water potato, watercress.
1.9.2 Rotations for field crops and perennial crops
Bed 1 leafy vegetables, then Bed 2 fruiting vegetables, then Bed 3 legumes, then Bed 3 root crop or grain
Table 6.6.2.1 Perennial crops
Avocado, granadilla, oil palm, banana, guava, papaya, breadfruit, jackfruit, pineapple, citrus, litchi, passionfruit, coconut, Malay apple, custard apple, mango, rambutan, five corners, mangosteen, sago palm, sugar cane.
1.8 Crop management
Care of the crop: Keep soil cultivated between plants, well drained and free of weeds.
This will allow the crop to grow strongly and not lose any water and plant nutrients to weeds.
Use mulch to protect the soil, but do not let it touch the plant stems, because some disease may be in the mulch.
Add some compost or artificial fertilizer to provide plant nutrients to keep the crop healthy.
Interplanting can help plants to help each other so use a mixture of different kinds of plants in a garden, for example:
| sweet potato | maize | climbing bean | maize | pumpkin | maize | sweet potato |
If the same kinds of plants are separated from each other by other kinds of plants, it is harder for pests and disease to spread from plant to plant.
Also, some plants can help each other by shading weeds or repelling insects, e.g. marigolds will protect other plants from nematode worms.
Raphanus sativus, radish, is a pungent companion plant to many species, but not hyssop, Hyssopus officinalis.
Control by hand: Insects such as caterpillars, diseased plants and parts of plants can be removed by hand and burnt.
Crops should be looked at every day for signs of pests and disease.
Garden hygiene: Do not leave diseased plants in the garden - pull them all out and burn them.
Also look at compost heaps and mulch for signs of insects that attack plants, e.g. Rhinoceros Beetle, mole crickets.
1.13 Clearing land
1.13.1 Clearing land is mainly hard work and you must try to make sure that this work is not so hard that the students hate agriculture.
Most of this work should be done during school gardening time or school maintenance time.
You can make hard work more interesting by:
1. Always praise the best efforts rather than criticizing the lazy or careless work.
2. Have a definite well-organized work period, e.g. "all students will cut bush between 3.00 pm and 4.00 pm working with me".
3. Set a realistic goal for each work period, developing competition between classes.
4. Do not let boys compete against girls.
5. Do not do all the interesting part of the work yourself.
6. Train groups of students to work by themselves with a student leader.
Give this lesson before the students clear the land so they know why they are doing this work.
To prepare land for vegetable gardens it must be cleared, drained and fenced.
Reasons for clearing:
1. To stop competition for plant foods from other plants called weeds,
2. To allow cultivation, no logs, trees, roots or stones,
3. To stop shading of the crop from trees.
1.13.3. Land should be cleared twice before planting:
1. First clearing: cut down bushes and trees, remove logs, roots, stones and weeds.
2. Second clearing: 3 weeks later pull out all new weeds.
Put all weeds on the compost heap.
1.13.4 Reasons for draining:
1. To allow air to get into the soil for the roots to breathe,
2. To stop diseases living in the soil that can attack the roots and stem base of crop plants.
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.
1.13.5 Reason for fencing:
1. To keep pigs and other animals out.
2. To keep people out.
1.13.6 Protect bare soil
After clearing 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 by 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.
1.13.7 Stop water erosion
1. Use good drains with grass growing in them,
2. Put ridges and beds across a slope and not up and down it.
1.14 Preparing ground
See diagram 6.0: Preparing ground
Reasons for preparing the ground:
1 To loosen the soil so roots can grow easily,
2 To make a fine even seed bed so seeds will germinate easily and quickly,
3 To control weeds and insect pests by digging them up,
4 To improve the soil by mixing in dead plants and compost which will increase the plant nutrients in the soil and make the soil easier to dig,
5 To form the soil into raised beds or ridges so it is ready for planting.
Digging
1. Dig deeply with a garden fork and the rake the soil from different angles to make a soil with a fine tilth.
2. 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 garden beds and ridges run in a north-south direction, all the plants in one row get the same amount of light.
4. Clay soils needs deep digging with the addition of gypsum and compost.
The steps in preparing ground are as follows:
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:
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. Use rakes and hoes to make the soil fine and even.
4. Raised beds should be 1.5 metres × 6 metres × 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.
1.15 The 3 types of gardens: Kitchen gardens, Field gardens, Perennial tree crop gardens
1. Kitchen gardens are near the kitchen and classroom.
The soil is dug to form raised beds.
Each bed may be 6. 0 x 1. 2 metres in area and it is 15 cm higher than the ground.
It is separated from the next bed by pathways 50 cm wide.
These gardens are used to grow vegetables that can be picked fresh:
* Fruiting vegetables, e.g. tomatoes,
* Leafy vegetables, e.g. Chinese cabbage and hibiscus cabbage.
Part of the kitchen gardens may be used for perennial vegetables that grow a long time, e.g. mint, rhubarb, parsley.
2. Field gardens are not near the kitchen.
They are large areas of land used for growing food crops, e.g. root crops, e.g. kumara, cassava or yams, and also for growing maize and legumes, e.g. beans, cow peas, peanuts.
These gardens are for annual crops.
3, Perennial tree crop gardens are separate gardens to grow long lasting or perennial crops, e.g. papaya, bananas, chillies, hibiscus cabbage, pineapples
coconuts and other tree crops.
4. The three main methods of cultivation are as follows: raised beds, ridges, mounds.
1.6.12 Calculate food crop production
Growing food for a balanced diet
If each student eats 3 kg of food each day then the following mixture of the 5 types of food would provide a balanced diet:
Type of Food, Amount eaten, g
1. Starches energy food, Potato (sweet potato) yam, cassava, taro, banana, maize or rice or wheat meal
2. Fats and oils, high energy foods, 30 g, Coconut oil, palm oil, peanut oil, beef or pork fat, dripping (oil in tinned fish)
3. Protein, bodybuilding foods, 150 g, Meat, fish, shellfish, bean seeds, eggs, milk (tinned meat, tinned fish)
4. Vegetables, health foods, 100 g, Aibika, pumpkin tips, amaranths, taro leaves, bean pods, leafy vegetables, cooked green papaya
5. Fruits, health foods, 200 g, Pineapple, papaya, banana, melon, pumpkin, eggplant, lime, orange, guava, chillies,
6. Coconut, which contains oil and sugars
Total amount of food, 2 980 g + 1 coconut
The school food garden should provide all these types of food and a variety of each type.
The students should not be fed the same mixture of food every day.
Expected yields
Banana, If planted 33 metres = 1 090 plants / hectare
If each plant yields 2 bunches / year and each bunch weight 23 kg, then the yield / hectare / year = 50 tonnes / hectare / year
Bean, Up to 37 tonnes / hectare in 3 months
Cassava (tapioca) 12.5 tonnes / hectare in 6 months = 25 tonnes / hectare / year
Coconuts, If need one coconut for each student for each day, and if each palm yields 50 nuts / palm / year,
If planted 88 metres = 192 palms / hectare
If planted 77 metres = 196 palms / hectare
Yields 19650 = 9 800 nuts / year
If 270 days in a school year, 1 ha yields 9 800 / 270 = 36
Eggplant (aubergine) At planting distance of 9060 cm, yields 27 tonnes / hectare in 4 months
Aibika, At planting distance of 2.52.5 metres = 1 600 bushes / hectare
If pick 0.5 kg from each bush every 3 weeks, then yield / bush / year = 0.517 = 8.5 kg / bush year yield / hectare / year = 13.6 tonnes / hectare / year
Papaya, If planted 88 metres = 140 plants / hectare (18 males and 122 females) yield = 7.5 tonnes / hectare in second year of bearing
Peanut, 1.1 tonnes / hectare in 5 months
Pineapple, If planted 6060 cm = 19 tonnes / hectare / year
Pumpkin, At planting distance of 1.51.5 metres yields 37 tonnes / hectare in 5 months.
Sweet Potato, 12.5 tonnes / hectare in 6 months × 2 = 25 tonnes / hectare/ year
Yams, 5 tonnes / hectare / year, 10 months to maturity.
1.16 Records
Preparation
1. Record books, e.g. the School Food Gardens Diary, Production Record Book and Receipt Book should be written up each days.
2. The Cash Receipts Journal and Cash Payments Journal should be written up at the end of each week.
3. At certain times read all these records again so that you can remember and think about all the information about each crop and about the gardens.
Read all these records again to improve your knowledge about the school food gardens and to assist in further planning.
4.0 Collect 3 type of information, Yields, Profits, Comparative yields
4.1 Yields
Get this information from your Productions Record Book.
The information you will need are as follows:
1. Yield of each crop in kilograms per hectare (kg per ha) (or yield on a smaller area).
2. Yields of kitchen gardens in kilograms per garden
3. Yields of trial gardens, e.g. single cropping (potato) and intercropping (potato and maize) and also crops with fertilizer and without fertilizer.
4. Yield of each crop as income (returns) per hectare.
How much money was received for each hectare or smaller area of the crop or for each kitchen garden?
5. Yield of each crop as kilograms per hectare divided by total number of student hours worked to produce that yield.
6. Yield of each crop as income per hectare divided by the total number of student. hours worked to produce that yield.
You can calculate yields in other ways that may be useful for further planning, e.g. yields as the number of school meals per hectare.
Yield per hectare of all the school food gardens together for one year.
This is called the productivity of the school food gardens.
4.2 Profits
The second type of information to be collected is on profits.
1. "Returns" refers to the money you receive for a crop.
2. "Costs" refers to the money you pay for things to produce the crop.
Costs are divided into production costs and establishment costs.
3. "Production costs" refers to the costs of items used in producing a crop, e.g. seeds, fertilizer, tractor hire and cost of paid labour.
Production costs include cost of planting material bought, cost of tractor hire, cost of fertilizer used, cost of insecticide used.
4. "Establishment costs" refers to the cost of items needed to produce the crop, but which last a long time and can be used to produce other crops, e.g. nursery, tools, fencing materials, buildings.
Assume that items of establishment costs will last for 5 years.
So for any one year, divide the establishment costs by 5.
Profit is the amount of money left when you take costs away from returns.
Profit = Returns to Production Costs to Establishment cost / 5
Try to calculate the profit for each agricultural project in your school food garden.
This is fairly easy to do for a project, e.g. a chicken project, because the materials cannot usually be used for anything else.
However, this is not so easy if you want to find the profit of separate crops.
For example, how do you find the establishment cost to a potato project of a fence dividing it from other crops?
How do you find the establishment cost of tools used on many projects and on general school maintenance?
These costs can be found when you work out the profit of all the school food gardens over a year, but it is best to ignore them when finding the profit of individual crops, unless only that crop uses the item.
At the end of the term or school year you can calculate the profit of all the school food gardens together.
In this case you can include items, e.g. cost of fences, tools, machinery and buildings in the establishment costs.
Be careful not to compare the profits from school food garden as a whole with those of real farms, because there are important differences between the two, so you cannot find the profit in the same way.
A farm will have more costs than a school e.g. taxation, rent, cost of labour.
You can borrow things for use in the school food garden from the rest of the school, which the farmer would have to pay for e.g. cost of electricity, use of school tractor, use of measuring tape from the maths department.
In a school you have lots of free labour for short periods of time, but the labour is not efficient, because you are using students.
In a farm you would employ fewer labourers for whole days and the labour is more efficient.
School projects are often too small to make a real profit.
The cost of fencing alone may make small cattle or chicken projects unprofitable.
Not many schools can use a tractor enough to make this purchase lead to profitable projects.
4.3 Comparative yields
Compare the yield of the crops so that you can decide whether it is better to grow potato or cassava, or is it better to grow wing bean or cowpea?
Calculate and compare yields as:
1. Kilograms per hectare (kg / ha),
2. Kilograms per hectare per student hour worked,
3. Meals per hectare or meals per kitchen garden.
With the above information and a knowledge of rotations decide which crops to plant first.
1. Explain the meaning of returns, costs and profit.
Tell the students why the profit of a vegetable project is calculated.
2. Fill in this table using your records:
2.1 Returns $
2.2 Production costs $
2.3 Seeds $
2.4 Fertilizer $
3. Establishment costs $
If you assume that the items will last 5 years then for any one year divide the establishment costs by 5.
3.1. nursery $
3.2 Miscellaneous, e.g. plastic bags $
4. The students can now calculate the profit of this project.
Profit = [Returns| Production costs | (Establishment costs / 5)]
5. Ask the students to suggest what can be done with the profits.
They can be used to buy things you need, e.g. food and clothing.
They can also be used to buy things you need for new projects, e.g. buy more seed and fertilizer.
This is called investing.
Tell them that it is not good to spend all the profits on things you need.
Some of the profits should be kept for investing in new projects.
5.7.0 Planting
5.7.1 Planting pots
5.7.2 Planting pots
5.7.3 Planting bare rooted trees
5.7.4 Planting guide
5.7.5 Planting guide from the Moon
5.7.1 Planting
The problem of poor germination is usually caused by sowing seeds too deeply, or over-watering or under-watering.
If the seed is planted too deeply, the tiny developing plant exhausts the food supply in the endosperm before the shoot and leaves have broken through and it dies.
The general rule is to plant a seed at a depth that equals twice its width.
Water newly-sown seeds with a mixture of one fifth of a teaspoon of Epsom salts in a litre of water to aid the germination process.
The magnesium in the salts will help stimulate the enzymes that make the food in the endosperm more readily available to the young seedling.
Small seeds should be only lightly covered with soil, but larger seeds will be planted at a greater depth.
The surface of the soil dries out more quickly than it does a few millimetres deeper.
Small seeds that are surface-sown should be kept moist after planting.
Larger seeds should be given a good soaking at planting time and then watered again only after they break through the ground.
If you water the larger seeds too much, they will rot in the moist soil.
The seed of many vegetables and flowering annuals are F1 hybrids, where the plant breeders have combined two strains each with desirable characteristics.
However, F1 hybrids usually do not set seed or the seeds are not viable.
Experiment
Plant tomao seeds
To select tomato seed for planting, squeeze the pulp and the seeds on absorbent paper, e.g. a paper towel, and spread it evenly over the paper.
Remove as much pulp as possible and lay the remainder in the sun for two weeks to dry the germination inhibiting enzymes.
Lay the paper towel with seeds uppermost on seed raising mix and lightly cover with fine seed mix.
Water lightly until the seedlings emerge.
5.7.2 Planting pots
Cultivate soil before planting.
Dig hole twice the width of the container.
Remove plant from the container and place into the hole so the soil level is the same as the surrounding ground.
Fill hole firmly and water in well even if the soil is moist.
5.7.3 Planting bare rooted plants
Based on "Bare Rooted Plants", Gardening Australia program, Australian Broadcasting Corporation, Broadcast Sat 30 Jul 2005 at 12:00am.
Deciduous trees can be purchased as potted plants or bare rooted plants.
Bare-rooted plants are sold in winter when they are dormant, because this gives them the best chance of being replanted or tranplanted successfully.
During winter, trees and shrubs that have been field grown are dug up when they're dormant, and sold, ready for planting.
You can buy nearly all deciduous plants bare rooted - everything from fruit trees to roses and ornamentals.
Bare rooted plants are grown from seed in a plant nursery, then budded or grafted and then shaped for planting in the garden.
It takes about two years to produce most of the trees.
In Australia, bare-rooted plants are available in winter - June, July and August.
After August it's too late because they start to shoot and then transplanting becomes a problem.
Plant the tree soon after receipt and don't leave it lying in the sun while you are are digging.
Prune the tree after planting, because when the trees are dug, the roots are pruned, and for a balanced tree the tops should be pruned to match the root size.
Cut branches to about 30 centimetres from the main trunk, and to a bud.
To encourage a nice branching habit, remove the leader.
When you're selecting a bare rooted plant, try to ensure there is no obvious physical damage and look for a good, even branch structure.
If it's grafted, or budded, watch for any growth emerging from the base, just remove it because that's the root stock reappearing.
Before planting, remove any diseased, or even damaged, roots.
Dig a hole with a wide diameter, but at a depth so you can plant the tree at the same level as when it was originally in the ground.
Look closely at the base of the stem and notice any slight change in colour - that is where it was in the ground.
The bud or graft should be is about 10 centimetres above the ground.
Spread the roots out in a natural position and mound a pile of soil at the base to help support the root system.
Then backfill with good soil and wiggle the tree as you go.
Add water to remove any air pockets.
Loosely stake the tree until it is established.
Do not fertilise until the tree starts growing in spring.
Bare root fruit trees Daleys Fruit Trees
5.7.4 Planting guide
Crop | Planting depth (cm) | How planted | Distance between plants | Distance between rows | Time to harvest (weeks)
Amaranthus, sprinkle, direct planting, thin to 15 cm between plants, 15 cm between rows, 6 weeks to harvest
Banana, 45 cm deep, suckers, 200 cm between plants, 200 cm between rows, 40 weeks to harvest
Basella, 5 cm deep, direct planting, thin to 30 cm between plants, 30 cm between rows, 5 weeks to harvest
Bean, 5 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 10 weeks to harvest
Beetroot, 2 cm deep, direct planting, thin to 15 cm between plants, 30 cm between rows, 10 weeks to harvest
Broccoli, nursery, 45 cm between plants, 45 cm between rows, 14 weeks to harvest
Cabbage, nursery, 45 cm between plants, 60 cm between rows, 10 weeks to harvest
Capsicum, nursery, 45 cm between plants, 45 cm between rows, 10 weeks to harvest
Carrot, 1 cm deep, direct planting, thin to 5 cm between plants, 30 cm between rows, 12 weeks to harvest
Cassava, 10 cm deep, cuttings, 100 cm between plants, 100 cm between rows, 30 weeks to harvest
Cauliflower, nursery, 45 cm between plants, 60 cm between rows, 20 weeks to harvest
Celery, nursery, 15 cm between plants, 60 cm between rows, 20 weeks to harvest
Chinese cabbage, nursery, 30 cm between plants, 45 cm between rows, 10 weeks to harvest
Chilli, 10 cm deep, nursery, 75 cm between plants, 150 cm between rows, 20 weeks to harvest
Choko, 5 cm deep, fruit, 30 cm between plants, 100 cm between rows, 12 weeks to harvest
Comfrey, 20 cm deep, cuttings, 75 cm between plants, 100 cm between rows, 50 weeks to harvest
Cowpea, 5 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 10 weeks to harvest
Cucumber, 2 cm deep, thin to 30 cm between plants, 60 cm between rows, 10 weeks to harvest
Eggplant, nursery, 60 cm between plants, 60 cm between rows, 12 weeks to harvest
Ginger, 5 cm deep, rhizome, 15 cm between plants, 45 cm between rows, 30 weeks to harvest
Haricot bean, 5 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 10 weeks to harvest
Hibiscus cabbage, 10 cm deep, cuttings 60 cm between plants, 100 cm between rows, 10 weeks to harvest
Kohlrabi, nursery, 15 cm between plants, 45 cm between rows, 10 weeks to harvest
Lettuce, nursery, 30 cm between plants, 30 cm between rows, 8 weeks to harvest
Maize, 2 cm deep, direct planting, 15 cm between plants, 60 cm between rows, 15 weeks to harvest
Marrow, 5 cm deep, direct planting, 100 cm between plants, 200 cm between rows, 12 weeks to harvest
Melon, 5 cm deep, direct planting, 100 cm between plants, 200 cm between rows, 12 weeks to harvest
Mung bean, 2 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 9 weeks to harvest
Okra, 5 cm deep, direct planting, 30 cm between plants, 75 cm between rows, 10 weeks to harvest
Onion, 5 cm deep, direct planting, thin to 10 cm between plants, 30 cm between rows, 15 weeks to harvest
Parsley, 1 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 12 weeks to harvest
Parsnip, 1 cm deep, direct planting, 15 cm between plants, 45 cm between rows, 20 weeks to harvest
Papaya, transplant 200 cm between plants, 200 cm between rows, 16 weeks to harvest
Peanut, 2 cm deep, direct planting, 30 cm between plants, 30 cm between rows, 15 weeks to harvest
Peas, 5 cm deep, direct planting, 5 cm between plants, 45 cm between rows, 10 weeks to harvest
Pigeon pea, 5 cm deep, direct planting, 60 cm between plants, 100 cm between rows, 24 weeks to harvest
Pineapple, shoots / slips, 30 cm between plants, 60 cm between rows, 60 weeks to harvest
Pit pit, Saccharum, 20 cm deep, cuttings 100 cm between plants, 100 cm between rows, 8 weeks to harvest
Pumpkin, 2 cm deep, direct planting, 100 cm between plants, 200 cm between rows, 15 weeks to harvest
Purslane, sprinkle direct planting, 15 cm between plants, 45 cm between rows, 6 weeks to harvest
Radish, transplant, 25 cm between plants, 25 cm between rows, 16 weeks to harvest
Rhubarb, 2 cm deep, seed / crowns 45 cm between plants, 45 cm between rows, 5 weeks to harvest
Silver beet, nursery, 15 cm between plants, 30 cm between rows, 10 weeks to harvest
Snake bean, 5 cm deep, direct planting, 15 cm between plants, 100 cm between rows, 8 weeks to harvest
Snake gourd, 5 cm deep, direct planting, 30 cm between plants, 100 cm between rows, 8 weeks to harvest
Sorghum, direct planting, 15 cm between plants, 30 cm between rows, 15 weeks to harvest
Soya bean, direct planting, 15 cm between plants, 60 cm between rows, 12 weeks to harvest
Spinach, nursery, 15 cm between plants, 30 cm between rows, 8 weeks to harvest
Spring onion, 10 cm deep, direct planting, thin to 5 cm between plants, 30 cm between rows, 12 weeks to harvest
Sugar cane, cuttings, 100 cm between plants, 150 cm between rows, 50 weeks to harvest
Sunflower, 5 cm deep, direct planting, 45 cm between plants, 45 cm between rows, 16 weeks to harvest
Sweet potato 10 cm deep, cuttings 45 cm between plants, 75 cm between rows, 14 weeks to harvest
Tannia, 10 cm deep, corms, 100 cm between plants, 100 cm between rows, 120 weeks to harvest
Taro, 20 cm deep, tops, tubers, 60 cm between plants, 100 cm between rows, 80 weeks to harvest
Tomato, nursery, 60 cm between plants, 60 cm between rows, 14 weeks to harvest
Turmeric, 5 cm deep, rhizome, 15 cm between plants, 30 cm between rows, 35 weeks to harvest
Watercress, 2 cm deep, root cuttings, 15 cm between plants, 15 cm between rows, 10 weeks to harvest
Winged bean, 2 cm deep, direct planting, 15 cm between plants, 15 cm between rows, 12 weeks to harvest
Yam, 10 cm deep, tuber cuttings, 100 cm between plants, 100 cm between rows, 40 weeks to harvest
Zucchini, 5 cm deep, direct planting, 100 cm between plants, 100 cm between rows, 8 weeks to harvest.
5.7.5 Planting guide from the Moon
The Moon's gravitational pull affects the movement of water on the Earth.
Tides are at their fullest during a full moon and their lowest during a new moon.
The moon also affects the surface tension of moisture in the soil and the flow of water through plants.
Sap moves more vigorously during the waxing phase as the moon grows to full, and slows down as the moon wanes towards the new moon.
1st Quarter Phase: The New Moon (dark moon) is increasing in light, a waxing moon.
The first quarter phase starts 12 hours after the exact New Moon and finishes 12 hours before the First quarter moon.
Water in the Earth is starting to be drawn up at this time, the tides start increasing in height, and moisture is increasing in the soil.
Increased sap flow produces new growth more quickly.
The best time for planting leafy annuals such as basil, parsley, coriander, dill and rocket, applying liquid fertilisers, pruning and grafting.
2nd Quarter Phase: The moon is still waxing, now showing more than half of its visible surface as light.
The 2nd quarter phase starts 12 hours after the first quarter moon and runs through to 12 hours before the exact full moon.
When closer to the full moon, the pull on the earth is increasing and the tides are reaching much higher levels.
The moisture in the soil is increasing and the sap in the plants is increasing.
The best time to plant fruiting/flowering annuals, e.g. tomatoes, beans, chillies, red clover, chamomile, and applying liquid fertilisers, pruning and grafting.
3rd Quarter Phase: The full moon has passed and will now decrease in light on its surface, a waning moon.
It runs from 12 hours after the exact full moon until 12 hours before the third quarter moon.
The tides have turned and will now start to decrease in height.
There is still moisture in the earth and the sap is still high although the flow is drawing down.
This focusses the energy towards the roots, which is more suited to root crops and perennials, plants that live longer than two years.
The best time to plant root vegetables and perennials such as beetroot, carrots, onions, licorice, turmeric, ginger, rosemary, sage, thyme and oregano.
Take cuttings and divide plants, apply solid fertiliser and harvest for storage.
4th Quarter Phase: More than half of the visible surface of the moon is now in darkness.
Starts 12 hours after the third quarter moon and runs through to 12 hours before the exact new moon The tides will soon be at their lowest and the sap in plants has slowed.
This phase is viewed as low in vitality and planting is not recommended now, so do not do any planting during this time.
The best time to do mowing, weeding, composting, mulching and insect control, apply solid fertilisers and prune to restrain growth.
5.7.6 Allelopathy
Getting to know Allelopathy
Phytochemicals are chemicals produced by plants.
Many people think of phytochemicals as the chemicals that can affect our health, but are not essential nutrients.
They are thinking about the carotenoids, flavonoids, isothionates, phytosterols and the many other chemicals which are said to improve our diet and help us get through the day.
But you think about phytosterols from the point of view of a plant.
A plant does not manufacture phytochemicals to improve its own health or our health.
Plants use phytochemicals to protect themselves from danger.
A plant goes to all the trouble and use of resources to manufacture complex chemicals to protect itself from competition from other plants, hungry herbivores and nasty microbial attack.
In fact, plants have found ways to produce biochemicals that influence the germination, growth, survival, and reproduction of other organisms to keep themselves safe from harm.
This interference mechanism is called allelopathy.
The term allelopathy was invented by Austrian researcher Hans Molish, (1856-1937), from the Greek alleon mutual, and pathos harm, i.e. "mutual suffering".
The name refers to the chemicals washed out into the soil from fallen leaves of a defending plant.
He was friends with Gregor Johann Mendel, the founder of genetics, who gave us Mendels' Laws.
He was told to re-examine the publications of Charles Darwin, author of 'The Origin of Species', published 1859.
Hans Molish knew that what he called allelopathy had long been known.
In 26 BCE, the Roman author Varro, wrote about the harmful effects of walnut trees on nearby growing species.
Varo did not know that he was writing about the phenolic organic compound juglone, C10H6O3, secreted by the roots of the black walnut (Juglans nigra), which interferes with understory plants.
In 1606 CE, William Shakespeare, in his play 'Macbeth', wrote about the interest in allelopathy of 3 witches:
"Eye of newt and toe of frog,
Wool of bat and tongue of dog ...
Double double toil and trouble:
Fire burn and cauldron bubble".
In 1805 CE, Swiss botanist, Augustin Pyramane de Candole, wrote about the effects of root excretions.
Was he on to something important?
Since then, not much is yet known about the interactions of chemicals excreted by plant roots and what is going on in the soil.
Who cares?
Most people are aware of the effects of too much of the amine capsaicin, C18H27NO3, from chillies.
This chemical may restrict ingestion from herbivores and could be considered as a form of aerial allelopathy.
Many of the modern drugs used for medicine and illicit purposes are manufactured by plants as a defence against being eaten by herbivores.
Leaving aside aerial allelopathy, we have two forms of soil allelopathy.
1. Leaves from the defensive plant fall down, rot, and leave active allelochemicals in the soil below the plant.
2. The roots of the defensive plant actively secrete allelopathic chemicals into the soil.
For example, the extracts, essential oil, leachates, residues, and rhizosphere soil of Lantana camara suppress the germination and growth of other plant species.
Several allelochemicals, such as phenolic compounds, sesquiterpenes, triterpenes, and a flavonoid, have been identified.
They have been released into the rhizosphere soil under the canopy during the decomposition residues and from the living plant parts of Lantana camara.
The released allelochemicals suppress the regeneration process of indigenous plant species by decreasing their germination and seedling growth and increasing their mortality.
Recent researchers in plant-derived allelochemicals have suggested that they could be used for natural weed killers and in the selection of crops for mixed interplanting and crop rotations.
Use of the natural allelochemicals would give us biological weed control and we could get rid of the chemical weedicides, e.g. glyphosate, C3H8NO5P.
Researchers knew that Greek oregano, (Origanum vulgare ssp. hirtum), and rosemary, (Rosmarinus officinalis), were allelopathic plants.
So they used their essential oils for control of weeds and volunteer wheat species, and so reducing environmental damage and health hazards from chemical inputs.
Besides offering excellent prospects as herbicides, the researchers thought that allelochemicals could be used for counteracting weedicide resistance.
Recently, glyphosate resistance has been discovered in Victorian pasture grasses.
The recent new interest in native Australian food plants, formerly call "bushfoods", has lead to research about the history of aboriginals using native plants for medicinal purposes.
The Australian native bottlebrush (Callistemon citrinus) has been used to develop a broad-spectrum maize weed herbicide, Callisto®, now sold as Syngenta 2005.
Callisto® has more effective weed control than existing herbicides, with excellent crop safety and a good environmental profile (Syngenta 2005).
Also, Stinking gidgee wattle (Acacia cambagei), which grows in north-west Queensland, has almost no other species growing nearby.
This occurs, not because of its unpleasant smell after rain, but because it is excreting allelochemicals into the soil.
These allelochemicals could be used to control pastoral weed, e. g. annual ryegrass, (Lolium rigidum).
The giant ragweed, (Ambrosia trifida), is an allelopathic weed which reduces productivity of arable lands.
Perhaps there are lots of useful allelochemicals in the Queensland soil, waiting for us to find them! Allelopathy is the basis of some of the practices used in companion planting, whereby some plants like each other.
Some people call allelopathy: "non-companion planting"!, Extracts from oregano roots and shoots were said to have allelopathic potential, based on bioassays using oat (Avena sativa) and the common duckweed (Lemna minor), testing fresh weight and radicle length.
Nowadays, State Departments of Agriculture are issuing allelopathy warning to farmers.
From Western Australia Department of Primary Industries and Regional Development: "Uncontrolled heavy weed growth during the summer fallow period in can reduce the yield of the subsequent crop by reducing crop emergence due to the physical and/or allelopathic interference at seeding time".
From Brisbane City Council, Weed Identification Tool: "Golden rod, (Solidago altissima), Asteraceae, weedy plant is a strong competitor in part to alleleopathic compounds, (chemicals that suppress the growth of other plants), it produces, and in the garden and grasslands, it can become weedy.
Some allelopathic weeds from "Weeds Australia".
Creeping Yellowcress, (Rorippa sylvestris), contains the anthocyanin hirsutin, C18H17O7, in its roots, which inhibits germination and growth of some crops.
Spotted Knapweed, (Centaurea stoebe subsp. australis), exudes a toxin from its roots that inhibits the growth and germination of surrounding vegetation by chemical suppression of competitors, known as allelopathy.
Tree-of-heaven, (Ailanthus altissimaIt), inhibits post-disturbance succession by other plants by creating a relatively toxic soil environment.
Indian toothcup, (Rotala indica), is a serious weed of rice in Afghanistan, Japan, Korea, Philippines, Taiwan and US, but not in Australia.
Certain Indian toothcup plants, or extracts from them, are able to suppress the growth of weeds in rice paddies, through allelopathy by the release of chemicals.
There is no agreed list of allelopathic plants, but the following are often mentioned:
black mustard.
cabbage, broccoli, rapeseed.
Wild aster (Aster subulatus), maize, French marigold (Tagetes patula), Garlic mustard weed (Alliaria petiolata) Johnson grass (Sorghhum halepense).
Allelochemicals not only suppress weeds, but also promote underground microbial activities.
Crop cultivars with allelopathic potentials can be grown to suppress weeds under field conditions.
Further, several types of allelopathic plants can be intercropped with other crops to smother weeds.
The common duckweed, Lemna minor, changes the water chemistry to favour harmful algae and bacteria which attack other floating plants.
How do you use or prevent allelopathy in your herb garden?
1. Good crop hygiene
After harvest, remove all crop residues, including all the roots, and compost them or use them as mulch under fruit trees to suppress weed growth.
2. Control allelopathic weeds
Do not let Couch Grass, quackgrass (Agropyron repens), Yellow nutgrass, Mullumbimby couch. (Cyperus esculentus), Ragweed, (Ambrosia artemisiifolia) etc. grow in or near the garden beds.
3. Use crop rotation to prevent the build up of allelopathic chemicals.
After 30 years of its successful publication, in 2023 the International Allelopathy Journal changed its publications policy.
It had defined allelopathy as the in-vivo interactions between plants, microbes and animals and had published articles mainly related to agriculture and biological sciences.
Since then, it expanded its scope to include articles related to use of plant chemicals in human and animal health.
It argued: "With increased resistance to prevalent antibiotics, there is now greater interest in testing new plant chemicals, which have pharmaceutical properties to control a variety of human diseases such as cancer and diabetes.
".
It invited researchers to submit manuscripts related to the influence of plant chemicals on human and animal health.
However the journal is still publishing articles, such as:
"Allelopathic effects of Cassia fistula L on germination and seedlings growth of Raphanus sativus L".
In a study to evaluate the allelopathic effects of radish, (Raphanus sativus L.) on bread wheat, (Triticum aesitivum L.), wild oat (Avena fatua) and wild barley, (Hordeum spontaneum). in 5 kg pots, all plant species were shown to be sensitive to radish root extract.
It suppress seed germination, radicle growth, seedling emergence, and seedling growth.
At the cellular level, it caused oxidative stress, protein modifications, cell damage and cell death.
However, allelopathy is not the simple answer to why few or no plants grow near another plant.
Experiments such as above can show that species A suppresses species B, because species A produces a powerful toxic chemical which suppresses species B.
But accumulation of a lot correlative evidence is needed to eliminate all other potential mechanisms.
For example, allelopathy may be effective only in areas of low rainfall where germination-inhibiting chemicals can accumulate in the soil around the defending plants and not be washed away.
The defensive plant may dry out the upper layers of the soil, so seeds cannot germinate.
There is no quick answer as to whether spaces around plants are caused by alleopathy.
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.