Cover Image
close this book Forestry training manual for the Africa region
View the document Acknowledgements
View the document Trainee guidelines
Open this folder and view contents Training program overview
Open this folder and view contents Conducting the training program
Open this folder and view contents Presenting the sessions
View the document Words about transition
View the document Session 1 : Welcome, expectations, and evaluation criteria
View the document Session 2 : Special projects
View the document Session 3 : The forests of the world, peace corps' forestry goals, the individual volunteer's role
View the document Session 4 : Record keeping - group process
View the document Session 5 : Video tapes
View the document Session 6 : Agro-forestry data collection
View the document Session 7 : Feedback
View the document Session 8 : Flowers, seeds, the beginning
View the document Session 9 : Nutrition
View the document Session 10 : Non-verbal communication
View the document Session 11 : Germination
View the document Session 12 : Coping skills
View the document Session 13 : Basic site selection, planning & layout of a nursery
View the document Session 14 : Review of trainees' nursery plan
View the document Session 15 communication through illustration
View the document Session 16 : Soil preparation, seedbed sowing
View the document Session 17 : Individual interviews
View the document Session 18 : Reproduction by clippings and nursery review
View the document Session 19 : Introduction to extension
View the document Session 20 : Protection and record keeping (Insect collection)
View the document Session 20A : Chicken preparation
View the document Session 21 : The volunteers' role as an extensionist
View the document Session 22 : Tropical horticulture: care, tending and disease control
View the document Session 23 : Women in development - part I
View the document Session 24 : Team building
View the document Session 25 : Building and using a rustic transit
View the document Session 26 : Women in development - part II
View the document Session 27 : Working with groups as an extension worker
View the document Session 28 : Trees: identification & planting
View the document Session 29 : Lesson plan and use of visual aids in teaching
View the document Session 30 : The ugly American
View the document Session 31 : Catchments - sowing of seedlings into catchments
View the document Session 32 : Weekly interview
View the document Session 33 : Agro-forestry
View the document Session 34 : Community analysis introduction
View the document Session 35 : Soils
View the document Session 36 : Community analysis
View the document Session 37 : Irrigation
View the document Session 38 : Review of expectations - mid-way
View the document Session 39 : Problem analysis
View the document Session 40 : Soil erosion
View the document Session 41 : Species report - research demonstration
View the document Session 42 : Cultural values
View the document Session 43 : Wellbeing
View the document Session 44 : Field trip overview
View the document Session 45 : Agro-forestry reports
View the document Session 46 : Weekly interview
View the document Session 47 : Leave on week-long field trip
View the document Session 48 : Pesticides
View the document Session 49 : Review of field trips
View the document Session 50 : Resources
View the document Session 51 : Area measurement, pacing, compass use
View the document Session 52 : Compost heap - greenhouse construction - germination percentage
View the document Session 53 : Culture shock
View the document Session 54 : Range management
View the document Session 55 : Grafting and fruit trees
View the document Session 56 : Professional approaches to interaction with host country officials
View the document Session 57 : Project planning: goal setting
View the document Session 58 : Final interviews
View the document Session 59 : Ecology teams presentations
View the document Session 60 : Graduation

Session 37 : Irrigation

Total time 2 hours


- For the trainees to understand the principles of irrigation,

- For the trainee who has irrigation as a special project to explain the project,

- For the technical trainer to review work done in the nursery.


In this session, the trainees look at their own irrigation systems in the nursery and garden. The trainee for whom this is a special project explains the steps for installation. The technical trainer formally reviews work to date in the nursery.


1. Nursery Irrigation


Flip chart paper, tape, markers, irrigation report, nursery plane.

Exercise 1 Nursery irrigation

Total time 2 hours


The trainees look at their own irrigation systems in the nursery and garden. The trainee for whom this is a special project explains the steps for installation. The technical trainer formally reviews the work done to date in the nursery.



1. The trainee for whom this is a special project gives a presentation. (example follows)


1 hour 15 minutes


2. The technical trainer reviews the progress at the nursery, assesses each trainee's area in the nursery and gives direct feedback on the technical excellence of the trainees' area.


45 minutes


A. The frequency and amount of irrigation depends upon the rate at which water is absorbed by the roots and the water capacity of the soil in the root zone (water capacity should never be below 65%).

B. The rate at which nursery stock absorbs water is determined by the character of stock (species, stage of growth, size, density and whether it is bare rooted or balled stock in containers), weather conditions (temperature, wind and air humidity), and soil (depth, texture, structure and organic matter). For container stock, the characteristics of the potting soil must be considered. More water is needed for containers with porous walls than non-porous walls. Good drainage and wet soil in the base of the containers are important.

C. Older, well established plants should be watered after the hottest part of the day.

D. Seeds and young transplants may need to be watered two or three times per day.

E. Young seedlings and plants are very sensitive to dry soils.

F. Irrigate before planting.

G. The morning after watering, the first two inches of soil should be moist.

1. If dry, irrigate longer.

2. If wet, shorten the irrigation time.

H. Too much water causes leaching, washing away of topsoil and nutrients and can result in root rot (due to a lack of oxygen).

I. If pools of water form in an irrigated area, it is a sign that water is being applied faster than can be absorbed by the soil.

J. Deep watering and soaking make roots go deep and vice versa. Shallow roots damage easier in dry conditions.

K. When irrigating raised beds, use sprinklers or water by hand.


A. Surface

1. Flooding

a. Area must be level,

b. Land to be watered is divided into strips by borders,

c. Border strips are leveled from side to side and made to slope slightly (1 to 2%) from the head ditch to the far end,

d. The lower end may or may not be terminated in a waste ditch (water not used could be used in irrigating another bed),

e. This method is very useful for irrigating sunken seed beds and small beds of transport.

f. Seedlings may be damaged if waterlogged or silt accumulates on their foliage,

g. Surface soil pores can become clogged with sediments and crust can develop on the soil surface.

Figure 23 : Flood irrigation

2. Furrow

a. From the head ditch, water is diverted first into lateral ditches and then into the furrows adjacent to the rows of trees,

b. The head ditch and the furrows must have sufficient slope for the flow of water. The laterals follow the contour of the land,

c. For most nurseries, row spacing is between 50 and 70 centimeters. Length of the furrows should be about 10 meters,

d. There is less evaporation with furrows than with flooding.

e. Furrows are used where naked root stock is grown in rows

Figure 24 : Furrow irrigation


1. Underground pipes or tiles are laid,

2. Water is applied directly to the roots through a means of seepage from the pipes and tiles.

Figure 25 : Subsurface irrigation


1. Terrace,

2. Contour catchment

Figure 26

3. Hill & dale catchment,

4. Roof catchment,

5. Can,

6. Barrel


1. Direct hand irrigation,

2. Uses the correct amount of water.


1. Direct hand irrigation,

2. Uses the correct amount of water.


1. Sprinklers could cause a great water of water.


1. Shade, soil texture and water conservation are important adjuncts to irrigation which can and should be used with most irrigation systems,

2. These conditions should be exploited when no irrigation facilities are available,

3. This system is used to increase the water holding capacity of the soil

a. Soil Structure and Texture

- Soil can be improved by adding compost, manure and decaying organic matter. You do this to build up the sponge structure of the soil.

- The soil can be covered with a mulch.

b. Windbreaks

- Windbreaks are used to stop the sun and wind from depleting soil moisture.

- Trees and nurseries could be surrounded by tall crops, hedges or small walls.

c. Shade

- Shade protects seedlings and soil from the sun.


1. This method requires a minimum amount of water,

2. It is very efficient in water use.

a. A hose is hooked up to a water system. Small holes are cut into the hose at the base of each seedling. This enables you to have direct irrigation to each seedling. A variation of this method is to run smaller hoses from the main hose directly to the seedlings. For these systems, no pump is needed because water is moved by gravity. Small mounds could be built around the seedling as a water catchment devise.


1. Pitchers filled with water are placed underground with only the mouth of the pitcher on the surface. Condensation builds on the pitcher's surface. This condensation is then absorbed by the roots.

Figure 27 : Pitcher irrigation


1. Metal or plastic pipes are laid underground as with the pitcher system. Condensation builds on the pipes and is absorbed by the roots. The water is recirculated by means of a pump. This system could be expensive.