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Module 2

2. Nurseries and Propagation

This module provides details on : major components of nursery establishment, It also contains guidelines on seed collection, different methods of raising seedlings, and other ways to propagate plants. Fruit-tree grafting techniques are explained, as well as the function of nitrogen-fixing organisms and mycorrhizae. Same principles of nursery management are outlined.

Establishing a Nursery

Before going ahead with nursery plans, a thorough economic analysis is suggested since a good nursery can be an expensive undertaking. In many situations, commercial seedlings are the best and cheapest source of quality planting material.

Selecting the Site

The nursery site is important to ensure efficient production of good-quality plants and easy nursery management. The following factors should be considered:

Determining Nursery Size

Calculation of nursery size is based principally on the expected demand for seedlings and the main plant growing area required. It is also important to remember overlapping production cycles, for example, seedlings being grown to replace those that die after the first planting. These replacement seedlings (at least 10-20 % and as high as 45 %, depending on initial germination and survival) will take up space in the first cycle as well as the second cycle. This means that, over a period of two cycles, nearly half of the seedlings will take up twice as much space as the seedlings that are outplanted first.

Example
Let's calculate the size of a nursery required for the following average annual production:

1) 12,000 polypots (3 x 7 in.)

Space is required for 12,000 x 1.25 = 15,000 polypots (to allow for 25% loss and culling). Approximately 200 polypots cover an area of 1 m² when spaced out:

15,000÷200 = 75 m²

Half of these plants require twice as much space, because they are in the nursery for more than 12 months and need to be spaced further apart to avoid crowding.

37.5 m² + (37.5 m² x 2)=112.5 m²

2) 18,000 polypots (4 x 7 in.)

Space is required for 18,000 x 1.25 = 22,500 polypots (to allow for 25% loss and culling). Approximately 115 polypots cover an area of 1 m2 when spaced out:

22,500 ÷ 115 = 196 m²

Half of these plants require twice as much space, because they will be in the nursery for more than 12 months:

98 m² + (98 m² x 2) = 294 m²

3) 500 bamboo cuttings
Space is required for 500 x 1.40 = 700 polypots (to allow for 40% failure in rooting).
Four cuttings can be planted per square meter:

700÷4 = 175 m²

Twice as much space is required because the cuttings spend more than 12 months in the nursery:

2 x 175 = 350 m²

4) 2,000 stumps

Space is required for 2,000 x 1.25 = 2,500 stumps (to allow for 25% loss and culling). Approximately 100 stumps cover an area of 1 m²:

2,500 ÷100 = 25 m²

Twice as much space is required, because the stumps spend more than 12 months in the nursery:

25 m² x 2 = 50 m²

5) The total area required for the above 4 nursery beds = 806.5 m²

To allow for paths between beds and for terrace risers, this area must be multiplied by a factor of 1.5 for a nursery that is not terraced (slope of up to 2%), and by a factor of 3 for a terraced nursery (slope of 3 - 20%).

A nursery that is not terraced would, therefore, need 1,210 m² for the main plant growing area. A terraced nursery would, therefore, need 2,420 m².

In addition, space will be needed for seed beds, a potting shed, a compost-making area, an office, and parking area. The total area required is likely to be 1,600 1,700 m², on a level site, and almost twice as much (3,200 3,400 m²) on a steep site.

Basic Site Requirements

Note: Where waterlogging is frequent, raised seedbeds should be used.

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In addition, a nursery can also have a:

Nursery Design

Before beginning construction, a sketch plan should be drawn which includes:

The shape of the nursery should be square or rectangular. An irregular shape means that boundary lines are longer and this increases the amount of fencing. The ideal shape is square since this reduces the distance between seedbeds /potbeds and the area where seedlings are planted.

When the plan is complete, every element should be checked carefully at the nursery site. Farmers should ensure that the location of each component is the best one possible by keeping in mind what it is supposed to do and how this function is connected to other components.

Nursery Construction

Land should be cleared of all vegetation and rocks. Where earthworks such as terraces are necessary, drains should be built early to prevent rain damage. Drains should be built along the top edge and down the sides of the nursery, as well as alongside the paths to prevent the paths themselves from becoming drains.

Strong fences, large enough to keep all animals away, are a good investment. The gate should be simple and easy to open.

When the area for the seedbeds and potbeds has been leveled, the corners and edges can be marked with wooden sticks and strings. Flat stones, wood planks or other barriers can then be set on edge in trenches along these boundary lines to support the beds. The top of the barrier should be 10-12 cm above soil level. The ground around the stones or other material should be compacted so that they don't erode into the beds.

Tools Required

Nursery operators should refer to the following suggested checklist of tools and equipment. In different countries these tools will vary slightly.

Seed Handling

Seed Collection

Seed can be collected locally or obtained from distributors, seed centers, forest services, and research institutes. Successful planting is more likely if the seed is:

If collection is local, it is important to know where the best trees are located. Seed should come from an area that is as similar as possible (altitude, amount of rainfall, type of soil, etc.) to the area where the seedlings will be grown. Seed should be collected from donor trees with --the desired characteristics (see Module 1).

For construction wood and timber, for instance, straight trees are desirable. For fuelwood production, fast growth and ready coppicing are more important than a straight, unbranched trunk. For fodder, abundant leaf production and good recovery after pruning or browsing are essential features. For fruit, local taste and market patterns are most important.

Remember:

It is important to know when to collect seed:

Whenever possible:

When transporting fruits:

Calculation of the amount of seed required:

SW = 1.25N/PW

where:

Sw = Seed required in kg or other unit of measure.
N = number of seedlings required for planting
1.25 = factor that adds a 25 % reserve

 

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