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close this bookSpecial Public Works Programmes - SPWP - Planting Trees - An Illustrated Technical Guide and Training Manual (ILO - UNDP, 1993, 190 p.)
View the document(introduction...)
View the documentPreface
View the documentIntroduction
close this folder1. Planning a plantation
View the document(introduction...)
View the document1.1 What regeneration method to use?
View the document1.2 What species to establish?
View the document1.3 Whether to plant a single tree species or a mixture of several?
View the document1.4 What type of planting stock to use?
View the document1.5 What planting pattern to use and how many seedlings to plant?
View the document1.6 When to plant?
View the document1.7 How to protect the seedlings?
View the document1.8 The plantation plan
close this folder2. Preparing the planting site
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View the document2.1 Clearing vegetation
View the document2.2 Ground preparation
View the document2.3 Marking where to dig the holes
View the document2.4 Digging holes
View the document2.5 Soil and water conservation measures
close this folder3. Handling seedlings
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View the document3.1 Packing and transport of seedlings
View the document3.2 Storing seedlings
View the document3.3 Quality of seedlings and grading
View the document3.4 Stripping and trimming
View the document3.5 Transporting seedlings from the road to the planting site
close this folder4. Planting techniques
View the document(introduction...)
View the document4.1 Digging the holes
View the document4.2 On-site distribution of the seedlings
View the document4.3 Planting
View the document4.4 Use of fertilizers
close this folder5. Adapting planting techniques to different site conditions
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View the document5.1 Favourable sites
View the document5.2 Sites with high grass
View the document5.3 Waterlogged sites
View the document5.4 Dry sites
View the document5.5 Eroding slopes and rocky sites
View the document5.6 Steep slopes
View the document5.7 Sand dunes
View the document5.8 High altitudes with snow
close this folder6. Maintaining plantations
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View the document6.1 Weed control
View the document6.2 Protection from grazing
View the document6.3 Fire prevention
View the document6.4 Protection from insects, diseases and rodents
View the document6.5 Fertilizers
View the document6.6 Replacement planting
close this folder7. Planting trees outside woodlots and forests
View the document(introduction...)
View the document7.1 Trees in crop and grazing land
View the document7.2 Alley cropping
View the document7.3 Intercropping in rotation
View the document7.4 Intercropping for tree planting
View the document7.5 Shelterbelts
View the document7.6 Road-sides and river-sides
View the document7.7 Homesteads and public places
close this folder8. Organizing the work
View the document(introduction...)
View the document8.1 Planning
View the document8.2 Workforce
View the document8.3 Labour requirements over the year
View the document8.4 Worknorms
View the document8.5 Coordinating the work
View the document8.6 Tools and equipment
View the document8.7 Supervision and control
View the document8.8 Records to keep
close this folder9. Working conditions
View the document(introduction...)
View the document9.1 Hours of work and rest
View the document9.2 Nutrition and amenities
View the document9.3 Wage systems
View the document9.4 Training, job content and labour-management relations
View the document9.5 Safety
close this folderAppendices - Technical sheets
View the documentAppendix 1 - Surveying and mapping of large planting sites
View the documentAppendix 2 - Laying out and preparing soil and water conservation structures
View the documentAppendix 3 - Survival count
View the documentSome useful guides/handbooks
View the documentTitles in the series of training elements and technical guides for SPWP workers

6.1 Weed control

Grasses, herbs and other vegetation on the planting site compete with the seedlings for light, water and nutrients. Cutting or removing the vegetation from around the seedlings reduces the competition. If weeding is neglected, the seedlings will die. How often and in which way the weeding is carried out depends on the climate, the soil, the species planted and the size and quality of the seedlings used.

The more hot and humid the climate, the more weeding operations are needed. Depending on weed competition in some places it will be enough to weed once during the first year. In other places three or more weedings per year might be needed. If small and poor quality seedlings are used, the number of weeding operations needed will increase. As a general rule of thumb there should be:

2-3 weedings during the first year after planting;
1-2 weedings during the second year after planting;
0-1 weeding during the third year after planting.

Weeding must be carried out early, before the seedlings suffer from being smothered by weeds. Since the growth of grasses is fastest during the rainy season, the first weeding should begin immediately after the planting is finished at the end of the rainy season. If the weeding is carried out too late, the seedling will not be able to survive the sudden exposure to light after the weeding and it will die.

Cutting grass and other vegetation is a less effective form of weeding, since the grass roots remain in the soil and keep competing with the roots of the trees. On sites where competing vegetation is less vigorous and where more weed-tolerant tree species have been planted, however, cutting weeds in a 1m-wide circle around each tree seedling is sufficient.

Weed control


2-3 weedings during the 1st year


1-2 weedings during the 2nd year


0-1 weeding during the 3rd year


If weeding is too late, the seedling will die because of the sudden exposure

Grass-cutting on the entire site is also a way of harvesting the grass. It is recommended in areas where the grasses grow high and are hard-stemmed, and also when seedlings are small, because the light competition and physical damage of the tall grass can suppress seedling growth. It also helps to reduce the risk of bush fires. If grass is cut for fodder the nutritive value will be highest when the grass is young and green immediately after the rains, before flowering. If the grass is not carried away from the plantation and used it should be mulched around the seedling. If thick enough the mulching layer will suppress the further growth of weeds, reduce water loss and provide the seedling with nutrients. Mulching may, however, attract termites and rodents and should be avoided in areas where such damage is common.

Cutting the vegetation alone is not adequate on sites with heavy grass competition, when the seedlings are small and for some weed-sensitive species (teak, some eucalyptus species). Hoeing should also be done, preferably in dry weather. At least one square metre around the plant should be hoed.

A very effective way to ensure that the weeding is carried out well and that the seedlings are protected is to intercrop trees and agricultural crops for the first 1-2 years after planting. For a description see section 7.4. Tools required for grass-cutting are the same as for clearing. They are described in section 2. 1.

A sickle is an additional tool, useful for cutting soft stem grasses. It should be used if the seedlings are small and difficult to locate, because the cut is easy to control. The scythe is otherwise preferable since it permits work in an upright position. A sickle weighs about 0.3 kg and the length of the sickle blade is about 0.3 m. It is used with one hand and the cutting swing is made away from the seedling.

It might be necessary to remove climbing vines in moist and humid regions. The best method is to use a Y-shaped stick to push the vine up. The vines thus removed from the tree should not be cut, as they would sprout again, but curled up and deposited at the base of the tree.

Grass-cutting


Grass-cutting decreases competition and provides fodder


Figure

Mulching:

- suppresses weedgrowth
- reduces waterloss
- provides nutrition


Often both grass-cutting and hoeing is needed


Sickle


Removal of climbers