Chapter 4
Agroforestry

4.7 Tree Plantations

Suggest if:

• There are good local markets for wood

Not recommended if:

• Land or tree tenure is not secure

• Farmer is unable to invest in future income

"Shade it out!" Tree plantations in Imperata grasslands are a race between the trees and the grass: can the trees suppress the grass before a fire burns them? The trees should be grown as quickly as possible to shorten the time until their canopies close and shade out the Imperata. This may require cultivation, weeding, and fertilization.

4.7.1 Choice of species

Consider first the purpose for the plantation. Many species can be successfully established as plantations in Imperata grasslands (see Appendix E) if given good site preparation, weeding, and fertilizer if necessary. In some cases, assisted natural regeneration might be adequate or even faster (as discussed in Chapter 5).

If the site will be used for agroforestry, one may choose nitrogen-fixing species that will fit well with the agroforestry system to follow. See Sections 4.2 (fallows) and 4.8 (multistory agroforestry and nurse trees).

If the plantation is to generate products for sale, consider the local market for wood, timber, and charcoal.

For some species, different varieties or provenances have very different growth rates, responses to fertilizer, and other characteristics.

Some species are more suited to Imperata grassland rehabilitation than others; they may need less care, and may suppress Imperata and stop being at risk for fire sooner.

4.7.2 Plantation establishment

A plantation with close spacing will have more shade, less grass, and less fuel hazard.

Strategy: dense planting of cuttings and stumps

Strategy: direct seeding

There are a few examples of direct seeding approaches in Imperata. Direct seeding uses a lot of seed and minimum labor per seedling. Only a few very fast-growing species can succeed with so little help.

Strategy: outplanting seedlings

1. Inoculate seedlings in the nursery. Imperata grasslands may be poor in soil microorganisms that help trees obtain nutrients. Add mycorrhizae to nursery soil: obtain mycorrhizae tablets from forestry extension agencies, or gather soil from where the species is already growing vigorously. For nitrogen-fixing species, add rhizobia to nursery soil with prepared rhizobium inoculant packets or obtain soil from a site where the species is growing well. Mix a small amount of this soil with the seed.

2. Grow and harden off seedlings. When planted, trees should already be taller than the vegetation in the prepared field. Only plant healthy, high-quality seedlings with vigorous root systems.

3. Lay out contour lines.

4. Prepare the site. Good site preparation is very important to get the seedlings growing fast so that they can suppress the Imperata before a fire takes place. Large scale reforestation operations have found that complete, mechanized cultivation results in much better growth than strip cultivation; however, this also causes soil erosion. Small landholders using animals to plow are able to leave narrow, unplowed natural vegetative strips along the contour to control soil erosion (Section 4.1.2).

5. Prepare planting holes as for orchards (Section 4.6.2), but holes may be smaller than for high-value trees, and holes may be dug at planting time.

6. Plant and fertilize seedlings following the same procedures as for orchards (Section 4.6.3). For nitrogen-fixing species, P fertilizer may suffice.

7. Maintain seedlings as for orchards (Section 4.6.4). Leguminous cover crops are not recommended because of the closer spacing and lower value of non-orchard trees.