Introduction

It is precisely these system/technologies which have to be put to the test to prove their usefulness from an economic consideration. Economic evaluations are important in diagnosis and design of Agroforestry technologies, working out cost: benefit ratios and for rationalization of choice of technologies to be researched or disseminated for development. To understand the role of economic consideration in selecting an Agroforestry system and its modification, some of the existing Agroforestry systems, such as home gardens and wood lots can be examined, which are deeply rooted in the past.

1. Maintains or increases site productivity through nutrient recycling and soil protection, at low capital and labour costs.
2. Increases the value of output on a given area of land through spatial or intertemporal intercropping of tree and other species.
3. Spreads the need for labour inputs more evenly seasonally, thereby reducing the effects of sharp peaks and troughs in activity characteristics of tropical agriculture.
4. Provides productive applications for under utilised land, labour or capital.
5. Creates capital stock available to meet intermittent costs or unforeseen contingencies.

1. Reduces output of staple food crops wherever trees compete for use of arable land and/or depress crop yields through shade, root competition of allelopathic interactions.
2. Incompatibility of trees with agricultural practices such as free grazing, burning, common fields, etc. which make it difficult to protect trees.
3. Trees can impede cultivation of monocrops and introduction of mechanization and so (a) increase labour costs in situations wherein the latter is appropriate and/or (b) inhibit advances in farming systems.
4. Wherever the planting season is very restricted e.g. in arid and semi-arid conditions, demand on available labour for crop production may prevent tree planting.
5. Relatively long production period of trees delays returns beyond what may be tenable for poor farmers and increases the risks to them associated with.

1. To maintain productivity of land in situations of scarce capital, the presence of trees would assists as a substitute for purchased inputs of fertilizer and herbicide and for investments in soil and crop protection.
2. To augment productive use of land in situations of scarce capital and labour, trees, as low-input, low-management crops, would constitute the most effective use of these resources.
3. To increase usable blomass per unit of land area in situations where land and capital are limited and tree/crop/livestock combinations permit fuller use of available labour, then alternative uses of land.
4. To increase income-earning opportunities from use of farm resources as size of landholding and/or site productivity fall below the level at which the household; basic needs can be met from on-farm production.
5. To strengthen risk management through diversification of outputs, wider seasonal spreads of inputs and outputs, and build-up of tree stocks which could be sold to meet periodic or unforeseen needs for capital.

Ag.
Technologies
(Agro Forestry)