Glossary | 567

Subsidy Transfer of resources to an entity, which either re­duces the operating costs or increases the revenues of such entity for the purpose of achieving some objective.
Subsistence Agriculture Agriculture carried out for the use of the individual person or their family with few or no outputs available for sale.
Sustainable Development Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
Sustainable Land Management (SLM) A system of technol­ogies and/or planning that aims to integrate ecological with socioeconomic and political principles in the man­agement of land for agricultural and other purposes to achieve intra- and intergenerational equity.
Sustainable Use of Natural Resources Natural resource use is sustainable if specific types of use in a particular ecosystem are considered reasonable in the light of both the internal and the external perspective on natural re­sources. "Reasonable" in this context means that all ac­tors agree that resource use fulfils productive, physical, and cultural functions in ways that will meet the long-term needs of the affected population.
Technology Transfer The broad set of deliberate and spon­taneous processes that give rise to the exchange and dissemination of information and technologies among different stakeholders. As a generic concept, the term is used to encompass both diffusion of technologies and technological cooperation across and within countries.
Terms of Trade The international terms of trade measures a relationship between the prices of exports and the prices of imports, this being known strictly as the barter terms of trade. In this sense, deterioration in the terms of trade could have resulted if unit prices of exports had risen less than unit prices for imports. The inter-sectoral terms of trade refers to the terms of trade between sectors of the economy, e.g., rural and urban, agriculture and industry.
Total Factor Productivity A measure of the increase in total output which is not accounted for by increases in total inputs. The total factor productivity index is computed as the ratio of an index of aggregate output to an index of aggregate inputs.
Tradeoff Management choices that intentionally or otherwise change the type, magnitude, and relative mix of services provided by ecosystems.
Transgene An isolated gene sequence used to transform an organism. Often, but not always, the transgene has been derived from a different species than that of the recipi­ent.
Transgenic An organism that has incorporated a functional foreign gene through recombinant DNA technology. The novel gene exists in all of its cells and is passed through to progeny.
Undernourishment Food intake that is continuously inad­equate to meet dietary energy requirement.
Undernutrition The result of food intake that is insufficient to meet dietary energy requirements continuously, poor absorption, and/or poor biological use of nutrients con­sumed.


Urban and Peri-Urban Agriculture Agriculture occurring within and surrounding the boundaries of cities through­out the world and includes crop and livestock production, fisheries and forestry, as well as the ecological services they provide. Often multiple farming and gardening sys­tems exist in and near a single city.
Value Chain A set of value-adding activities through which a product passes from the initial production or design stage to final delivery to the consumer.
Virtual Water The volume of water used to produce a com­modity. The adjective 'virtual' refers to the fact that most of the water used to produce a product is not contained in the product. In accounting virtual water flows we keep track of which parts of these flows refer to green, blue and grey water, respectively. The real-water content of products is generally negli­gible if compared to the virtual-water content.
Waste Water 'Grey' water that has been used in homes, ag­riculture, industries and businesses that is not for reuse unless it is treated.
Watershed The area which supplies water by surface and sub­surface flow from precipitation to a given point in the drainage system.
Watershed Management Use, regulation and treatment of water and land resources of a watershed to accomplish stated objectives.
Water Productivity An efficiency term quantified as a ration of product output (goods and services) over water input. Expressions of water productivity.  Three major expres­sions   of   water   productivity   can   be   identified:   (1) the amount of carbon gain per unit of water trans­pired  by  the  leaf  or  by  the  canopy  (photosynthetic water  productivity);   (2)  the  amount  of water trans­pired   by  the  crop   (biomass  water  productivity);   or (3) the yield obtained per unit amount of water trans­pired by the crop (yield water productivity). Agricultural water productivity relates net benefits gained through the use of water in crop, forestry, fishery, live­stock and mixed agricultural systems. In its broadest sense, it reflects the objectives of producing more food, income, livelihood and ecological benefits at less social and environmental cost per unit of water in agriculture. Physical water productivity relates agricultural production to water use—more crop per drop. Water use is expressed either in terms of delivery to a use, or depletion by a use through evapotranspiration, pollution, or directing water to a sink where it cannot be reused. Improving physical water productivity is important to reduce future water needs in agriculture. Economic water productivity relates the value of agricul­tural production to agricultural water use. A holistic assessment should account for the benefits and costs of water, including less tangible livelihood benefits, but this is rarely done. Improving economic water productivity is important for economic growth and poverty reduction.