Farmers own or rent land. So they instinctively think of productivity in terms of agricultural output per unit area of land. So we are used to the idea of productivity being defined as tons or quintals of crop per acre or hectare. But with a growing population and changing climate, water scarcity is a reality across the world and is set to only get worse. This calls for thinking of agricultural productivity also in terms of Water Productivity. In agriculture, water productivity is the amount of value in terms of benefits and services created per unit volume of water consumed. This value depends on the amount of output as well as the nutritional and socio-economic value of the output derived per unit of water that is consumed. So the idea of Water Productivity goes beyond the catchphrase “more crop per drop” to include “more value per drop”.
This distinction provides important insights and can therefore support agriculture and water management decisions on the ground as well as inform policies. Economic water productivity, which measures the economic or financial value created with the volume of water consumed, or the number of jobs created per volume of water (‘job per drop’) is of much concern in countries with high unemployment where there is an urge to create jobs. For example, using non-renewable groundwater for high value semi-mechanized export production of potatoes may create high returns in yield per hectare or the financial revenues. However, the benefits may accrue to a few large producers only, with very few jobs created, no contribution to national food security and hidden subsidies in production (for instance in pumping).
The water in productivity
All the fractions above have one common denominator being water. The history rewritten in short is that crop physiologist started looking at how a plant would grow and the amount it would transpire (T) or sweat, which would later on be coined as consumed beneficial water use. Irrigation specialists would simply said, consider the amount of water delivered to crops and to what extent that amount is consumed, both beneficially (T) and non-beneficially by means of evaporation (E) and what is not consumed. Non-consumed water could be water that infiltrates, drains through soils or over surfaces. An important point that irrigation specialists or water managers add however here is that non‐consumed water, may by virtue of it infiltrating or running of into surface water, become usable again called a recoverable fraction. This opportunity of re‐use then implies that water applied and not consumed the first time may be consumed the second or third time. However, water that is applied to crops often dissolves salts and fertilisers, which affects the quality of the water and may eventually imply that water is not suitable for other purposes, reusing would then come at a cost or the water would simply be considered lost. As non-consumed water is difficult to measure and considering the complexities and implications of recovering and reusing water, the water consumption therefore in the water productivity fraction sticks to what soil and crop scientists commonly define it. Being a combination at field level of evaporation (E) and transpiration (T) also called evapotranspiration (ET).
Water productivity interventions
This website provides a whole range of interventions impact on water productivity and yield. This overview does not comprise an exhaustive overview of all the possibilities, nor does it solely refrain to those that might only impact water productivity. Also it is important to consider that the expectations associated with water productivity are not only restricted crop performance (the bio-physical) but may also include economic, social, ecological and technical (as referred to above. Water productivity measures also do not only take place at plant level, but also at field, irrigation scheme and policy level.
What is important to consider that the indicators suggest an impact, which implies a (significant or measurable) change over time for a specific place and for some indicators also for same crops. The following considerations are provided when browsing through the interventions list and write-up:
most if not all solutions are not stand-alone solutions if intending to improve water productivity;
besides introducing solutions, improving water productivity comes with: adequately being able to measure to do so (as this compendium suggests); performing the right comparison; having a clearly identified objective; and keeping the intended impact in mind;
keep in mind the potential trade-offs a solution may have in a given context, with regards to water resources management (within a basin or hydrogeological unit); the environment; the societal and economic impact. These trade-offs are mentioned in the descriptions of the solutions.
Resources and portals
FAO. WaPOR portal. https://wapor.apps.fao.org/home/WAPOR_2/1
FAO. Why agricultural water productivity is important for the global water challenge. www.fao.org/3/y4525e/y4525e06.htm
IWMI. World Water Productivity: Current Situation and Future Options (https://publications.iwmi.org/pdf/H032641.pdf)
Perry, C. (2011). Accounting for water use: Terminology and implications for saving water and increasing production. Agricultural Water Management, 98(12), 1840–1846. https://doi.org/10.1016/j.agwat.2010.10.002.
TheWaterChannel (http://thewaterchannel.tv/dossiers/water-productivity) and Youtube channels of FAO, IWMI
Zwart, S. 2010. Benchmarking water productivity in agriculture and the scope for improvement. PhD thesis. https://ris.utwente.nl/ws/portalfiles/portal/18476489/PhD_thesis_SanderZwart.pdf