Yusuf, you are dead right, water productivity has to be more aggressive addresses than productivity in water deficit areas where this issues more importance. Unfortunately very thin line exists between water productivity and water use efficiency...

Of course there is urgent need to shift from yield productivity to water productivity even if there is certain reduction in production. This can be compensated by increase in cultivated area irrigated by saved water. Like in India, a major portion is rainfed area, so if water productivity id given more importance than same water can be used to get more production and the pressure (nutrient extraction) on Indo-gangetic plains can be controlled.

There may be many things to consider, since basically all life depends on water and needs consideration if developing an integrated plan on water resources and its various uses. Politics, laws, court decisions, landowner, rainfall, vegetation, crops, community or urban needs, power generation, and instream, groundwater and storage supplies pertinent to the situation may all factor into these considerations. Certainly, if you are a landowner or community with known supplies and needs of water, the decisions on how best to use available supplies to improve productivity are appropriate, or find ways to store or purchase more, or make operations more water efficient, would be considerations. Since you mention countries, each one may have differing needs and objectives, as well as perspectIves on what are appropriate uses for water, and priority when supplies run low, such as drought. And even within agriculture, there may be tradeoffs, such as convincing the rancher to forego the irrigation for third and/or fourth hay cutting, to allow enough water for the neighboring or downstream farmer. Bringing water issues out for discussion, balance and economic consideration plans for water storage and allocation can help ease these issues and uncertainties that individuals as well as communities and countries face.

Water use efficiency (WUE) and water productivity (WP) are two different terms. However, they seem to cause some confusion only among agronomists.The Water Productivity term plays a crucial role in modern agriculture which aims toincrease yield production per unit of water used, both under rainfed and irrigated conditions.  The recent literature shows that what previously was wrongly defined as Water Use Efficiency has been renamed in “Water Productivity” in the early 1980’s. The key principles for improving water productivity at field, farm and basin level, which apply regardless of whether the crop is grown under rainfed or irrigated conditions, are: (i) increase the marketable yield of the crop for each unit of water transpired by it; (ii) reduce all outflows (e.g. drainage, seepage and percolation), including evaporative outflows other than the crop stomatal transpiration; and (iii) increase the effective use of rainfall, stored water, and water of marginal quality...Some PDFs enclosed for better understanding on the issue...

Useful points Dr. Anoop could you please provide details on possible indicators of water productivity to account for value not accounted for in crop production.

Very interesting! So what are best indices for assessing water productivity?

 i think there are two issues in this regard. one is about water efficiency when we use water to produce such crops where we need flood irrigation even in the water deficient area like Punjab. over the period of time we are producing rice across punjab. second, we need to understand the existing cropping pattern which emerged out due to green revolution. we should adress this question in the lines of reorganizing cropping pattern.

regards  

 I find hardly any such instance of changing the land use pattern , which is such a glorified cropping sequence in yesteryears. If we have that strong daatbase support to look at such issues, probably , this will be the biggest contribution of land-use-planning . 

Lets come to the point Dr Malhotra , you have raised  about  the criteria for water productivity . Infact , no criteria will be acknowledged , if water productivity is nt linked with crop yield on a sustained basis backed by better water use efficiency, since the productivity  itself , is a ratio between a unit of output and a unit of input ..

For example, the so-called ‘crop per drop’ approach focuses on the amount of product per unit of water. Another approach considers differences in the nutritional values of different crops, or that the same quantity of one crop feeds more people than the same quantity of another crop. When speaking of food security, it is important to account for such criteria (Renault and Wallender, 2000). Another concern is how to express the social benefit of agricultural water productivity. All the options that have been suggested can be summarized by the phrases ‘nutrient per drop’, ‘capita per drop’, ‘jobs per drop’, and ‘sustainable livelihoods per drop’. There is no unique definition of productivity and the value considered for the numerator might depend on the focus as well as the availability of data. However, water productivity defined as kilogram per drop is a useful concept when comparing the productivity of water in different parts of the same system or river basin and also when comparing the productivity of water in agriculture with other possible uses of water.

Crop water production is governed only by transpiration. As it is difficult to separate transpiration from evaporation from the soil surface between the plants (which does not contribute directly to crop production), defining crop water productivity using evapotranspiration rather than transpiration makes practical sense at field and system level. In irrigated agriculture in saline areas, the leaching requirement, i.e. the amount of water that needs to percolate to maintain rootzone salinity at a satisfactory level, should also be included together with evapotranspiration in the amount of water that is necessarily depleted during plant growth. Other non-productive but beneficial uses could be included. Examples are evapotranspiration by windbreaks, cover crops, and the water used in wetting seedbeds to enhance germination.

The question of considering water losses from seepage and field percolation as consumption does not receive a unique response. If this water is of no use downstream or if it generates further pollution such as that resulting from geological salt leaching (e.g. San Joaquin Valley, California, the United States of America), then it must be accounted for as consumption. Solutions to minimize these losses, such as canal lining or water improvement application, then have a positive effect on productivity. However, from a broader environmental point of view, it can be important to consider the impact of the outflow of an irrigation system on the overall productivity of an ecosystem.Based onUnlocking the water potential of agriculture...by Español  Français