Recognizing that meeting societal demand for food is a global challenge, as recent estimates indicate that the world will need 60% more cereal production between 2000 and 2050 (FAO, 2009), the fertilizer industry would like to draw attention to the synergy between water and nutrient management and the solutions it can provide for increased sustainable food production.
The objective of nutrient use is to increase the overall performance of cropping systems by providing economically optimum nourishment to the crop while minimizing nutrient losses from the field into the environment, including into water. Therefore, NUE and WUE are inextricably linked concepts.
Trials have shown that water use efficiency can be improved through nutrient management (Hatfield et al., 2001). Nutrient availability affects aboveground biomass, canopy cover to reduce soil evaporation, plant residue production, nutrient dynamics in soil, and thereby improves crop growth and WUE (Norton and Wachsmann, 2006).
Moreover, data from a lysimeter experiment conducted in Canada on spring wheat offers an excellent example of the relationship between NUE measures and WUE across a range of N levels. The study included both rainfed (dry) and irrigated) treatments and shows the tremendous impact water status can have on yield response to N.
Even though NUE generally decreased as N rates increased, the simultaneous increase in WUE and yield until an optimum N rate was attained improved over-all system performance, showing that efficient and effective use of either water or crop nutrients requires that both be managed jointly at optimum levels within a specific crop system.
Numerous efficiency and productivity enhancing nutrient and water management technologies and practices exist, but many are underutilized. The International Fertilizer Industry Association stresses that locally defined guidelines for NUE that are specific for nutrients, soils, cropping systems and mindful of plant-water status are needed to help farmers identify where improvements are most needed and easiest to advance.
Maria Antip