Today agriculture uses about 70% of the global freshwater withdrawal, despite the fact that only about 20% of the agricultural land is irrigated. Agriculture is progressively more competing with industrial and private water appropriation, but the water resources are limited and scientists warn that even the current withdrawal is not sustainable anymore. Improvement in efficiency of fresh water use is, therefore, a key component of global food security. This requires considerable investments, innovative technology and know-how in the agricultural sector over the coming decades, which is rightly embraced in the so-called “blue revolution”.
The “agronomic water use efficiency” is the most simple and straightforward measure to quantify water use efficiency in agriculture. It considers the yield a crop has produced per unit of available water. In a way it refers to what has been stated at the UN Millennium Summit in September 2000, “more crop per drop”.
Yara International as a global fertilizer company is engaged in improving agricultural productivity. Yara agronomists demonstrate in trials all over the world that this can be achieved by improving nutrient management. In Europe for example, the proper use of nitrogen fertilizer increased the yield of cereals on average by about 4 t of grain per ha.
In rainfed agriculture, which is globally the dominant production system, it is important to employ crop management strategies that minimize unproductive water use by the crop and avoid water losses from bare soil. Yara research trials show that a good crop nutrition can improve water use efficiency under such conditions. An optimised fertilizer supply to the crop improves crop yield and at the same time makes crop water use more efficient. Calculation of the agronomic water use efficiency from the Yara trials in Europe mentioned above gave an increase in water use efficiency from about 900 kg grain per m3 of water in the treatment without nitrogen fertilizer to 1700 kg grain per m3 of water in the treatment with the optimum nitrogen fertilizer rate.
These data illustrate that nutrient deficiency of crops increases the unproductive water loss. This can be explained by the fact that well-nourished crops have a better soil coverage which is reducing water losses from the bare soil and improves the size and activity of the root system.
Since globally many rainfed systems are nutrient limited, nutrient management can therefore substantially increase crop yield for a given amount of available freshwater and in turn improve water-use efficiency. This fundamental relationship between crop nutrition and water consumption by crops explains why Yara International as a global fertilizer company is engaged in research to explore new ways and innovative technologies to further improve nutrient and water use efficiency. Research projects have been launched with the aim to develop innovative solutions for crop nutrition and water management under conditions of water scarcity in order to improve efficiency of both water and nutrient use of crops to realize “more crop per drop” in a sustainable way.
Joachim Lammel is Director of R&D at Yara International.