Each year, farmers in developing countries use some 50– 60 million tonnes of nitrogen as fertilizer. Yet, according to measurements made through the use of isotopes, less than half of that fertilizer actually reaches the crops.
When it comes to producing more crops from every drop of water by increasing water use efficiency, isotopic and nuclear techniques have an advantage over conventional techniques. They can be used as “tags” or “fingerprints” to identify how water and nutrients interact with soil components in crop and livestock production systems. They also can determine whether the water taken up by crops comes from rain, groundwater or irrigation, how it is best used by the plant and how much is actually needed for the crops to grow. This kind of information can guide farmers in making more efficient use of water and optimizing their irrigation scheduling.
Water use efficiency in agriculture. Agriculture is by far the largest global consumer of water, accounting for approximately 70 percent of freshwater withdrawn from lakes, waterways and aquifers around the world – a figure that is even higher in some developing countries and, with population growth, is projected to increase even more. This will put tremendous pressure on the agricultural sector to produce more food with less water.
Both rainfed and irrigated agriculture play important roles in meeting food demand, especially in developing countries, where some 60 percent of crop production is rainfed. Practically speaking, improving water use efficiency in agriculture requires improvements in:
- irrigation practices – in terms of the amount, time and frequency of applications, and
- irrigation technologies – including both drip and sprinkler irrigation.