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examBoard: Cambridge
examType: IGCSE
lessonTitle: Agricultural Water Usage
Agriculture is the largest consumer of freshwater globally, accounting for approximately 70% of all freshwater withdrawals. As our global population grows and climate patterns change, understanding how we use water in farming becomes increasingly important for ensuring food security and environmental sustainability.
Key Definitions:
While water covers about 71% of Earth's surface, only 2.5% is freshwater. Of this freshwater, approximately 70% is locked in ice caps and glaciers, 30% is groundwater and less than 1% is readily available surface water in lakes, rivers and streams. Agriculture competes with domestic and industrial uses for this limited resource.
Plants require large amounts of water for photosynthesis, nutrient transport and cooling. A single kilogram of rice requires about 3,500 litres of water to produce, while a kilogram of beef needs approximately 15,000 litres. Different crops and farming methods have vastly different water requirements.
Irrigation is the artificial application of water to crops. Different methods vary in efficiency, cost and suitability for different crops and regions.
Water flows over the soil surface by gravity. Includes flood, furrow and basin irrigation. Efficiency: 40-60%. Low cost but high water use and evaporation losses. Common in developing countries and for rice cultivation.
Water is distributed through a system of pipes and sprayed onto crops. Efficiency: 60-75%. Moderate cost and water use. Suitable for most crops and can be adapted to various terrains. Common in developed countries.
Water is delivered directly to the plant's root zone through a network of valves, pipes and emitters. Efficiency: 90-95%. High initial cost but lowest water use. Ideal for water-scarce regions and high-value crops like vegetables and fruit trees.
The extensive use of water for agriculture has significant environmental consequences that extend beyond the farm.
Excessive water extraction for agriculture can lead to several environmental problems:
Once the fourth-largest lake in the world, the Aral Sea has shrunk to about 10% of its original size since the 1960s. This environmental catastrophe occurred when the Soviet Union diverted water from the rivers that fed the Aral Sea to irrigate cotton fields in Kazakhstan and Uzbekistan. The consequences include:
This case demonstrates how unsustainable agricultural water use can have devastating long-term consequences for both the environment and human communities.
As water becomes increasingly scarce in many regions, adopting sustainable water management practices is essential for the future of agriculture.
Water usage in agriculture varies significantly across different regions due to climate, crop choices, economic development and cultural practices.
In Europe and North America, agriculture typically uses more efficient irrigation systems but often grows water-intensive crops. Water quality issues from agricultural runoff are common concerns. Many farmers have access to technology and capital for water-efficient systems.
In parts of Africa and Asia, smallholder farmers often rely on rainfall or basic irrigation. Water access can be limited and farmers may lack resources for efficient systems. However, traditional water conservation practices are sometimes employed effectively.
In the Middle East and parts of Australia, water scarcity drives innovation in water-efficient farming. These regions often lead in drip irrigation, water recycling and drought-resistant crops, though some still grow water-intensive crops using unsustainable groundwater extraction.
Israel has become a global leader in agricultural water efficiency despite having limited freshwater resources and arid conditions. Key innovations include:
As a result, Israel's agricultural water productivity (crop yield per unit of water) is among the highest in the world, demonstrating how technology and policy can overcome natural water limitations.
Agriculture faces significant water-related challenges in the coming decades, but innovative solutions are emerging.
Agricultural water usage represents the largest human use of freshwater globally. While essential for food production, current practices often lead to water depletion, pollution and ecosystem damage. The future of farming depends on adopting more efficient irrigation methods, implementing sustainable water management policies and developing innovative technologies that can produce more food with less water.
By understanding the challenges and opportunities in agricultural water usage, we can work toward a future where farming practices protect rather than deplete our precious water resources while still meeting the food needs of a growing global population.
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