A recent study published in the journal “Nature” sheds light on the impact of irrigation on the earth system and highlights the challenges that countries face, especially in times of drought.
While the situation in France is worrying, with falling groundwater and temperature records, it is crucial to understand the importance of irrigation and its influence on water resources and agriculture.
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According to experts, about two-thirds of the water tables in France are below normal levels, with some even in alarming states. This situation is part of an international and national context marked by temperature records, knowing that water cycles are closely linked to the earth’s temperature. It is therefore expected that France will face another year of drought, which raises questions, particularly in the agricultural field.
Irrigation accounts for 70% of global water consumption
Irrigation accounts for nearly 70% of water consumption globally, with massive use of fresh water for irrigated areas. Indeed, between 84 and 90% of the water available in the world is used for agricultural purposes for irrigation. This water resource is mainly intended for the fields before reaching our taps.
The review study Nature highlights several consequences of irrigation on the earth system. First of all, it highlights the depletion of groundwater and the increase in soil salinity. The example of Egypt, which was once a fertile crescent 6,000 years ago, demonstrates the harmful effects of the excessive exploitation of groundwater, leading to soil salinization and the drying up of territories. This phenomenon is currently occurring in many parts of the world. In addition, irrigation leads to the leaching of essential nutrients for sustainable agriculture, which affects soil quality and crop nutrition.
Despite the area of agricultural land, irrigation concerns only about 2.5% of the world’s surface. Most of the water used comes from groundwater and surface water. However, it should be pointed out that this water is often lost locally, either through evaporation or direct uptake by plants. In order to facilitate irrigation, dams and water reservoirs are built, which leads to significant changes in the waterways and disturbs the hydrographic balance.
Irrigation has a complex impact on the water cycle. On the one hand, it can contribute to an increase in carbon sequestration, since adequate irrigation promotes plant growth and allows more CO2 to be stored in the soil. However, the study points out that irrigation also causes large flows of methane, a potent greenhouse gas, and mobilizes nitrates from groundwater, further destabilizing the ecological system. Additionally, some areas of intensive irrigation have shown decreased rainfall, while evaporated water often falls downstream, causing flooding further afield.
What solutions?
Faced with these challenges, it is essential to rethink our approach to irrigation. Some solutions such as drip irrigation can make more efficient use of water. In addition, it is important to re-evaluate agricultural supply chains and reduce our consumption of meat, which requires a large amount of agricultural land for raising livestock. By changing our dietary habits, we can use land more sustainably and reduce pressure on water resources.
Irrigation plays a crucial role in global agriculture, but it also presents significant challenges to the earth system. By understanding the consequences of irrigation on water resources, soils and the water cycle, we can develop sustainable solutions to preserve these precious resources. Promoting more efficient farming practices and reducing our meat consumption are key steps towards responsible water use and more sustainable agriculture.