school energy&environment

Water saving in agriculture

Often a great part of water drawn for irrigation purposes doesn’t reach crops due to leaks along the pipes that transport water from the withdrawal point to the fields. Only part of the water reaching fields is used to grow crops, the rest is lost due to evapotranspiration and infiltration in the soil. Different strategies exist to save water in agriculture which, when integrated among them, can increase water saving.
One of the most effective ways to avoid wasting water is irrigating crops according to real necessities of a plant and in the right moment. A precise evaluation of the water volumes and times of irrigation make the use of water more efficient as the volumes necessary to the achievement of the best productions decrease. The estimate of the water balance of crops is the most accurate, low-cost and simple method to evaluate the amount of water necessary to bridge the gap between water consumed by crops due to evapotranspiration and water reaching plants when it rains or from superficial groundwater or capillary resurgence through the soil. This method, even if it’s accurate, is laborious and often difficult to apply, especially at the times of greatest work in an agricultural enterprise. For this reason have been invented softwares that show on a daily basis to farmers when and how much they should irrigate each crop.
Reusing waste water for irrigation is an opportunity offering great benefits, especially in tha face of growing urbanization. Urban waste water, conveniently treated, can be channelled towards agricultural areas for irrigation. Waste water, moreover, supplies crops with nitrogen and part of phosphorus and potassium needed for agricultural production. Reusing waste water limits withdrawal of superficial and subterranean water, reduces the impact of discharging in rivers and favours water saving.
Drip irrigation represents one of the most efficient and sustainable irrigation methods as it allows to direct water only where it’s needed, that means on the base of the plant, close to the roots. It’s a much more efficient system than common sprinkler systems, which spread water on the whole field, even where it’s not necessary with consequent waste of the water resource. In places where this technique has been introduced a decrease in water consumption between 30% and 60% has been registered.
The transition from a method characterised by high losses to a system capable of determining the greatest efficiency of use represents, hence, an indispensable strategy for agricultural water saving. Matching an irrigation system to the characteristics of crops and land is never accidental, infact, no irrigation system adapts perfectly to all situations as each requires special attention to identify the optimal irrigation system. In the reality of a field, hence, not all crops are, for example, practicably irrigable through sprinkling and for many others it’s difficult or uneconomic passing to drip irrigation. Every system can and must be used in the correct manner, adopting all possible precautions to allow achievement of their best efficiency.