Deficit irrigation to optimize water without losing quality

The management of water in agriculture is called deficit irrigation (RD), which implies that an amount of water less than the water needs of the crop is supplied, obtaining its maximum potential. , and enough to avoid a significant reduction in its performance.

This strategy seeks to optimize the use of water in areas where the resource is scarce, while maintaining sustainable and economic agricultural production.

Modalities of deficit irrigation

1-Sustained deficit irrigation

This irrigation modality is applied in cases of high-frequency irrigation in which the crop is expected to use part of the water stored in the soil during the rainy season. We continuously apply an amount of water less than the total need of the crop throughout its growing season.

  • Consistency in deficit irrigation: A constant and reduced amount of water is applied throughout the crop's growth cycle.
  • Simple Management: It is simpler to apply and manage compared to controlled deficit irrigation, since it does not require frequent adjustments based on the stages of crop development.
  • Adaptability: It should be applied to crops that are relatively tolerant to water stress. Examples: Cereals, some fruit trees and vineyards that can increase their sugar concentration.

2-Low frequency deficit

After the rainy period the soil is close to field capacity; When the dry season arrives, we wait for the soil moisture content to decrease until it reaches the permissible deficit, that is, until AD is exhausted.

At that point, abundant irrigation is applied, until the soil reaches field capacity. Care must be taken not to apply excessive watering, since the excess water would be lost through percolation. The frequency of irrigation would be determined by the consumption of the crop, volume of the rhizosphere and type of soil.
This type of irrigation is applied only in cases in which the irrigation system of the farm makes it burdensome to increase the irrigation frequency.

In fruit trees, the concentration of sugars can increase in periods close to the permissible deficit.

Monitoring with humidity sensors is recommended to avoid causing water stress in the plants and avoiding excessive watering.

Puede ser aplicable en:

  • Citrus: Low frequency deficit irrigation (RDBF) can be beneficial to improve fruit quality without significantly affecting yield.
  • Vineyards: RDBF can increase the concentration of beneficial compounds in grapes, improving the quality of the wine.
  • Olive trees: They can benefit from RDBF, since they are relatively tolerant to water stress and this technique can improve the quality of olive oil.

3-Controlled deficit irrigation

This modality is known abbreviated as RDI {Regulated Deficit Irrigation) in the Anglo-Saxon literature (Chalmers et al., 1981). It is a water management technique in agriculture that consists of applying amounts of water smaller than the total needs of the crop. Reduce irrigation, and even eliminate it, at times when the crop is less sensitive to water stress, irrigating with 100% ETC only in the crop periods in which water stress can cause significant losses in its yield.

It is important to identify the development stages most sensitive to water stress, using humidity and temperature sensors.

Develop an irrigation plan that considers the specific needs of the crop at each stage of growth.

It is advisable for:

  • Vineyards: In viticulture, RDC is used to improve the quality of the grapes and, therefore, the wine, by concentrating irrigation during the flowering phase and reducing it by other stages.
  • Citrus: In citrus cultivation, RDC can be applied to maintain the quality of the fruit and ensure adequate yield, watering more during fruiting and less in other phases.
  • Cereals: In crops such as wheat, RDC can be useful to optimize water use during the grain filling phase.
  • Olive Tree: The moments in which water cannot be lacking are flowering, fruit setting and the first phases of fruit growth, and in the last stage of the fruit growth phase. During most of the fruit growth period, the olive tree is less sensitive to lack of water. With an RDC strategy you can save up to 50% of the amount of irrigation water needed to replenish real evapotranspiration, ETC, without notable harvest reductions. Its difficulty lies in knowing which are the moments of greatest sensitivity to water stress.

4-Partial Drying of the Roots

The acronym for this irrigation method comes from its English name, Partial Rootzone Drying (PRD) (Dry and Loveys, 1998). In this case, it is irrigated with less water than required to replenish ETC and, also, alternately in half of the rhizosphere, changing to the other half every time. 2 or 3 weeks.

Basically, it is considered that if irrigation water is applied to one half of the root system, signals are generated in the roots of the other half in response to the decreasing level of water in the soil, signals that travel to the aerial part of the plant. plant and induce greater stomatal closure, therefore reducing transpiration and increasing water use efficiency.

The signals stop being generated when the soil dries out too much, hence it is necessary to water again after a certain time, which is considered to be about two weeks, or three in the case of trees and plants whose root system explores a large volume of soil.
The total irrigation volumes applied with PRD are usually similar to those used with RD, ranging between 50 and 70% of ETC, for the most cases.
It must be taken into account that the irrigation system required for the application of PRD requires a double system of emitter carrying pipes.

Applicable to:

  • Vineyards: In viticulture, DPR has been used to improve grape quality and water use efficiency, resulting in better quality wines.
  • Fruit trees: In fruit trees such as apple and pear trees, DPR can increase fruit quality and control vegetative growth.
  • Horticultural Crops: In crops such as tomatoes and peppers, DPR can increase the concentration of solutes, improving the flavor and quality of the fruit.

Advantages of Deficit Irrigation

  1. Water Savings: Less water is used, which is crucial in areas with limited water resources.
  2. Reduced Costs: By reducing water consumption, the costs associated with irrigation are also reduced.
  3. Improved Product Quality: In some cases, it can improve the quality of agricultural products, such as increasing the concentration of sugars in fruits.
  4. Adaptation to Climate Change: Facilitates the adaptation of agricultural systems to drought conditions and climate change.
  5. Reduction of Runoff and Nutrient Losses: Less irrigation can result in less runoff and leaching of nutrients, reducing pollution of water bodies.

Disadvantages of Deficit Irrigation

  1. Risk of Loss of Production: If not managed properly, it can lead to a significant reduction in yield.
  2. Need for Precise Monitoring: Requires constant and precise monitoring of the water needs of the plants.
  3. Dependency on Climatic Conditions: Variable climatic conditions can affect the effectiveness of deficit irrigation.

In summary, deficit irrigation is an effective strategy for sustainable water management in agriculture, but its success depends on careful implementation and continuous monitoring to balance crop water needs with resource availability.

Our agronomic department is always available to advise on all controlled irrigation methods.

Vineyards with deficit irrigation controlled by sensors
Vineyards with deficit irrigation controlled by sensors

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