Mediterranean regions, as well as other parts of the world, are currently facing a serious water stress problem.
Very low rainfall, combined with prolonged periods of drought, significantly limits water availability. Furthermore, extreme weather events disrupt agricultural production and cause soil erosion. This, coupled with the increasingly common occurrence of soils with high salinity and low fertility, severely hinders the growth of many crops.
However, there are crops, such as the carob tree, that have proven over decades to be particularly well-suited for combating desertification and stabilizing degraded soils thanks to their drought resistance. Also due to their ability to grow in impoverished soils. Furthermore, this tree’s potential for carbon sequestration makes it a highly suitable tool for promoting climate change mitigation.
However, at present, there is still significant room for improvement in its productivity.
Although it has traditionally been a rain-fed crop, the impact of implementing sub-surface drip irrigation (SDI) has been studied as an effective irrigation method to maximize water efficiency and improve its production without compromising natural resources. SDI represents a paradigm shift and a transformation in the agricultural management of this crop.
UGD allows water to be applied directly to the root zone, which reduces losses due to evaporation and ensures the most efficient use of water resources.
Implementation of UGD in Carob Cultivation
As part of the CICLICA PRIMA research project, work was carried out in 2021 to transform an 8-hectare commercial plot of 7-year-old rain-fed carob trees. The conversion was based on the implementation of a SUB-SURFACE DRIP IRRIGATION system using AZUD PREMIER PC AS 16 emitter tubing at a depth of 30 cm. Additionally, an AZUD LUXON filtration system was installed to ensure the quality of the nutrient solution and prevent clogging of the irrigation emitters.
For the experimental monitoring of this plot, soil probes were installed to measure substrate moisture, temperature, and conductivity; plant sensors were used to measure the trees’ physiological response; and a weather station was set up to provide detailed information on the plot’s environmental conditions.
All these sensors were connected to an AZUD DLOG 600 unit, which enabled comprehensive and continuous monitoring of weather conditions and the entire crop environment for real-time tracking from any device.
Under these conditions, the RGS proved to be an effective strategy for ensuring efficient water use and enabling water supply without losses due to evaporation or runoff.
RGS gave the crop greater resilience to drought. It also helped minimize the negative effects of irrigation water salinity, allowing the carob tree to tolerate water up to 4 dS/m.
Under conditions of severe rainfall scarcity (< 200 mm of annual precipitation), RGS helped improve the carob tree’s vegetative development and increase fruit weight. It also helped maintain more stable production, even increasing yield in some cases.
Under moderate rainfall conditions (400–550 mm of annual precipitation), UGI helped improve production and stabilize the harvest, allowing for a more predictable and consistent yield, which consequently reduced the financial risks associated with the harvest.
Impact of SUB-SURFACE DRIP IRRIGATION
As a result of this transition from rain-fed carob cultivation to irrigated cultivation using SUB-SURFACE DRIP IRRIGATION, the following results were obtained:
- Optimized water use: UGD allows for highly efficient water application without losses due to evaporation.
- Greater water stability: UGD resulted in better-hydrated trees with less water stress.
- Weed reduction: UGD prevented the growth of unwanted weeds.
- Better adaptation to salinity: UGD increased the carob tree’s resilience to irrigation water with high electrical conductivity.
- Positive environmental impact: the RGS enabled irrigation with limited and reduced water consumption, which optimized the crop’s water footprint.
- Increased profitability: RGS ensured more stable and higher-quality production, which resulted in lower financial risk.
The use of soil, plant, and weather sensors, meanwhile, ensured more efficient resource management through continuous and precise monitoring of the system’s climatic and environmental conditions. This information enables real-time decision-making, which directly impacts the optimization of water volumes applied, ensuring that the crop receives the appropriate resources based on its actual needs.
In short, RGS has proven to be an effective and sustainable solution for increasing carob crop productivity in the context of climate change and limited water resources.
Therefore, the adoption of efficient irrigation technologies is key to the future of the agricultural sector.
The CICLICA project is part of the PRIMA program and is funded by the European Union and the Center for Technological and Industrial Development (CDTI).
