Nº 1 2014 > WSIS Stocktaking
Smart irrigation for sustainable agriculture in Abu Dhabi
Case study — United Arab Emirates
Water conservation is crucial in the United Arab Emirates in the face of increasing demands from a growing population. Because the agriculture sector accounts for up to 75 per cent of the country’s annual water consumption, improving water management in that area offers great potential for reducing the overall amount of water consumed. Introducing smart irrigation technology that improves the efficiency of water use will not only help farmers to make their activities more profitable, but also increase the sustainability of agriculture in general.
The information in this article was provided by the Abu Dhabi Food Control Authority of the United Arab Emirates.
Smart irrigation technology
Greenhouse vegetables require water to grow and ripen, so irrigation is essential. But an automatic irrigation system that is triggered by a timer may provide water that is not needed. Soil moisture sensors can reduce the number of unnecessary irrigation events. Automation of irrigation systems based on soil moisture sensors has the potential to maximize the efficiency of water use by maintaining soil moisture at optimum levels.
Farmers in the United Arab Emirates have to cope with sporadic low rainfall coupled with harsh climatic conditions. An added difficulty is that the country’s sandy soil has low water-holding capacity. If the amount of water present is insufficient for plant needs, then stress occurs. The quality of plants may be reduced or — in cases of severe water shortage — the plants may die. Irrigation is therefore common.
Most soil moisture sensors are designed to estimate soil volumetric water content based on the dielectric constant (soil bulk permittivity) of the soil. The dielectric constant reflects the soil's ability to transmit electricity — the constant increases as the water content of the soil increases. Benchmarking the dielectric constant according to this concept, water content at field capacity (the upper limit of the regime) is considered to represent 100 per cent availability of water for crop growth, while water content at the level where plants wilt (the lower limit of the regime) is considered to represent 0 per cent availability of water.
Comparative study — tomatoes and cucumbers
A project is being carried out in Abu Dhabi to compare the water requirements of traditional irrigation with those of smart irrigation technology. The overall goal is to improve the sustainability of the agricultural sector.
For each crop, the safe limit of soil water depletion (the lower limit of the regime) is determined experimentally and is taken as the criterion for triggering smart irrigation. The project uses a wireless soil moisture sensing system to measure the water content of the soil. This type of information is necessary to make good irrigation scheduling decisions — especially if a variable rate irrigation system is used.
The smart irrigation system consists of smart sensor probes installed at multiple depths. These probe arrays are linked to a solar-driven monitoring station and a radio-frequency transmitter. A sample of 200 farms has been selected from around the emirate. Water consumption is measured by fixing meters at each of the farms. The farms are classified into three categories depending on their crops: farms that cultivate vegetables, date palms and fodder; farms that cultivate date palms and fodder; and farms that cultivate only date palms.
As a proof of concept, the research arm of the Abu Dhabi Food Control Authority has implemented a pilot study on smart irrigation technology. The study, which took place from 2011 to 2013, considered two different crops (tomatoes and cucumber).
The smart irrigation system is based on soil-water balance and crop-water balance, as measured at one or more points in the field. Continuous measurement of the water content of soil indicates when irrigation water needs to be applied to prevent crop stress. The computerized scheduling of irrigation allows for the storage and transfer of data, easy access to data, and calculations to predict crop evapotranspiration.
The pilot study evaluated the efficiency of water use in the irrigation of tomatoes and cucumbers grown in greenhouses. Four different irrigation regimes were evaluated: treatment according to the Dacom intelligent irrigation system; and three levels of irrigation equivalent to 75 per cent, 100 per cent and 125 per cent of the reference evapotranspiration calculated according to the United Nations Food and Agriculture Organization (FAO) Penman-Monteith method.
The Dacom intelligent irrigation system significantly reduced the water requirements for irrigation and achieved a higher crop yield as compared with the other irrigation levels (see table).
Scaling up smart irrigation
The pilot study on tomatoes and cucumbers is part of a research and demonstration project being undertaken by the Abu Dhabi Food Control Authority to quantify the potential of precision irrigation. The project’s aim is to evaluate a wireless soil moisture sensing array for the purpose of scheduling irrigation. The goal is to maximize water productivity by optimizing crop yield and minimizing the amount of water used in irrigation.
Water use efficiency is an important agronomic factor, especially in agricultural irrigation systems and in climatic zones where a limited amount of water from the rainy season has to last for the whole growth period, as no further rainfall can be expected. The project’s purpose is therefore to evaluate tools that will enable farmers in the United Arab Emirates to make better use of their water resources.
The project uses smart wireless soil moisture sensing systems to increase irrigation efficiency. The idea is to assess the actual water requirements of crops through the use of wireless soil sensors placed in the root zones of plants at depths of up to 1.2 metres, depending on the type of plant. The sensors are used to determine soil moisture content at 10 centimetre intervals.
These data are then sent to a central computer wirelessly via satellite. The computer software displays the data graphically, which helps researchers to observe moisture levels near the plant roots. The software processes these data to determine, depending on the type of soil, when irrigation should take place and how much water should be used. The software also runs the irrigation device wirelessly.
The project timeframe is 2012–2015 and comprises three phases. During the first phase, information will be collected on the production and smart irrigation of cucumber and tomato crops (2–3 years), forage crops (2–3 years) and date palm trees (3–5 years). In the second phase (2 years), the smart irrigation system will be rolled out to mass production on farms to test its economic viability at full scale. Activities will also be expanded to evaluate the use of these technologies on the other main crops in the country, such as potato, lettuce and citrus. In the third phase, the most effective technology will be disseminated to farmers throughout the country, and the plan is to assist farmers in adopting the technology.
The benefits of smart irrigation
As a scarce resource in the United Arab Emirates, water affects all sectors of the economy. The findings from research on smart irrigation systems showed that smart irrigation is superior to traditional irrigation in terms of controlling water use and in producing agricultural outputs. Smart irrigation therefore has a beneficial effect on revenue. It increases water productivity in vegetable agriculture, increasing the return per square metre of vegetable production. It also dramatically decreases irrigation losses, which will save millions of cubic metres of water annually on a national scale. The next stage is to develop an irrigation scheduling programme for the vegetables greenhouses in the Al Ain area.
In terms of raising awareness, the results of the project will lead to a realistic appreciation of the actual consumption of water by farms for irrigation purposes. “The findings of the initiative will help us direct the farmers to use only the required amount of water so as to conserve water. The specific water needs of each crop can be identified and irrigation regulated accordingly”. This is the view of the Abu Dhabi Food Control Authority, in pursuing — among its strategic priorities — the improvement of agricultural practices and progress in the farming sector.
One of the main challenges is to get farmers to adopt smart irrigation. The response in the United Arab Emirates is twofold, involving awareness-raising by disseminating the results of research on smart irrigation, and providing education and practical support in cooperation with the Farmer Services Centre.
Once the farmers agree to adopt the smart irrigation system, they will need to be provided with specific information on the daily irrigation requirements of their crops. This will be achieved through the development of a computer or web application which will make the information available to the farmers at any time.
Another obstacle concerns how to deal with areas where soil salinity is high and water quality is low. Such areas have so far been excluded from the research, and outcomes are likely to be less good, but farmers in these areas need support. One possibility would be to use the Abu Dhabi soil mapping information and feed the web application with the most recent salinity levels in each region. These salinity levels could then be taken into account in calculating the water requirements for irrigation.
The Abu Dhabi Food Control Authority project is in line with the policy of the Government of Abu Dhabi and in particular its Agenda 2030. The policy aims to achieve the environmentally sustainable development of the farming sector, in order to guarantee food safety and food supply in the United Arab Emirates. This is in line with the national vision for sustainable agriculture, which states that “The agricultural sector is one of the country’s largest consumers of water, and this is a reflection of the management of agricultural lands and soil treatment. The increasing population, and the need to secure food for them, requires special efforts to guide the agricultural sector towards environmentally sustainable consumption of water, the correct use of chemicals and safe waste management of farms”.
Sustainable agricultural development is based on a balanced framework for developing and implementing suitable farming systems and good agricultural practices. Increasing production efficiency through modern techniques, and combining high value crops and animal wealth are essential.
The project promises to develop irrigation management guidelines based on best practices. The guidelines will provide practical information and advice that farmers can use to make, document and revise decisions relating to the design and operation of irrigation systems, to achieve sustainable irrigation.
According to the findings so far, the Dacom method shows an increase in irrigation efficiency of more than 10 per cent as compared to other scientific estimation methods, which in turn means saving millions of cubic metres of water in Abu Dhabi.