JEDDAH – Agriculture in Saudi Arabia consumes about 90 percent of the water used in the country. The efficient use of finite water resources is essential for attaining sustainability of agriculture and protection of the fragile environment in the Kingdom. Precision Agriculture Research Chair (PARC) of King Saud University (KSU) has been implementing applied research projects funded by King Abdulaziz City for Science and Technology (KACST) under the National Plan for Science and Technology (NPST) in order to develop efficient ways of utilizing water in the agriculture sector. PARC employs Precision Agriculture (PA) technologies to achieve this overarching goal. According to Dr. Khalid Al-Gaadi, Director of PARC, the science of Precision Agriculture (PA) is quite new to this region and for the first time in the Middle East, research on PA has been initiated by KSU, represented by PARC. Precision agriculture implies application of inputs such as seed, water, fertilizers and pesticides in the right amounts, at the right time, at the right place and in the right manner. PA helps farmers optimize use of inputs that results in increasing the agricultural economic efficiency and environment protection. PA involves assessment, management and monitoring of spatial and temporal variability in soil properties and crop growth parameters. In order to implement PA, cutting edge technologies, such as Remote Sensing, Geographic Information System (GIS), Global Positioning System (GPS), Information and Communication Technologies, Sensor Technologies, Wireless Sensor Networks, Yield mapping and Variable Rate Technologies (VRT) are employed. Participatory mode is being carried out on two commercial farms in Haradh and Al-Kharj regions, one of which belongs to the National Agricultural Development Company (NADEC). KSU, represented by PARC, and NADEC signed an MOU in June 2011 for undertaking collaborative research work. The PA research is carried out to implement two projects funded by KACST under NPST. These projects are — precision fertigation for sustainable agriculture in Saudi Arabia; and water productivity mapping and assessment of irrigation performance for irrigation water conservation, a study in Al-Kharj region. The main goal of both projects is to optimize the use of resources, such as water and fertilizers, in agriculture. State of the art Precision Agriculture laboratory has been established in PARC. The laboratory is equipped with most of the high-end technology instruments that are necessary to carry out the advanced PA research in the field of agriculture. PA research work is carried out on farmers' fields and not on University's educational farm. The farmers' participatory mode of work enables the integration of farmers experiences when planning the research program. Constant dialogue with the farmer is necessary to implement the projects and empower the farmers. In addition, farmers' participatory research can drastically reduce the time taken for the transfer of technology to the end-user. The principle of "Seeing is believing" is thus integrated into the research process, which is an activity that has not been reported earlier from Saudi Arabia. Dr. Al-Gaadi explained the mechanics of the precision fertigation research methodology adopted by PARC, saying that the research planning, including experimental design and various treatments, were thoroughly discussed with the farmer before the start of the field work. Agricultural operations were all carried out by the farmer. In order to vary the application rate of inputs for the test crops (wheat and alfalfa), Variable Rate Irrigation (VRI) systems custom designed by Valley Irrigation Company of California, US, were mounted on two center pivot irrigation systems. These systems were capable of varying the amount of irrigation water applied to fit the need of different parts within the field. However, the domain knowledge was necessary to develop prescription maps for the VRI systems. The prescription maps for the test crops were developed based on the amount of water to be applied in each irrigation cycle that depended on the crop evapotranspiration (ETc). These prescription maps were uploaded onto the VRI control panel for applying water differentially within the field. The decision to vary the amount of irrigation water within a field was based on the concept of Management Zones (MZ). Delineation of MZ was a novel technique which hitherto was not used in Saudi Arabia. In this technique, the field was divided into convenient Management Zones based on the spatial variability of the production potential of different field areas. The parameters that were used for dividing the field into MZ were: soil electrical conductivity, elevation of the field and composite Normalized Difference Vegetation Index (NDVI) determined using time series satellite imagery. Each of the research fields on both farms was demarcated into two MZ. Field experiments to study the response of crops to precision fertigation are currently carried out. The growth pattern, crop canopy temperature, Land Surface Temperature (LST), Leaf Area Index (LAI), Normalized Difference Vegetation Index (NDVI) and hyper spectral reflectance of both crops were constantly monitored through proximal, as well as, remote sensing techniques. Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) satellite images were procured for periodic monitoring of crop growth. ASTER is an imaging instrument onboard Terra, the flagship satellite of National Aeronautics and Space Administration (NASA), USA. In addition to satellite image analysis, periodic ground truth data on crop bio-physical parameters was also collected. Yield Monitors fitted onto hay baling units were used to record the geo-referenced hay yield of alfalfa. Based on the total quantities of water used and the hay yield obtained, the crop water use efficiencies were determined. According to Dr. Al-Gaadi, the initial results of the study are highly promising. These results have indicated that a saving in the total quantity of water of 20 percent (6260 m3 of water/ha/year) in alfalfa and 30percent (2280 m3 of water/ha/season) in wheat can be achieved without sacrificing the yield of crops. At the national level, this saving is translated into more than 775 million m3 of water per year for a total alfalfa cultivated area of 123,837 ha in 2011. For wheat, the saving is more than 439.5 million m3 of irrigation water per season considering a total wheat cultivated area of 192,818 ha during 2011 season. This substantial water saving in a scarce resource in the Kingdom is crucial and has national and strategic dimensions. This water saving in irrigation water was achieved by the adoption of the Precision Fertigation (PF) techniques. The quantity of diesel used for running a center pivot (1,360 gallons per minute) for one hour is around 90 liters. Considering the present diesel cost of SR0.25/lit, the cost of running the pivot works out to SR22.5 /h. For alfalfa, a saving of SR456/ha can be achieved in a period of eleven months due to saving of water alone. However, the saving for wheat is calculated at SR166/ha/season, where the season is about 4 to 5 months. At the national level, it can be extrapolated that a saving of about SR56.5 millions can be achieved considering a total alfalfa cultivated area of 123,837 ha during the year 2011. For wheat, this saving is a little more than SR32 millions considering a total area of wheat of 192,818 ha in 2011. The savings can effectively help farming enterprises increase their profitability and attain sustainability while protecting and preserving the environment. The overriding importance of water to the country's food and water security can make these economic benefits seem invaluable. PARC is also engaged in developing maps of crop types, crop productivity, Evapotranspiration and Crop Water Productivity. The third ambitious project on "Use of saline water for tomato production in hydroponic green houses" has already been approved to be funded by NPST and will be started soon. The efforts of PARC team would go a long way in developing suitable precision agriculture technologies for the benefit of the people of Saudi Arabia. — SG
