• Soilless Culture (Hydroponic) (Soilless culture /Hydroponic) is a system of growing plants in substrate media (without soil) solid/liquid/foggy medium. So, the plant is fed by using a solution that contains nutrients (diluted liquid fertilizer), where the plant roots are supported with organic or inorganic solid materials (organic - peat moss, cocopeat, etc.), or inorganic (volcanic tuff - tuff, perlite, etc.). Hydroponic system works better with roots that do not have to search for nutrients deeply into the soil. Soilless culture and hydroponic techniques are considered promising agricultural techniques in the future because they have many benefits, the most important of which is increasing water productivity (saving in the amount of water used in irrigation), increasing crop yield per unit area, and the possibility of growing crops in any environment other than soil, regardless of location (e.g. urban areas).

• Controlled Environment Agriculture (CEA) CEA is the technique of growing plants in a precise and comprehensive controlled environment using LED lighting. This technology is applied in closed spaces (or containers). The operational environmental conditions such as temperature, humidity, carbon dioxide concentration, provision and control of artificial lighting, provision of nutrients and control of pests and diseases are regulated and monitored. This technology aims to improve plant growth conditions and increase crop production, allowing plants to be grown throughout the whole seasons. Such innovative methods of agriculture come in response to the urgent need to address climate change effects, conserve water resources, reduce pollution, and increase food production more efficiently. By utilizing modern technology, such as the Internet of Things (IoT), the environment surrounding plant growth within CEA units can be controlled to achieve optimal results and meet global food needs. The CEA system is characterized by its ability to achieve up to five times the productivity compared to traditional agriculture with the same cultivation area, and consumes approximately 80% less water compared to traditional agriculture. These advantages play an important role in facing global challenges such as increasing food demand and climate change challenges. The CEA is considered a part of the smart farming systems, where environmental conditions can be precisely controlled to produce crops outside the traditional growing seasons. For this reason, experts and farmers are moving towards adopting these new technologies, including the Internet of Things (IoT) and artificial lighting (LED light). Hydroponic systems are widely used in the controlled environment agriculture, where plants are grown in a nutrient solution contains the nutrients needed for plant growth. This leads to increased crop production and improved quality. Soilless farming techniques (hydroponic) are considered smart agricultural techniques that work to increase water use efficiency. Using these techniques saves 50% (in field crops) and 70% (in leafy crops) of the water used in producing the same crops compared to traditional agriculture. While the percentage of water savings used in CEA techniques reaches more than 80%. Despite its many benefits, CEA faces challenges including high equipment and maintenance costs, technical challenges, and requires a high level of expertise. However, this technology remains an important option for achieving sustainable agriculture and increasing efficient food production in our current era.

• Vertical Farming It is a modern agricultural approach that includes growing plants within a specific environment characterized by a vertical arrangement, where plants are grown in multiple vertical shelves instead of horizontal expansion as in traditional agriculture. This approach is often provided in a contained environment, such as greenhouses, and using hydroponic systems.

• Open systems in soilless agriculture and hydroponics In these systems, the nutrient solution is used only once, which reduces the spread of diseases associated with the nutrient solution, such as fungal diseases, but increases costs.

• Close systems in soilless agriculture and hydroponics These are systems in which the nutrient solution is reused repeatedly, which reduces costs but increases the possibility of the spread of diseases. In large economic projects, the nutrient solution can be sterilized (by ozone or ultraviolet light) to eliminate pathogens.

• Nutrients Solution It is irrigation water with rich nutrients (fertilizers). It is used to feed plants in soilless culture and hydroponic systems (contains all the nutrients necessary for plants). The nutrient solution must contain all nutrients except carbon, which the plant takes in from the air. The nutrient solution contains macronutrients such as Nitrogen, Phosphorus, Sulfur, Potassium, Calcium, and Magnesium, as well as micronutrients including Iron, Chlorine, Manganese, Boron, Zinc, Copper, and Molybdenum.

• pH It is the measurement that determines whether a liquid is acidic, basic, or neutral. Solutions with a pH of less than (7) are considered Acidic solutions, while liquids with a pH higher than (7) are considered Alkaline solutions (bases), while those with a pH of (7) are considered Neutral solutions. The pH of the nutrient solution affects the availability of nutrients to the plant, so it must be maintained in the optimal range. The best pH range for solutions nutrient used in soilless farming when it is between 5.5 to 6.5. In this pH range, nutrients are readily available to plants.

• Substrate media It is an agricultural medium that used to support the plant. Its most important characteristics are that it is inert, unable to react with nutrients, has the ability to retain moisture, and has good ventilation and good drainage.

• Deep Water Culture-DWC In this system, plants float on a basin of nutrient solution using polystyrene plates. Oxygen is provided by a continuously operating air pump. DWC systems can be easily set up in wood or metal frame ponds, plastic boxes, concrete ponds, or drilled ponds covered with plastic strips. Because the plants are floating and are constantly in contact with the nutrient solution, there is no risk of damage to the plants if the power is switched off or the air pump stops accidentally.

• Nutrient Film Technique (NFT) It is a nutrient solution cultivation technique in which a very shallow nutrient solution (film) containing all the dissolved nutritional elements necessary for plant growth is recycled over the exposed roots of plants in watertight plastic channels designed with a specific slope (1% -1.5%) so that it flows through which the nutrient solution. The excess nutrient solution drained from the end of the channels is collected in a collection tank and then pumped back into the channels after adjusting the pH and EC.

• Hydroponic Tower It is one of the vertical farming techniques. Plants are grown in towers of height ranging from 2.0 m - 3.0 m, and may increase. What distinguishes it from other techniques is its ability to accommodate a larger number of plants compared to other hydroponic farming techniques. The agricultural tower is fed with the nutrient solution from the top using a pump, then the excess nutrient solution is collected and reused again.

• Aeroponic system It is the cultivation of plants in an air (mist) environment, and this is done through mist sprinklers (micro- sprayer) inside a closed basin. This system is very similar to the DWC system, with the difference in the process of feeding the plants. This technology allows for more efficient use of water. The roots of plants with an aerobic system grow suspended in the air, so they receive abundant amounts of oxygen, which in turn increases the efficiency of this technique.

• Substrate media systems (Drip irrigation Systems) These are the systems in which plant roots grow in a group of inert agricultural media (organic and inorganic), replacing the soil. Their function is to provide mechanical support to fix the plant. This technology relies on the use of a feeding network (irrigation network). To feed plants properly by scheduling irrigation to manage agricultural crops, closed systems are usually used in this technology, with the possibility of using open systems for some crops, and this depends mainly on the quality of the water and the type of crop. Several techniques fall under these systems, namely agricultural trenches, Dutch buckets, and the grow slabs.

• Green Walls They are vertical structures containing different types of plants. Green walls are often planted in a growing medium consisting of a soil replacement growing medium (volcanic stone) or a nutrient solution. Since the walls contain live plants, they have built-in irrigation systems. It can be installed externally or inside homes to add an aesthetic touch.