Comparative evaluation of nutrient, land, water and energy requirements of hydroponic vs. conventional agricultural methods: Case study for lettuce, basil, and arugula

Abstract

The rapidly growing world population needs more environmental resources, mainly water and food, to the limit of extinction and defunctionalize traditional solution methods. Available water resources are decreasing day by day, moving to a value below the previously determined rate in researches as 3%. The most powerful reason for this is the increase in the carbon footprint created by industrialization. Global warming, changes in climate lead to insufficient water and food resources for the existing population. The amount of water per capita in year for our country is around 1500 m3, this amount is projected to decrease to 1.100 m3 in 2030. In this direction, efforts to prepare watershed protection action plans including long term conservation programs and measures to protect water resources for all types of use, prevent pollution, improve the quality of contaminated water resources, as well as project works to effectively use the community water resources by reducing losses and leaks in the water supply system have been initiated. Using water resources in our country general directorate of state water works for irrigation datas, other water use datas based on Turk Stat in Turkey as of 2016, 71,3% of the water in agricultural irrigation, 18,4% in industry, 10,3% in drinking and using water was determined. Based on these datas, it is concluded that the amount of agricultural irrigation should be under more controlled, considering the percentage of agricultural water use. In agricultural irrigation, 70% surface, 17% sprinkler, 13% drip irrigation methods are used. New method is used as an another alternative to conventional agricultural food production and also other modern greenhouse food production as the amount of water usage, more efficiently by 95% called "hydroponic farming" technology of food production simultaneously in both climate commitment reduction, reducing production time, while eliminating the problem of transportation into the city in conformance with the installation, reduce your carbon footprint. Dissolved nitrogen (N) and phosphorus (P) are the two main elements that trigger eutrophication. When the elements are above the limit concentrations, it is the result of water pollution and threatens aquatic life. As a result of uncontrolled fertilization in traditional agriculture, these pollutants, which are mixed into the soil release through irrigation water and then into groundwater, threaten the available water resources and the aquatic ecosystem. In the hydroponic vertical farming method, on the other hand, the amount of water used is reduced and fertilizer is used as much as the plant needs, so that there is no uncontrolled release into natural water resources. Comparative evaluation researches of plants grown in a controlled environment have proven that the plant is able to retain more nitrogen and phosphorus. Plants grown in hydroponic agriculture are healthy and nutritious for human health and consumption, while at the same time reducing the higher amount of nitrogen and phosphate in the water. Hydroponic farming systems are agricultural production methods made with only water without using soil. Plants get the minerals they need from the water in a usable form. The effects of technology on agriculture have reached to the inclusion of mechanization in time, then the development of sensor technologies, and finally the automated soilless vertical farming systems in the closed area, where lighting and air conditioning technologies can be realized by replicating nature. Vertical agricultural products, in which almost all leafy greens and some fruits can be grown, are nutritious in terms of content and can be grown in a shorter time. If the plants are grown in these systems, need much less nutrient use, can be carried out indoors and with automation systems, then the compliance of the plants grown with the increasing food requirement and the principle of "food safety and sustainability" is determined. Since the importance of growing indoors will be independent of the effects that may come from outside, chemicals used for pests are not required in these systems. With the development of lighting technologies, sunlight that will operate the photosynthesis mechanism of plants can also be imitated in these systems. The light spectra required by the plant vary at different rates depending on the type of plant. For the most efficient lighting, plants can be tested continuously and the highest yield can be given at any time of the year with full commitment. With advanced technology; automation systems, air conditioning, lighting, dosing, circulation and disinfection processes are monitored by sensors. In addition, the high quality tastes and images of fruits and vegetables grown hydroponically are better quality since the products grown in traditional agriculture are generally used both chemical usage and stress factors such as wind, irregular nutrients distribution and raining. However, in the literature, the nutrient and oil content of plants can be changed without affecting their naturalness by changing the ambient conditions given. Based on studies in literature, it is planned to prepare a thesis that can be examined under the title of Environmental Biotechnology within the scope of the hydroponic system consuming 95% less water compared to traditional agriculture within the principle of sustainability; examining nitrogen, phosphorus and energy consumption; obtaining quantity and plants are grown faster and under the principle of higher yield compared to the climate and arable area problems encountered in traditional agriculture. The aim of the thesis is to realize the reuse of wastewater, higher nitrogen and phosphorus consumption, energy consumption and area usage in the hydroponic system in Gebze Technical University (GTU) Institute of Biotechnology in collaboration with Plant Factory Inc. In the thesis, the prototype installed by Plant Factory Bitki ve Gıda Sistemleri A.Ş. at GTU, Biotechnology Institute; trials of automation will be carried out in which plants will grow in suitable conditions, healthy, higher yield plants. Generally, there are hydroponic studies with lettuce, basil and arugula plants in the literature. The contribution of the study to the literature is a more comprehensive examination of five parameters, in five different experiments, in four different experimental area, with three different leafy greens in a single study. In the study, energy, area, nitrogen, phosphorus and water consumption results were obtained by using three soil experiments and two hydroponic experiments (nutrient film technique, deep water culture) in open field (OF), greenhouse (GH), growth chamber (GC) and container (C) experimental areas that were carried out simultaneously with lettuce, basil and arugula plants. According to the datas obtained from the growing conditions, the nitrogen and phosphorus consumption rates in the hydroponic "Nutrient Film Technique (NFT)" and the "Deep Water Culture (DWC)" experiments are higher than soil agricultural studies. As plants grow, the growing medium only acts as a carrier for nutrients. For this reason, the environment of plants in traditional agriculture is soil, while hydroponic systems' is water, so plants take nutrients and transport them to tissues faster. In this case, because of providing homogeneity in water faster; homogeneous growth of plants is higher than soil agriculture by the way. Hydroponic systems are supportive alternative to traditional agriculture for efficient use of water in addition to efficient nitrogen and phosphorus consumptions. In the study conducted with NFT, it was observed that the water consumption rates were the lowest was more higher than others followed by DWC. High area use efficiency can be achieved successfully with the NFT hydroponic system in plant cultivation followed by DWC. In addition to that, another reason for the different responses of grown plants to different environmental conditions is the positive effect of lighting technology on plant growth. In addition, the importance of climatic conditions for the plant is as valuable as the lighting technology. As a result of the temperature and humidity conditions being adjusted where the plant does show required stress conditions to balance both the root and upper parts of the plant under the effect of transpiration and photosynthesis. The amount of energy consumption, which is another parameter obtained from datas, calculated as per gram dry leaf weight, is from low to high, respectively; in soil-based experiments as OF, GH, GC experimental areas; in hydroponic studies, NFT, DWC systems. NFT consumes less energy than the DWC hydroponic system but more than greenhouse production. In today's conditions, energy is provided from fossil sources. For this reason, although the carbon emission rate due to transportation is much less than traditional agriculture with its establishment in city centers, the energy used during production, especially due to lighting technologies, is quite high. Renewable technologies should be used to prevent energy-related carbon emissions. Solar, geothermal, wave, wind, biomass, hydroelectric, hydrogen energies are among the renewable energy sources that can be used. Considering the advantages and disadvantages, indoor hydroponic systems in green leafy plant cultivation is considered as an alternative method to support soil agricultural methods, both in terms of water, area, nitrogen-phosphorus use efficiency and the yield per square meter area.