Hydroponics is a method of growing plants without soil where plants are fed using a nutrient solution. The plants are supported in various substrates such as rock wool, expanded clay aggregate, gravel, sand, or coir peat. Since most hydroponic methods employ some type of growing support these methods are often referred to as “soilless culture”, while water culture alone is true hydroponics.
Hydroponics as an alternative to traditional soil-based farming has ramped up. For instance, as of 2017, Canada had hundreds of acres of large-scale commercial hydroponic greenhouses, producing peppers, tomatoes, and cucumbers. Greenhouse production is becoming more economically feasible in the United States with production focusing on artesian and romaine lettuce, Beef Steak, and cherry tomatoes. Vegetables grown in a greenhouse are often of higher quality and have been grown with reduced or no pesticides. Additionally, yields can be 5x as much lettuce per acre than in a field. The United States hydroponic revenue has been estimated to reach $607 million with an annual growth rate of 3.6% over the last five years.
Commercial growers are utilizing two hydroponic methods, continuous-flow solution culture and static solution culture. Nutrient Film Techniques (NFT) is a variation of the continuous-flow method. It uses a circulating hydroponic system that utilizes plastic channels to grow plants. This works best for leafy greens such as lettuce or herbs. NTF provides a clean growing environment. The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen, and nutrients. NFT can be suspended vertically as in the picture below. This setup is at the heart of vertical farming.
In static solution culture, plants are grown in containers of nutrient solution, such as plastic buckets, tubs, or tanks. The solution in which the plant roots are suspended is usually aerated. A hole is cut in the lid of the reservoir for each plant. A single reservoir can be dedicated to a single plant, or to various plants. Reservoir size can be increased as plant size increase. A large scale “raft” static solution system is shown below.
Despite the technological developments that have improved our agriculture productivity, the main issues of land availability, seasonality, high water demands, and carbon emissions seem like insurmountable facts. These long-standing obstacles continue to prevent us from meeting sustainability and food security goals. Therefore, in order to increase agricultural output to feed an ever-increasing human population requires the implementation of new farming practices, with a focus on hydroponics. The science and technology is not that complicated. Nutrients are constantly monitored by computer systems leading to better yields using fewer pesticides, herbicides, fungicides.