Hydroponics is a new type of soilless cultivation of plants, also known as nutrient solution culture. Its core is to directly soak the roots of plants in nutrient solution. This nutrient solution can replace soil and provide plants with water, nutrients, oxygen, etc. Growth factors enable plants to grow normally.
In the soil, organic matter is decomposed by soil microorganisms and animals, and transformed into mineral nutrients needed for plant growth. The water in the soil dissolves these mineral nutrients (usually in ionic form) so that they can be absorbed by the roots of plants. In order for plants to obtain balanced nutrition, the various substances in the soil must meet the optimal ratio. Unfortunately, such soil is very rare in nature.
After adopting hydroponics, plants can directly absorb the nutrients and water in the nutrient solution through the roots, and people can manually prepare a nutrient-balanced solution to achieve a balanced “diet” of the plant, which is obviously much easier than finding the soil. Because these solutions are all contained in containers, they can be recycled and will not flow into the soil to affect the environment, and are safe, reliable and sustainable.
Common methods of hydroponics
There are four common hydroponic technologies, each of which has its own advantages and disadvantages, and has a relatively large number of practical production applications. Each method has some variants, but most of them are inseparable.
- Deep Flow Technique, referred to as DFT (Deep Flow Technique)
- Nutrient Film Technique, referred to as NFT (Nutrient Film Technique)
- Floating Capillary Hydroponics cultivation technology, referred to as FCH (Floating Capillary Hydroponics)
- Spray culture technology, also known as spray culture, aeroponics (Aeroponics)
Deep Flow Technology DFT
It is mostly used in facility agricultural planting such as early-built plant factories and greenhouses.
The advantages of DFT are:
- Hanging cultivation. The plant is suspended on the planting plate, part of the root system is inserted into the nutrient solution, and part of the root system is aerial in the gap between the nutrient solution level and the planting plate. It has the nature of semi-hydroponic and semi-aerial culture, and it is easier to solve the water-gas contradiction of the root system.
- The liquid layer is deep. The root system stretches into the deeper liquid layer, and a single plant occupies a lot of liquid. Due to the volume and depth of the liquid, the concentration of the nutrient solution (including total salt and nutrients), dissolved oxygen, pH, temperature, and moisture are not prone to drastic changes, providing a stable growth environment for the root system. This is the outstanding advantage of deep flow hydroponics.
- The nutrient solution circulates. The circulation of the nutrient solution can increase the dissolved oxygen content in the nutrient solution; eliminate the local accumulation of harmful metabolites on the root surface (the most obvious is the physiological acid-base); eliminate the nutrient concentration difference between the root surface and the extra-root nutrient solution, so that the nutrients can be Send it to the root surface in time to more fully meet the needs of the plant; promote the re-dissolution of nutrients that have become ineffective due to precipitation to prevent the occurrence of nutrient deficiency. Therefore, even if it is cultivated marsh plants or plants that can form oxygen transport tissue, it is necessary to circulate the nutrient solution.
- There are many types of crops suitable for cultivation. Except for root and tuber crops, almost all fruit vegetables and leafy vegetables can be cultivated.
Disadvantages: the initial investment is large, the nutrient solution is large and the load is high, and it is difficult to realize three-dimensional cultivation.
Nutrient Liquid Membrane Technology NFT
It is mostly used in new plant factories built. In 2016, the world’s largest plant factory built by Zhongke San’an uses a new modular cultivation device to realize the three-dimensional planting of NFT.
Advantages of NFT:
- Less investment in facilities, easy and convenient construction. The NFT planting trough is made of lightweight plastic or spliced with corrugated tiles. The structure is light and simple, easy to install, easy to disassemble, and low investment cost.
- Intermittent liquid supply, the liquid layer is shallow and flowing. The nutrient solution layer is shallow, and the roots of the crop are partially immersed in the shallow nutrient solution and partly exposed to the moisture in the planting trough, and the shallow nutrient solution circulates, which can better solve the oxygen demand of the root respiration.
- It is easy to realize the automatic management of the production process.
Disadvantages: Affected by power supply, high requirements on electromechanical and production management.
Floating board capillary cultivation technology FCH
FCH is a new type of soilless cultivation system developed by Zhejiang Academy of Agricultural Sciences and Nanjing Agricultural University in 1991 with reference to the Japanese floating root method.
Advantages of FCH:
- Cultivate moist roots, create an oxygen-rich environment, and improve root oxygen supply conditions. Part of the root system floats on the wet felt of the floating board in the tank, which is relatively thick and short, which can absorb oxygen in the air and play a role in improving the oxygen supply of the entire root system; part of the root system grows in the nutrient solution, which is relatively slender and mainly absorbs nutrients And moisture. This overcomes the problem of easy hypoxia in the rhizosphere environment of the DFT system.
- The supply of nutrient solution is stable, not afraid of short-term power outages. The nutrient solution of the planting tank can generally be maintained at 3-6cm. During the cultivation process, temporary water interruption, power outage, or water pump or timing failure occurs, resulting in the failure of normal liquid supply, which has no major impact on the normal growth of plants.
Disadvantages: Since the root system can grow into the wet mat of the floating board, the reusability of the device is poor and the operating cost is high.
Aerosol culture, also known as aerosol culture or aerosol culture, is the use of filtered nutrient solution under pressure to atomize the nutrient solution into fine droplets through an atomizing spray device, which are directly sprayed to the roots of plants to provide the needs for plant growth. A soilless cultivation technique that contains water and nutrients.
Advantages of spray culture:
- It can well solve the problem of root oxygen supply, and there will hardly be the phenomenon of poor growth due to lack of oxygen in the root system.
- The utilization rate of nutrients and water is high, and the nutrient supply is fast and effective.
- It is easy to realize three-dimensionality, can make full use of the space in the greenhouse, and increase the planting quantity and output per unit area. The use of greenhouse space is 2 to 3 times higher than that of traditional flat cultivation.
- It is easy to realize the automation of cultivation management.
- The investment in production equipment is large, and the reliability of the equipment is required to be high, otherwise it is easy to cause problems such as nozzle blockage, uneven spraying, and excessive droplets.
- In the process of planting, the concentration and composition of the nutrient solution are prone to large changes, so the management technology requirements are higher.
- In the case of a short-term power failure, the spray device cannot operate, which can easily cause damage to plants.
Application of hydroponicsedit
(1) Used for hydroponic vegetables
Cultivating pollution-free green food, health and safety, is deeply valued by people.
(2) Used for hydroponic flowers
Hydroponic flowers have the advantages of cleanliness and sanitation, convenient maintenance, etc., which are especially suitable for indoor decoration and are deeply loved by consumers.
(3) Used for cultivating medicinal plants
Many medicinal plants are root plants, and the root growth environment is very critical. Hydroponics, especially spray culture, can provide a good growth environment for the roots of medicinal plants, so the planting effect is very obvious.
Advantages of hydroponic vegetables
- The products are of good quality, safe and hygienic.
Leafy vegetables mostly eat the stems and leaves of plants, such as lettuce, chicory and other leafy vegetables are mainly eaten raw, which requires the products to be fresh, clean, and pollution-free. Spei vegetables are easily contaminated by parasites and bacteria, soiled and inconvenient to clean. However, hydroponic leaf vegetables are of better quality than soil cultured leaf vegetables, clean, fresh and tender, with good taste and high quality. Can be eaten directly.
- It can be quantified in the plant factory.
Leafy vegetables are not easy to store, but in order to meet market demand, annual production is required. Soil cultivation of leafy vegetables requires cumbersome operations such as soil preparation, planting, fertilization, and watering. However, soilless cultivation is very simple. You only need to plant seedlings in the planting holes, and annual cultivation can be carried out on the same site. For example, lettuce can be sown, planted, harvested every day of the year, and produced continuously without interruption. Therefore, the hydroponic method is convenient for cropping arrangements and is suitable for planned and contracted production.
- Regardless of low and peak seasons, it is less affected by the natural environment.
Leafy vegetables generally have short plants, and there is no need to increase support facilities, so the facility investment is less than that of fruit vegetables. Hydroponic vegetables have a short growth cycle and quick turnover. The hydroponic method is also a facility production, which grows in a greenhouse and is generally not easily damaged by typhoons. Farmers who can supply fresh vegetables during the typhoon season in coastal areas can often get higher profits.
- Save fertilizer, no need to replace nutrient solution midway.
Leafy vegetables have a short growth cycle. If there are no major physiological diseases in the middle, generally only one nutrient solution needs to be prepared from planting to harvest, and no nutrient solution needs to be replaced in the middle. Fruits and vegetables have a long growth period, even if there is no major physiological disease, in order to ensure the nutrient balance of the nutrient solution, it is necessary to renew the nutrient solution in half or full.
- High economic efficiency. Hydroponic leafy vegetables can avoid continuous cropping obstacles, and the multiple cropping index is high. The facility operation rate is as high as 20 crops a year, and the production economic benefits are high.