The key to the indoor hydroponic system is undoubtedly the formula of the nutrient solution, which mineral elements the plants need, and the concentration at which the plants can absorb it are all questions that need to be answered when preparing the nutrient solution. From the famous willow experiment in the 16th century, plant physiology has undergone development for centuries. Plant physiologists have divided the nutrients necessary for growth and development absorbed by plant roots into a large number of elements and trace elements. A large number of elements are nitrogen, phosphorus, and sulfur. , Potassium, calcium, magnesium, silicon, these elements are elements required by plants, so common artificial fertilizers are mostly nitrogen, phosphorus and other fertilizers; trace elements include iron, manganese, zinc, copper, molybdenum, chlorine, sodium, Nickel, etc. These mineral elements exist in the form of mineral ions and are absorbed by plant roots.
With the exception of carbon, hydrogen, and oxygen, all nutrients necessary for plant growth are absorbed into the plant by the roots. Although plants differ in the amount of macroelements and microelements required, they are all essential nutrients, each of which plays a unique role in plant growth. The lack of any element will affect the normal development of plants. Different plants have different manifestations of lack of mineral elements. The side dish of basil in three cups of chicken is a common hydroponic cultivation crop in a plant factory. Dr. Neil Mattson and Tanya Merrill of Cornell University in the United States have relatively complete the deficiency The comparative experiments show that the lack of each mineral element will cause diseases to plants:
The lack of nitrogen fertilizer will lead to yellowing of old leaves and smaller plants;
Lack of phosphate fertilizer causes purple spots to appear on old leaves, long-term phosphorus deficiency causes purple spots to expand, leaves lack green, and plants flower early;
Potassium deficiency will cause necrosis of the basil leaves, and the leaves turn yellow;
Calcium deficiency leads to necrosis of the young leaves and yellowing of the roots;
Lack of magnesium will cause leaf lack of green, and further deterioration will cause leaf necrosis;
Sulfur deficiency will cause the whole leaf to turn yellow, and the growth of the plant will be significantly reduced;
Long-term iron deficiency will cause green deficiency symptoms in the young leaves first;
Boron deficiency can lead to a lack of green leaves and inhibited root growth.
Obviously, the preparation of nutrient solutions requires repeated experiments to adjust the concentration of various mineral elements. For different types of crops, or different varieties of the same crop, special nutrient solutions are prepared, and even the same variety of crops have different mineral levels during different growth periods There will be differences in nutritional needs. In addition, all kinds of mineral ions are dissolved in the nutrient solution, and the total ion concentration and pH of the nutrient solution must be controlled within the range suitable for plant growth. This must take into account the chemical reaction and solubility between the various ions.
If it is said that advanced technical equipment provides a solid hardware foundation for the operation of plant factories, then the nutrient solution formula and light formula are the most important technical backing for plant factories to achieve efficient and high-quality production. The plant factory of Zhonghuan Yida has customized nutrition formulas for plants when cultivating different varieties of fruit vegetables and leafy vegetables, ensuring that the different needs of different crops for mineral nutrition are met one by one, thereby achieving efficient production.
The Central Yida plant has nutrient solutions for different crops.
Nutrient solution circulation and control system in plant factory:
Hydroponic cultivation of a plant is simple, but it is different for hundreds or thousands of plants: during the industrial production of hydroponic crops, it is not practical to change water regularly, and during the cultivation process, it may be in the nutrient solution. The algae produced and the toxic substances metabolized by the plant itself will inhibit the growth of the plant, and the properties such as the concentration and pH of the culture medium will also change as the plant absorbs water and nutrients. These factors bring challenges to hydroponic cultivation in plant factories.
At present, the nutrient solution circulation and control system is a very important water and fertilizer control system in a plant factory. It is a technology that recycles the remaining nutrient solution after the plant is used. Automated control.
Intelligent plant nutrient solution circulation control equipment is used in the plant factory of the Central High-Tech Yellow River Delta Agricultural High-tech Industrial Demonstration Zone Project.
The nutrient solution circulation control system mainly includes cultivation beds, nutrient solution tanks, detection sensors, circulating water pumps, filtration and disinfection devices, and automatic control devices.
The nutrient solution in the nutrient solution pool is monitored by a detection sensor to ensure that its ion concentration, pH, oxygen content and temperature are in a range suitable for plant growth. The ion concentration and pH are adjusted by adding a prepared nutrient solution mother or acid-base solution. The increase of the oxygen content is through the circulation of the stirring device or the culture liquid, and the liquid temperature is performed through the heating or cooling device.
The nutrient solution is pumped into the cultivation bed by a pump, and the excess nutrient solution is filtered and sterilized and reflowed into the nutrient solution pool. This is the nutrient solution circulation process.
Indoor Hydroponic System
Optimization of hydroponic system:
The nutrient solution circulation control system realizes the full use of water and nutrients, and avoids environmental pollution caused by the discharge of nutrient solution waste liquid to the outside world. It not only saves resources, but also has the characteristics of environmental friendliness. However, the current nutrient solution circulation control system still has room for optimization.
Although the recycling of nutrient solution saves resources and protects the environment, the organic acids and other substances secreted during plant growth and metabolism are not good for plant growth. This makes the accumulation of harmful substances in the nutrient solution circulating fluid. Removing these harmful substances is extremely beneficial to the realization of nutrient solutions Recycling.
At present, the most suitable method is the photocatalytic method, which uses the strong oxidizing effect of special materials nano-titanium dioxide to absorb ultraviolet light, and decomposes organic acids in nutrient solutions into carbon dioxide, water and other small molecules. The photocatalytic method has been widely used in the purification of environmental pollution, and the application in the purification of nutrient solutions is still in the research stage. This method is not only efficient and non-toxic, but also has no effect on the quality of vegetables. Method of nutrient solution purification.
The growth process of plants cannot be fully quantified. Just as "there are no two identical leaves in the world", each round of crop growth will cause different changes in the composition of the nutrient solution, although the concentration and pH of the nutrient solution can be real-time Monitor and make regulatory decisions accordingly, however, the detection of a single nutrient element still cannot be monitored in real time.
With the continuous development of sensing technology in the agricultural field, the detection technology of single nutrient elements is also in the stage of rapid development. Maybe in the near future, the single-nutrient element real-time detection technology can be applied to the nutrient solution circulation control system. When a crop grown in a plant absorbs more of an element, it can detect the rapid decrease in the concentration of the element in time, and then increase the dose of this element in the nutrient solution.