Hydroponics refers to the cultivation method in which the root of the plant is directly in contact with the nutrient solution without using a substrate. The earliest hydroponics is to immerse plant roots in nutrient solution. In this way, oxygen deficiency occurs, which affects root respiration and causes root death in severe cases. In order to solve the problem of oxygen supply, British Cooper proposed the hydroponic method of nutrient liquid membrane method in 1973, referred to as "NFT". Its principle is to make a layer of very thin nutrient solution (0.5-1 cm), which continuously circulates through the roots of the crop, ensuring continuous supply of crop water and nutrients, and continuously supplying fresh oxygen to the roots. The NFT method cultivates crops, and the irrigation technology is greatly simplified. It is not necessary to calculate the crop water requirement every day, and the nutrient elements are supplied in a balanced manner. The roots are isolated from the soil to avoid soil-borne diseases and to eliminate soil disinfection.
Hydroponic vegetable refers to the vegetable that is cultivated under the traditional soil cultivation form, in which most of the roots are grown in the layer of nutrient solution and liquid, which only provides water, nutrients and oxygen through the nutrient solution. Hydroponic vegetables have a short growth cycle and are rich in vitamins and minerals essential to the body.
Cultivar:
Hydroponic vegetables are the most common leafy vegetables, which are easy to manage: lettuce, fungus, water spinach, purple back, leaf beet, bitter, Jingshui, and watercress. In addition to some leafy vegetables, there are also some fruits and vegetables that can also be hydroponically cultivated, such as cucumber, melon, and tomato.
Matrix cultivation is one of the most popular ways to promote soilless cultivation. It is to fix the roots of crops in an organic or inorganic matrix and supply crop nutrient solution by drip irrigation or trickle irrigation. The cultivation substrate can be placed in a plastic bag or placed in a cultivation ditch or tank. The nutrient solution cultivated in the substrate is not circulated, and is called an open circuit system, which can prevent the disease from spreading through the circulation of the nutrient solution.
The matrix cultivation buffering ability is strong, there is no contradiction between water, nutrient and oxygen supply, and the equipment is simpler than hydroponics and mist culture, and even does not need power, so the investment is small, the cost is low, and it is commonly used in production. Based on the current situation in China, substrate cultivation is one of the most practical ways.
Three-dimensional cultivation is also called vertical cultivation and soilless cultivation. This cultivation is carried out in a space by cultivating the pillars that are erected in the surrounding area or stratified by vertical gradients in the form of trusses and hangings without affecting the plane cultivation. Make full use of greenhouse space and solar energy to increase land utilization by 3 to 5 liters, which can increase production per unit area by 2 to 3 times.
Soilless cultivation focuses on the entire large agricultural system because of its light matrix. It includes the breadth of agriculture, that is, the biological function dimension; the depth of agriculture, that is, the dimension of resource development; the height of agriculture, that is, the economic value-added dimension. It is not a generally intuitive three-dimensional agriculture, but a concept of economics, similar to the current concept of "circular economy."
The characteristics and functions of three-dimensional agriculture are concentrated in four aspects. One is ¡°intensive¡±, that is, intensive management of land, reflecting the overall benefits of technology, labor, material and capital; second, ¡°efficient¡±, that is, full exploitation of land, The potential of natural resources such as light energy, water source, heat, etc., while improving the utilization rate and utilization efficiency of artificial auxiliary energy; the third is ¡°sustained¡±, that is, reducing the residues of harmful substances, improving the quality of the agricultural environment and ecological environment, and enhancing the stamina of agriculture. Continuously improve the productivity of land (water); Fourth, "safety", that is, product and environmental safety, is reflected in the use of multi-species combination to simultaneously complete the restoration of contaminated soil and agricultural development, and establish a view of economic and environmental integration.
In short, the development of three-dimensional agriculture and its unique role can fully exploit the potential of natural resources such as land, light energy, water and heat, improve the utilization rate and utilization efficiency of artificial auxiliary energy, alleviate the contradiction between people and land, and alleviate food and economic crops. The contradiction between vegetables, hazelnuts, and feeds, and the improvement of resource utilization rate, can fully utilize the space and time, and through the intercropping, , mixed crops and other three-dimensional breeding, polyculture and other three-dimensional mode, Larger increase in material yield per unit area, thereby alleviating the contradiction between supply and demand of food; at the same time, increasing the utilization rate of artificial auxiliary energy such as chemical fertilizers and pesticides, and alleviating the pressure of residual fertilizers, pesticides, etc. on soil environment and water environment Force, adhere to the "win-win" environment and development, and establish a harmonious view of the economy and the environment.
The fog culture is also called gas increase or fog gas culture. It compresses the nutrient solution into an aerosol and sprays it directly onto the roots of the crop. The roots are suspended inside the space of the container. A polypropylene foam board is usually used, which is drilled at a certain distance to grow the crop in the hole. The two foam boards are diagonally formed into a triangle to form a space, and the liquid supply pipe passes through the triangular space to spray onto the suspended root system. It is usually sprayed for a few seconds every 2-3 minutes, and the nutrient solution is recycled, while ensuring sufficient oxygen in the roots of the crop. However, the cost of this method is too high, it requires a lot of power, and there is no power outage. There is no room for buffering. It is only limited to scientific research applications. It is not used for large-scale production, so it is best not to use this method. This method cultivates the plant mechanism with hydroponics, so the root condition is the same as hydroponics.
Fish and vegetable symbiosis is a new type of compound farming system. It combines aquaculture and hydroponic cultivation, two completely different farming techniques, through scientific design to achieve scientific synergy, so that fish farming can be replaced without water. There is no water quality problem, and the ecological symbiosis effect of growing vegetables without fertilization. In traditional aquaculture, as the fish's excrement accumulates, the ammonia nitrogen in the water increases and the toxicity gradually increases. In the fish-and-vegetable symbiosis system, the aquaculture water is transported to the hydroponic cultivation system, and the microbial bacteria decompose the ammonia nitrogen in the water into nitrite and nitrate, which are then used as nutrients for utilization. Since hydroponic and aquaculture techniques are the cornerstone of fish and vegetable symbiosis technology, fish and vegetable symbiosis can produce many types of systems by combining different modes of hydroponic and aquaculture techniques. The symbiosis of fish and vegetables allows a harmonious ecological balance between animals, plants and microorganisms. It is a low-carbon production model with zero circulation in the future, and it is the most effective way to effectively solve the agricultural ecological crisis.
Fish and vegetable symbiotic farming system model:
1. Blocking cycle mode: After the water discharged from the culture pond is treated by the microbial bed microorganisms, it enters the vegetable cultivation system in a circular manner. After being filtered by the biological absorption of the vegetable roots, the treated wastewater is returned to the culture pond, and the water is cultured. A closed circuit is formed between the pool, the filtrate bed and the planting tank.
2. Open-loop mode: no closed-circuit circulation is formed between the culture pond and the planting tank (or bed), and the wastewater discharged from the culture pond is directly supplied to the vegetable planting system as a one-time irrigation water without returning to the return flow, each time only to the culture pond Add new water. This mode can be used where there is sufficient water.
