Three Soilless Cultivation Methods and Their Pros and Cons: Hydroponics, Aeroponics and Substrate Culture
AbstractThere are three soilless cultivation methods: hydroponics, aeroponics and substrate culture. Hydroponics: the plant roots are placed in direct contact with the nutrient solution, without any substrate. Aeroponics: the nutrient solution is compressed into a mist and sprayed directly onto the crop roots; this method is too expensive and has not yet been promoted and applied. Substrate culture: the crop roots are fixed in an organic or inorganic substrate, and nutrients are supplied to the crops by drip irrigation; this method is simple to operate, low in cost and requires little investment, and it has already been widely used.
1. Hydroponics
Hydroponics is in fact a growing method in which the plants come into direct contact with the nutrient solution and no substrate is needed. The earliest hydroponics involved placing the plants directly into the nutrient solution to let them grow, but this easily led to a lack of oxygen, which affected root respiration and, in severe cases, caused the roots to die. Later, in order to solve this problem, someone in the UK proposed the nutrient film technique of hydroponics.
Principle: a very thin layer of nutrient solution, about 1 cm or so, continuously circulates past the crop roots, which not only ensures the supply of nutrients and water to the crops but also continuously provides fresh oxygen to the roots. This irrigation technique is greatly simplified, and because the roots are isolated from the soil, various soil-borne diseases and pests can be avoided, and there is no need to disinfect the soil.
2. Aeroponics
Aeroponics can also be called mist culture or aeroponic culture. It involves compressing the nutrient solution into a mist and then spraying it directly onto the crop roots, with the roots suspended in the space inside the container. However, the equipment cost of this method is too high, and it also consumes a great deal of electrical energy, and it cannot be without power; this method is only suitable for scientific research applications and cannot be used in large-scale production.
1. Generally, polypropylene foam plastic boards are used; holes are drilled at a certain spacing, and the plants are planted in the holes.
2. Two foam boards are leaned together diagonally to form a triangle, providing space so that the liquid pipes pass through the middle of the triangle and spray directly onto the roots hanging down.
3. Spraying lasts a few seconds about every 3 minutes or so, so that the nutrient solution can be recycled and the oxygen needed by the crop roots can also be ensured.
3. Substrate culture
Among soilless cultivation methods, substrate culture is the one with the largest area of promotion. Its principle is to fix the crop roots in an organic or inorganic substrate and then supply the nutrients needed by the crops by means of trickle irrigation or drip irrigation.
The growing substrate can be put into plastic bags or spread in growing furrows or growing troughs. The nutrient solution in substrate culture is not recycled, so it is also called an open system, and it can also avoid the spread of disease.
Substrate culture has a relatively strong buffering capacity and no conflict among water, oxygen supply and nutrients, and its equipment is simpler than that of hydroponics or aeroponics and requires no power at all. It is low in cost and requires little investment, and it is now already widely used in production. This is a very practical soilless cultivation method.