Strawberry plants need about 16 elements, among which carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur and iron are medium elements, while manganese, boron, copper, zinc, molybdenum and chlorine are trace elements. Plants absorb these elements in appropriate concentrations and proportions at different growth and development stages. The growth and development of plants depends not only on the photosynthesis and respiration of leaves, but also on the absorption of water and nutrients by roots. Water, fertilizer, air, heat and environment around the root system directly affect the absorption of nutrients and water. In order to satisfy the root system's full absorption and balance of different elements in different periods, it is necessary to create the best growth environment for it, such as ventilation, water conservation, ion concentration and proportion, temperature and so on. Soilless culture refers to a cultivation method that uses substrates containing various nutrients (including water substrates) to create the best environment for different growth stages of plants without soil, so as to obtain high yield and high quality. Soilless culture has the following characteristics.
(1) saves labor, is easy to manage, and is convenient to realize the industrialized production of agriculture. Soilless culture does not need soil preparation, weeding and other operations, and water and fertilizer are synchronized. If it is fully automatic, it will be more labor-saving and convenient. Soilless culture is produced in a relatively controllable environment, which greatly reduces the influence of natural environment on strawberry growth and development, and is conducive to the mechanization, automation and industrialization of strawberry production.
(2) High yield, good quality and remarkable economic benefits. Generally speaking, the yield of soilless culture is 3-9 times higher than that of soil tillage culture. For example, the yield of soilless strawberry in China is 25,000-7,000 kg per 667 square meters, and that in Japan is 6,500 kg. Other crops such as bean sprouts can reach 3500 kg, potatoes can reach 1 1000 kg, and cucumbers can reach 2 12 10 kg. Through soilless culture, crops can avoid pests and diseases in the soil, and the produced fruits have good appearance, good quality and high economic benefits.
(3) Save land, water and fertilizer. The results of Italian hydroponics experiment showed that the water requirement per kilogram of hydroponic eggplant was 46 liters, while that of soil-cultured eggplant was about 400 liters, which was 8.7 times that of hydroponic eggplant. The test results of soilless culture in sunlight greenhouse in Yuhong District of Shenyang City show that soilless culture saves 90 liters of water per square meter than soil culture. The experimental results in Japan show that the fertilizer utilization rate of soilless culture is high, and the strawberry with the same yield is produced. The fertilizer consumption of circulating nutrient solution culture is 1/2 ~ 1/3 of soil culture, which means that it saves 50% ~ 70% of fertilizer compared with soil culture and can prevent fertilizer from eutrophication to the environment. Soilless culture can also use uncultivated land, roofs and balconies to grow crops, which can save land and improve the utilization rate of facilities and land.
(4) Less pests and diseases can reduce the use of pesticides. Because soil is the transmission medium of many diseases and insect pests, diseases and insect pests are prone to occur in soil cultivation. Pesticides must be used to control pests and diseases, and the resistance of pests and diseases to pesticides has increased, which has led to more and more serious soil pests and diseases, so the use of pesticides has gradually increased, which not only destroys the environment, but also affects people's health. Soilless culture does not use soil and can artificially control environmental conditions, which not only reduces the base and source of pests and diseases, but also reduces the use of pesticides, and can meet the requirements of green food. General soilless culture can reduce the use of pesticides by more than 50%.
(5) High one-time investment. In general, soilless culture is carried out in the greenhouse. In addition, special substrate, nutrient solution, cultivation bed (tank), circulating liquid supply equipment, etc. All of them are needed, and there must be a liquid storage tank (tank), a pipeline for circulating nutrient solution, a water pump, a conductivity meter, etc. The construction, purchase and installation of these facilities and equipment all need certain funds.
Therefore, soilless cultivation of crops requires a high one-time investment.
(6) Strict technical requirements. Because soilless culture takes water or special materials with extremely low nutrient buffer as the substrate, the management related to roots and roots has become the key to the success of soilless culture, such as the preparation of nutrient solution, the quantity and frequency of supply, the temperature and air content of nutrient solution, the salt concentration around roots, the temperature, humidity and oxygen content, the humidity, light, temperature and carbon dioxide concentration in facilities, etc. It is necessary to strictly follow the standard operation, otherwise the ideal effect will not be achieved. In production, it is often found that soilless cultivation by soil tillage technology leads to poor plant growth, low yield and poor benefit. Therefore, soilless culture must be operated according to technical specifications in order to achieve the goal of high quality, high yield and high benefit.