Cultivation method:
In soilless culture, artificially prepared culture solution is used to meet the needs of plant mineral nutrition. In order to make the plant erect, quartz sand, vermiculite, peat, sawdust and plastic can be used as supporting media, and the root system should be ventilated. Years of practice have proved that the yield of soybean, soybean, kidney bean, pea, wheat, rice, oat, beet, potato, cabbage, lettuce, tomato and cucumber is higher than that of soil culture.
Because the demand of plants for nutrients varies with species and growth stages, the formula should be changed accordingly. For example, leafy vegetables need more nitrogen (N) to promote the growth of leaves; Tomatoes and cucumbers need more phosphorus, potassium and calcium than leafy vegetables, but less nitrogen than leafy vegetables. Plants need different nutrients at different growth and development stages. The elements such as nitrogen, phosphorus and potassium in tomato culture solution at seedling stage can be less; When you grow up, you must increase its supply. In summer, with long sunshine, high light intensity and high temperature, tomatoes need more N than in autumn and early winter. Tomatoes growing in autumn and early winter need more potassium to improve their quality.
In order to cultivate the same plant, the formula of culture solution should be constantly modified throughout its life cycle. The culture solution used in soilless culture can be recycled. After plants selectively absorb ions, the concentration of some ions decreases faster than others, and the proportion and pH value of each element change, which gradually becomes unsuitable for plant growth. So every once in a while, NaOH or HCI should be used to adjust the pH value of the culture solution and add more elements with reduced concentration. Since the pH value and the concentration of some ions can be continuously determined by selective electrodes, the amount of acid, alkali or auxiliary elements added can be automatically controlled.
But this recycling can't last indefinitely. When cultivating with solid inert culture medium and culture solution, nutrient solution should also be discharged regularly, or culture solution should be added dropwise to supply enough oxygen to plant roots. When the transpiration of plants is strong, the concentration of culture solution increases and some water needs to be added. The key to the success of soilless culture is to manage the used culture solution to meet the needs of the best nutritional state.
The composition of nutrient solution for soilless culture is easy to control. Moreover, it can be adjusted at any time. As long as there is a certain supply of fresh water, it can be carried out in places with suitable light and temperature and no soil, such as deserts, beaches and desert islands. Soilless culture can also be used to grow vegetables and flowers in suburbs and families of metropolises.