Soilless Culture
I. Types, materials and specifications of packagings
At present, there are many types of containers used for soilless seedling cultivation in the world, which can be summarised into 2 categories: one is the container and the seedling planted into the plantation together, such as honeycomb paper cups, peat containers, etc.; the other is the container removed when the seedling is planted, such as plastic bags made of polystyrene, polyvinyl chloride, nutrient cups, cavity trays, etc. The materials used to make containers are soft plastic, hard plastic, peat, paper pulp, straw, etc., with plastic containers dominating. The containers are cylindrical, conical, square and hexagonal in shape, and the most commonly used are plastic bags. Container specifications are determined by the size of the seedling species and the seedlings being cultivated.
II. Preparation of nutrient soil for soilless cultivation
Soilless soil should have the following conditions: it has the necessary nutrients for growth; it has a certain degree of aeration, clay is not suitable; it has a certain degree of stickiness, sandy soil is not suitable, otherwise the soil in the container is easy to disperse when transplanting, losing the role of container seedlings. You can also buy finished soilless substrates such as coconut clay, perlite, vermiculite, peat and so on, like sawdust, mushroom slag, slag after processing can also be used, according to a certain ratio (coconut clay: perlite = 3; 1) will be mixed with substrate materials, the nutrient soil to a certain state of wetness, the degree of wetness to be installed as a container does not leak from the drainage holes of the container, hold into a ball after not deformed as appropriate.
III. Soilless seedlings
1. Filling nutrient soil
Before sowing the seeds, put the soilless soil into a container, either by hand or mechanically. Do not overfill the soil by hand, but fill it to 95% of the capacity of the container, generally about 1 to 2cm lower than the mouth of the container, and compact the substrate slightly to prevent it from collapsing after watering.
2. Sowing
Soilless seedlings in containers must be of good quality and meet the national standard of class 2. Before sowing, the seeds should be soaked, germinated and disinfected in the same way as conventional seedlings. Sow 2-3 seeds per hole for leafy vegetables and 1 seed per hole for melons and fruits, and cover with soil after sowing, the thickness of which depends on the size of the seeds, generally 0.5-1 cm.
3. Watering
When spraying water before seedling emergence, the water flow should not be too fast, so as not to wash out the seeds; water immediately after sowing, and water thoroughly; for tiny seeds, water enough water before sowing and mulching, it is best to use a small amount of water from a fine spout pot to moisten the seeds, so as not to wash out the seeds; water several times and in the right amount during the emergence and seedling period to keep the substrate moist; water more and less during the rapid growth period, so that the substrate alternates between wet and dry; late growth Watering should be controlled during the later stages of growth; stop watering before planting. The first watering must be sufficient and the substrate should be wet.
4. Control temperature and humidity
Too high temperatures can cause seedling burns, too low temperatures can lead to poor growth and unsuitable humidity can cause root mould, rot or withering and death due to lack of oxygen. The appropriate temperature for the growth of seedlings is 18-28°C and the relative humidity is about 80%.
5. Fertilisation
When the seeds have germinated and most of the seed shells have fallen off, fertilisation is started. Fertilisers containing a certain proportion of nitrogen, phosphorus and potassium nutrients are mixed and prepared as an aqueous solution for spraying, dry application of chemical fertilisers is strictly forbidden, and the foliage of seedlings should be washed with water in time after fertilisation. The concentration of nitrogen fertiliser applied outside the roots is 0.1% to 0.2%, or a nutrient solution can be applied by drenching, depending on the time and type of seedling. For example, the soilless nutrient solution used for leafy vegetables has an EC value of 600 in the early stages, 1200 after 7-10 days and about 1200 for melons throughout the seedling period.
6. Interplanting and replenishing seedlings
In container soilless culture, seedlings are often over-dense or unevenly sown because of large seeds or uneven seeding, and must be interspersed and replenished in time. Generally, 7-10 days after the seedlings emerge, the seedlings send out 2-4 leaves to time the seedlings and replenish them. Keep 1 to 3 healthy seedlings in each container and remove the rest. Before transplanting and replanting, water the seedlings and wait for the water to dry out before transplanting them.
7. Transplanting seedlings
When the seedlings have grown to the required size, they can be transplanted.
1. Strong crop growth, high product and good quality
The combination of soilless cultivation and horticulture can reasonably regulate the environmental conditions of light, temperature, water, air and fertiliser for crop growth and give full play to the production potential of the crop. For example, 40 days after sowing yellow light, the plant height, number of leaves and relative maximum leaf area of soilless cultivation are two to four times higher than those of soil cultivation; crop yield can be increased exponentially.
2. Save water, fertiliser, energy and labour
Soilless cultivation can avoid the loss and leakage of soil irrigation water and nutrients as well as the absorption and fixation of soil microorganisms, which are fully absorbed and utilised by crops and improve the efficiency of utilisation.
3. Fewer pests and diseases and avoidance of soil succession problems
Soilless cultivation and horticultural facilities want to combine, in relatively closed environmental conditions, to a certain extent to avoid the outside world and soil pathogens and pests on the crop, plus the crop growth is robust, so the occurrence of pests and diseases is slight, and easier to control. There is no contamination of the soil with parasitic eggs of the planted species and with heavy metals, chemically harmful substances and other public hazards.
4. Great expansion of agricultural production space
Soilless cultivation frees crop production from the constraints of soil and can greatly expand the space available for homeowner production. Soilless cultivation can be used for crop production on vacant hills, wastelands, river beaches, islands, and even beaches and gobi beaches. Especially in densely populated cities, crops can be cultivated using space such as roof terraces and balconies, while improving the living environment.
5. Modernisation of agricultural production
Soilless cultivation, through the integration of multiple disciplines and technologies and the use of modern instruments, meters and operating machinery, can produce crops according to human will, and is a kind of modern agricultural production with a controlled environment. It facilitates the mechanisation and automation of agriculture, thus gradually moving towards industrialisation and modernisation. The many "plant factories" around the world are a sign of modern agriculture. The introduction and construction of modern greenhouses and the accompanying soilless cultivation technology in China in the last ten years have favourably contributed to the modernisation of our agriculture.
Greenhouse cover materials
