Most of the traditional open-field irrigation methods are not suitable for use in solar greenhouses. When the full-border irrigation water volume is too large, the places close to the building facilities, such as side walls, columns, etc., are likely to cause local sinking. The open-field sprinkler irrigation equipment cannot be used in the solar greenhouse due to the uneven local spraying and the large range. Practice has proved that the irrigation methods suitable for solar greenhouses are:
1. Micro spray
The water is sprayed by an authoritative rotating micro-sprinkler, generally covering a radius of about 4m, the system pressure is 50kPa to 150kPa, and the flow rate is below 55L/h. The water can be equipped with chemical fertilizers or pesticides, and the irrigation is even, the covering performance is good, and it also has the effect of cooling in summer, which is especially suitable for greenhouse use.
2. Dark irrigation under the mulch
On the basis of the high border, the ditch is opened in the middle and then covered with mulch, and watering is carried out in a dark ditch under the film. Using this method can reduce the air humidity in the greenhouse, thereby reducing crop diseases and insect pests caused by excessive air humidity, and the effect of increasing production is obvious.
3. Drip Irrigation
The main advantage is that it saves water and can completely avoid water loss and deep leakage loss. Combine watering for fertilization to avoid fertilizer loss and improve fertilizer efficiency. It can be used in a greenhouse in cold seasons to avoid the drop in ground temperature caused by irrigation, and at the same time reduce air humidity and disease. Drip irrigation can strictly control the amount of water, keep the soil moist, and promote the high yield of vegetables. At present, a drip irrigation technology under the film has been rapidly developed, which has the advantages of increasing ground temperature, preventing evaporation and saving water.
4. Infiltration Irrigation
Use buried infiltration irrigation pipes to introduce water into the soil where vegetable roots are distributed, and use capillary action to evenly infiltrate water from bottom to top or around. The method does not destroy the soil aggregate structure, has no compacted layer, has less ground evaporation, saves water, and has high irrigation efficiency. Moreover, the ground air humidity is low, which can effectively control diseases. This method has a high one-time investment, but judging from the current development trend, it has broad application prospects in solar greenhouses.
Choose a reasonable irrigation method according to the crop's water demand
The crops cultivated in the greenhouse are fresh living organisms, and the product itself has a high water content. The water demand of the crop directly affects the yield and quality of the product. For this reason, the first principle of irrigation is to understand the water demand of different crops. The water demand of crops is affected by factors such as the place of production of the crop, the climatic conditions of the place of production, and the water absorption capacity of the crop roots. Generally speaking, from the perspective of the entire production cycle, different crop types have different water requirements.
The crops that do not require much water are mainly melon crops such as melon, watermelon, and pumpkin. This kind of crops rely on the well-developed root system to absorb water and have strong drought resistance. Therefore, the number of watering can be less, and too much watering will affect the quality of the product. This kind of crops is better to use infiltration irrigation. Reasonable infiltration irrigation can reduce air humidity, and irrigation is uniform and water-saving. In addition, there are crops that require less water, such as onions and garlic. Their root system is underdeveloped, but they are drought-resistant and damp-loving, and they need to be watered frequently and in small amounts. Therefore, it is better to use root drip irrigation, and the water saving effect is obvious.
Common crops that require water are nightshades, root vegetables and beans. This kind of crops are more drought-tolerant, and the root system has medium water absorption capacity. Therefore, it is necessary to water large amounts of water in a timely manner, and it is suitable for canal irrigation at regular intervals. Keeping the soil dry and wet is extremely beneficial to the growth of such crops.
Crops that require a lot of water include green leafy vegetables, cucumbers, cabbage, cabbage and so on. These crops generally have weak water absorption capacity, and are not resistant to drought. Therefore, they must be irrigated frequently to keep the soil moist. It is better to use micro-spraying for such crops intensively cultivated in the solar greenhouse, and for such crops with large spacing, a combination of micro-spraying and drip irrigation can be used.
In addition, for the irrigation of different crops in the greenhouse, the relative humidity of the air should also be considered. During the photosynthesis of crops, proper air humidity is required. Generally, the suitable air relative humidity is 60% to 80%. Drought-tolerant crops can be lower, and wet crops can be higher, but too high or too low will cause problems. Affect the normal progress of photosynthesis. When the relative humidity of the air is insufficient, it is easy to cause plant wilt and yellow leaves, and it is also easy to cause virus diseases and insect pests such as red spiders and aphids. Micro-sprinkler irrigation can be used to quickly and effectively increase the relative humidity of the air. When the relative humidity of the air is too high, it is easy to cause cucumber downy mildew, tomato gray mold, leaf mold, etc., so attention should be paid to strengthening the ventilation of the greenhouse.
