First, the characteristics of watermelon planting
Spring greenhouse seedlings are generally planted in late January to early February and in mid-to-late March. Autumn greenhouse seedlings are planted in late May to early July, one month later. The density is 680~700 plants/mu, the row spacing is 105~110 cm, and the plant spacing is 70~80 cm. Do 畦: ridge height 18~20 cm, ridge width 40 cm, while laying the drip irrigation tube back cover film sealed. Bottom fertilizer: organic fertilizer 3500~8000 kg / mu, compound fertilizer (15:15:15) 50 kg / mu, potassium sulfate 15 kg / mu, and fully mixed cover soil.
Second, micro-irrigation and fertilization facilities
The micro-irrigation system is generally drip irrigation, and one or two drip irrigation belts (tubes) are laid per raft. The spacing between the drip heads is equivalent to the plant spacing, and the installation and use refer to the relevant specifications. The fertilizing device is generally a differential pressure fertilizing tank or a venturi fertiliser, and the fertilizing tank has a volume of not less than 15 liters.
Third, the common fertilizer selection
1. Fertilizer requirements: soluble in irrigation water at room temperature, less than 5% insoluble matter, small in conditioning agent; no precipitation with other fertilizers; no significant change in pH of irrigation water; corrosiveness of irrigation system small.
2, commonly used fertilizer: water-soluble good solid fertilizer or high concentration of liquid fertilizer, such as urea, potassium dihydrogen phosphate, potassium nitrate, ammonium nitrate, potassium chloride, etc., or water-soluble special compound fertilizer (special formula fertilizer), recommended Use a special formula fertilizer.
Fourth, micro-irrigation and fertilization program
1. Micro-irrigation scheme: watering should be poured once in time after planting. Generally, drip irrigation should be more than 8 hours, and can also be used for furrow irrigation. After emergence, depending on the situation, drip irrigation can be adopted. The watermelon in the protected area is usually dripped once every 5~7 days in seedling stage, each time 10~12 squares/mu, and the dring period is drip every 5~7 days, each time 12~14 squares/ Mu, in the expansion period, every 6~8 days, drip irrigation once, each time 13~16 square meters/mu. Open field watermelons are usually dripped once every 5~7 days in seedling stage, each time 10~15 squares/mu, drip irrigation every 5~7 days, each time 13~16 squares/mu, and every 6~8 days of drip irrigation in the expansion period Once, each time 15~18 square meters/mu.
2, fertilizer program: the general principle is to add fertilizer once every two times. Protected watermelons are usually topdressed every 8~10 days in seedling stage, each time adding 10~12 kg/mu of fertilizer, the ratio of fertilizer (N:P2O5:K2O) is 20:15:15; every 8~10 days of stretching period Topdressing once, each time 12~14 kg/mu, fertilizer ratio is 20:5:20; every 10~12 days in the expansion period, once every 15~18 kg/mu, the fertilizer ratio is 20:5:25 . Open field watermelons are usually topdressed every 8~10 days in seedling stage, each time adding fertilizer 10~12 kg/mu, the fertilizer ratio is 20:10:15; every 8~10 days in the extension period, topdressing once every time, 12~14 Kg/mu, the fertilizer ratio is 20:5:20; every 10~12 days in the expansion period, the topdressing is 15~18 kg/mu, and the fertilizer ratio is 20:0:20.
Five, micro-irrigation operation
1. Irrigation operation
When irrigation, the valve on the fertiliser tank should be closed, and the control valve of the drip irrigation system branch pipe should be completely opened and irrigated according to the micro irrigation scheme. Turn off the power at the end of the irrigation and immediately close the control valve. The drip irrigation depth is generally 30 cm. The principle of drip irrigation is a small number of times, do not extend the drip irrigation time to achieve the purpose of multi-irrigation.
2, fertilization operation
(1) Fertilizer preparation
According to the requirements of the fertilizer application, the fertilizer is first dissolved in water, and the fertilizer can be dissolved in water one day before fertilization. When fertilizing, filter the yarn (net) and pour the fertilizer into the differential pressure fertilization tank, or pour it into an open container and inhale it with a venturi fertiliser.
(2) Fertilization operation
Differential pressure fertilization method: The fertilization tank is connected in parallel with the pressure regulating valve on the main pipe, and the inlet pipe of the fertilizing tank should reach the bottom of the tank. Before fertilizing, water is poured for 20~30 minutes. When fertilizing, tighten the can lid and open the inlet valve of the tank. After filling the tank with water, open the outlet valve of the tank to adjust the pressure difference to keep the fertilization speed normal. Fertilization time is generally controlled at 40 to 60 minutes to prevent uneven or insufficient fertilization.
Venturi fertilization method: the venturi device is connected in parallel with the valve on the main pipe. After filtering the pre-dissolved fertilizer liquid, it is poured into an open container, and the tip of the venturi is placed in the fertilizer liquid. There is a filter and the tip should not be placed at the bottom of the container. Open the valve on the suction pipe and adjust the valve on the main pipe to make the suction pipe absorb the fertilizer evenly and stably.
Note: Every time you add fertilizer, you must control the concentration of fertilizer. Generally, add 1 kg of fertilizer in 1 square water. The amount of fertilizer should not be too large to prevent waste of fertilizer and system blockage. After each fertilization, it will be irrigated for 20~30 minutes. To flush the pipe.
3, system maintenance
Each time the micro-irrigation system is operated, the sewage valve at the lower part of the filter should be drained, and the residue at the bottom of the fertiliser tank should be cleaned frequently. In some areas, water has a high carbonate content. After each irrigation season, 30% dilute hydrochloric acid solution (40-50 liters) is used to inject the drip irrigation tube for 20 minutes, then rinse with water.
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