Fertilization Technology of Micro-irrigation for Watermelon

Micro-irrigation fertilization is a kind of water-saving, fertilizer-saving and efficient agricultural production technology that injects fertilizer solution into micro-irrigation system under the condition of pressurized water source and transports fertilizer solution to crop root zone soil uniformly and stably with small flow.

I. planting characteristics of watermelon

Spring greenhouse seedlings are generally planted from late January to early February and mid-late March, while autumn greenhouse seedlings are planted from late May to early July and a month later. The density is 680cm / mu, the row spacing is 105cm / mu, the plant spacing is 70cm / mu. Make the border: the ridge is 1820 cm high and 40 cm wide. At the same time, the drip irrigation pipe is laid and the plastic film is sealed. Apply base fertilizer: organic fertilizer 3500-8000kg / mu, compound fertilizer (15:15:15) 50kg / mu, potassium sulfate 15kg / mu, and fully mix the soil.

2. Micro-irrigation and fertilization facilities

Micro-irrigation system is generally drip irrigation, one or two drip irrigation belts (pipes) are laid in each bed, and the distance between drip heads is equal to that between plants. The fertilization device is generally a pressure differential fertilizer tank or a Venturi fertilizer applicator with a volume of not less than 15 liters.

III. Selection of commonly used fertilizers

1, fertilizer requirements: at room temperature can dissolve in irrigation water, insoluble matter less than 5%, conditioning agent content is small; mixed with other fertilizers basically does not produce precipitation; will not cause drastic changes in irrigation water pH; less corrosive to the irrigation system.

2. Commonly used fertilizers: solid fertilizer with good water solubility or liquid fertilizer with high concentration, such as urea, potassium dihydrogen phosphate, potassium nitrate, ammonium nitrate, potassium chloride, etc., or water-soluble special compound fertilizer (special formula fertilizer) is recommended.

IV. micro-irrigation and fertilization scheme

1. Micro-irrigation scheme: after planting, drip irrigation should be more than 8 hours, and furrow irrigation can also be used. Drip irrigation can be used after emergence depending on soil moisture. Watermelons in protected areas are generally drip irrigated every 5-7 days, 10-12 square meters / mu every 5-7 days, 12-14 square meters / mu every 5-7 days, and 13 square meters / mu every 6-8 days during the expansion period. Watermelon in open field is drip irrigated once every 5-7 days, 10-15 square meters / mu every 5-7 days, 13-16 square meters / mu every 5-7 days, and 15 square meters / mu every 6-8 days during the expansion period.

2. Fertilization scheme: the general principle is to add fertilizer every two drip irrigation. Watermelons in the protected field are generally topdressing every 8-10 days, with a fertilizer ratio of 10-12 kg / mu and a fertilizer ratio (N:P2O5:K2O) of 20-15-15; in the tending stage, topdressing of watermelons is 12-14 kg / mu every 8-10 days, with a fertilizer ratio of 20520; during the expansion period, topdressing is applied once every 10-12 days, with a fertilizer ratio of 15 kg / mu, and the fertilizer ratio is 20:5:25. Watermelons in the open field are generally topdressing every 8 to 10 days, with a fertilizer ratio of 10 to 12 kg / mu, with a fertilizer ratio of 20 to 10; during the tending period, topdressing is applied every 8 to 10 days, with a fertilizer ratio of 12 to 14 kg / mu, with a fertilizer ratio of 20 to 5; during the expansion period, topdressing is applied every 10 to 12 days, with a fertilizer ratio of 15 to 18 kg / mu, with a fertilizer ratio of 20:0:20.

5. Operation of micro-irrigation and fertilization

1. When operating irrigation, the valve on the fertilizer tank (device) should be closed, the control valve of the branch pipe of the drip irrigation system should be fully opened, and the irrigation should be carried out in accordance with the micro-irrigation scheme. Cut off the power at the end of irrigation, and then close the control valve immediately. The wetting depth of drip irrigation is generally 30 cm. The principle of drip irrigation is a small number of times, do not prolong the time of drip irrigation to achieve the purpose of more irrigation.

2. Fertilization operation

(1) Fertilizer preparation in accordance with the requirements of the fertilization scheme, the fertilizer can be dissolved in water first, or in water the day before fertilization. When fertilizing, filter with gauze (net), pour the fertilizer liquid into the pressure differential fertilizer tank, or pour it into an open container and inhale it with a Venturi fertiliser.

(2) fertilization operation pressure differential fertilization method: the fertilizer application tank is in parallel with the pressure regulating valve on the main pipe, and the inlet pipe of the fertilizer tank should reach the bottom of the tank. First irrigate for 20-30 minutes before fertilizing. When applying fertilizer, tighten the lid of the tank, open the intake valve of the tank, and then open the outlet valve of the tank after filling the tank with water. Adjust the pressure difference to keep the fertilization speed normal. The fattening time is generally controlled at 40-60 minutes to prevent uneven or insufficient fertilization. Venturi fertilization method: the Venturi device is connected in parallel with the valve on the main pipe, the pre-dissolved fertilizer liquid is filtered and poured into an open container, and the suction head of the Venturi device is put into the fertilizer liquid. The suction head should be filtered, and the suction head should not be placed at the bottom of the container. Open the valve on the straw and adjust the valve on the main pipe so that the straw can absorb the fat evenly and stably.

Note: every time you add fertilizer, you must control the concentration of fertilizer solution, generally add 1 kg fertilizer to one square of water, the amount of fertilizer should not be too large, prevent waste of fertilizer and blockage of the system; irrigate for 20 minutes for 30 minutes after each fertilization to flush the pipe.

3. Maintenance of the system

Every time the micro-irrigation fertilization system runs, the discharge valve in the lower part of the filter should be opened to discharge pollution, and the residue at the bottom of the fertilizer tank should be cleaned frequently. After each irrigation season, 30% dilute hydrochloric acid solution (40-50 liters) is injected into the drip irrigation tube, retained for 20 minutes, and then washed with clean water.