Detailed Explanation of Key Points of Cotton Cultivation Technology with Drip Irrigation under Plastic Film

I. Pre-sowing Preparation

1. Variety Selection: According to climate and soil conditions, select varieties with a growth period of about 130 days, resistance to Fusarium and Verticillium wilt; compact plant type, short fruiting branches type I~II, small insertion angle; moderate to small leaves, short petioles, not prone to vegetative branches; strong boll setting, and good fiber quality. Such as 9665, JD~3, Fengmian No. 8, Jiumian No. 2, etc.

2. Deep Application of Base Fertilizer: The amount of chemical fertilizer is 8~12 kg of pure nitrogen, 7~10 kg of phosphorus pentoxide, and 3.5 kg of potassium oxide. When deep plowing to kill stubble, deeply plow in farmyard manure and superphosphate. In spring, during land preparation, mix 20 kg of ammonium nitrate phosphate, 20~23 kg of diammonium phosphate, and 6~10 kg of potassium sulfate and apply deeply as base fertilizer.

3. Chemical Weed Control: Before sowing with plastic film mulching, use 100~150 ml of 48% butralin or 80 g of 50% acetochlor per mu, mix with 2~3 kg of water, blend with 50 kg of fine sand, evenly broadcast into the cotton field, shallow rake into the soil, press and cover with film, then sow.

II. Sowing

1. Prepare Machinery Well: Before sowing, conduct a comprehensive inspection and adjustment of the machinery, install the drip irrigation capillary laying device properly, and ensure it is in safe working condition.

2. Sow at the Right Time: When the 5 cm soil temperature stably passes 10°C, this is the beginning of sowing. In normal years, April 15~20 is the best sowing period, sow 6~8 seeds per hole, sowing depth 2~2.5 cm, covering soil thickness 1 cm.

3. Sowing Method: Adopt the water-saving technology of one film with two pipes. Plant 4 rows of cotton with a 145 cm wide film, planting specification is 30+60+30 cm, row spacing between films is 45 cm, plant spacing is 15 cm, and keep 1.1~1.3 million plants per mu. The laying of drip irrigation tape is carried out together with film laying and sowing. The drip irrigation tape is placed in the narrow row, with the rough side of the drip irrigation tape facing up, that is, the flow channel facing up. Note that after the machine stops, pull out an extra length of drip irrigation tape to prevent the drip irrigation tape from shrinking and becoming shorter.

III. Drip Watering and Fertilization

1. Drip Watering at Seedling Stage: Generally after seedling thinning, begin laying surface branch pipes and auxiliary pipes. Drip watering must begin in early June, each time 18~20 m3/mu, and the drip irrigation cycle is 7~8 days. Use fertilizers that are easily soluble in water for drip application, generally urea and a small amount of potassium dihydrogen phosphate. In June, apply fertilizer twice by drip, each time dripping 3 kg of urea and 100 g of potassium dihydrogen phosphate. Fertilization method: adjust the pressure regulating valve in the middle of the filter so that the pressure difference is 0.1 mpa. Generally begin fertilizing 1 hour after drip watering starts, and end 30 minutes before drip watering stops. Each tank drip application time is 40 minutes to 1 hour. The standard for drip watering is that the planting holes show moist soil, with moisture reaching 30 cm.

2. Flowering and Boll Watering: Starting from mid-July, increase the amount of drip watering and fertilization, each drip watering 23~25 m3/mu, drip irrigation cycle 5~7 days, and at the same time increase the amount of fertilization, each time dripping 4~5 kg of urea and 200 g of potassium dihydrogen phosphate. The standard for drip watering is that everything under the film is moist, with moisture reaching 60 cm. Seen from the ground, generally the outermost row of cotton plants shows moisture, the ground is not flooded, and slightly moist and soft is sufficient. Stop drip application of urea before August 10.

3. Drip Watering at Later Stage: Starting from August, appropriately reduce the amount and frequency of drip watering, each drip watering 20 m3/mu, drip irrigation cycle about 8 days. Stop watering before September 8. At the last drip watering, appropriately increase the drip watering amount according to field conditions to ensure sufficient soil moisture during the boll opening period. The whole growth period has 12~14 drip waterings, the total drip watering amount is 250~280 m3/mu, drip urea 25~27 kg, and potassium dihydrogen phosphate 2 kg.

IV. Chemical Regulation Drip irrigation cotton grows steadily and coordinately, and chemical regulation should be early, light, and frequent.

1. Seedling Stage: Conduct the first regulation at the 2~3 leaf stage, spraying 0.2~0.3 g of mepiquat chloride per mu. After one drip watering, for cotton fields with vigorous growth, spray 0.5~0.6 g of mepiquat chloride per mu.

2. Bud Stage: Spray 1.5~2 g of mepiquat chloride per mu every 7~10 days.

3. Flowering and Boll Stage: Before topping, use 2~3 g of mepiquat chloride per mu. 7~10 days after topping, use 7~8 g of mepiquat chloride per mu for heavy regulation.

V. Pest Control

The main cotton pest in our county is aphids. Aphid control is mainly biological control, using insecticide to coat stems or manual spot treatment. When the occurrence area is relatively large, use 100~200 g/mu of systemic monocrotophos or 80 g/mu of 85% carbofuran powder applied with drip water. After three days of application, the effect can reach over 95%.

VI. Recovery of Residual Film and Drip Irrigation Tape

After cotton harvest, the drip irrigation tape must be recovered. After cutting the stalks, pick up all residual film fragments to prevent soil pollution. Other field management is the same as conventional irrigation.

VII. Precautions for Drip Irrigation

1. Frequently check pipe joints. Joints must be firm. When watering, check the capillary pipe ends; there must be no rotten holes, and there must be no standing water on the ground. When watering, pay attention to observing water pressure and irrigation conditions. If the water pressure is found to suddenly decrease, check whether the pipe tape is ruptured, whether joints have fallen off, etc., and handle them promptly.

2. Irrigation must begin in early June and must stop in early September. The irrigation area should not be too large; the area of each rotation irrigation group should not exceed 30 mu. When watering, open one rotation irrigation group at a time. When one rotation irrigation group is finished, first open the next rotation irrigation group, then close the previous rotation irrigation group. It is strictly forbidden to close first and then open. When the system is running, the pressure gauge reading must be strictly controlled, and the system should be operated at the designed pressure to ensure safe and effective operation of the system. Each farmer should obey unified operation management, must not open valves arbitrarily, and must not poke holes in the pipe tape.