Cultivation Techniques for Cotton with Lint Yield Above 150 kg per Unit Area

In the past two years, our regiment has vigorously promoted high-density cultivation and integrated supporting new technologies in cotton production, strengthened the breeding and extension of new varieties, and still achieved a bumper harvest despite natural disasters and pest and disease damage. Even more encouraging, high-yield strips with lint yields of 150-180 kg per unit area have emerged in batches for two consecutive years. In 2003, a disaster-prone year, the area of our regiment's cotton with lint yield above 150 kg reached 2,386 hectares, accounting for 37.7% of the total cotton sown area, and the area with lint yield above 180 kg was about 1,093 hectares, accounting for 17.3% of the total cotton sown area.

I. Strengthen the awareness of fighting disasters for high yields and grasp the initiative

In terms of management measures, this is mainly reflected in six aspects: First, effectively implement routine measures. Irrigate sufficiently to build up subsoil moisture and treat salinity and alkalinity; plow at suitable moisture before sowing and strictly control land preparation quality; manually select seeds, coat seeds, and treat seeds with chemicals, and strictly control sowing quality. Second, further improve the breeding, introduction and extension of cotton varieties. Third, the optimal sowing period for high-yield cotton fields is April 7-15, and the sowing date does not need to be advanced further. Fourth, appropriately increase planting density. Fifth, increase the application of organic fertilizer and apply base fertilizer deeply; under drip irrigation under film, the first drip irrigation should also be delayed to promote deep penetration of the main root, encourage more lateral roots, and enhance drought resistance. Sixth, appropriately advance topping to prevent excessive vegetative growth and late maturity.

II. Yield Structure for Lint Yield Above 150 kg per Unit Area

Except for low-yield fields, sandy soils and marginally suitable cotton areas, on land with medium fertility or above (including medium-grade land), using and promoting current cotton varieties and supporting high-tech cultivation, the yield structure for lint yield above 150 kg per unit area is: 13,500-15,500 harvested plants per 667 sq m, 85,000-90,000 total bolls, 5.5-6.5 bolls per plant, average single boll weight 4.7-5.0 g, lint percentage about 40%, seed cotton yield 400-440 kg, and lint yield 160-170 kg.

III. Focus on Uniformity and Promote Evenness

Uniformity refers to individual cotton plants growing evenly, developing steadily, and having a reasonable plant type. Evenness refers to the cotton plant population in the field being highly consistent in height, with the same leaf color, neither premature senescence nor excessive growth, clean and neat. Uniformity is the condition for evenness, and evenness is the manifestation of uniformity.

For high-yield fields with yield above 150 kg per unit area, the best row and plant spacing configuration is the wide-narrow row strip pattern, appropriately widening the large rows and appropriately narrowing the narrow rows and plant spacing, that is, "wide rows with dense plants," with an average row spacing of 34-42 cm and plant spacing of 10-12.5 cm. For example, (66+10) x 11.5, (50+10) x 12.5, (55+28) x 11.5, etc. With these configurations, the theoretical plant number per 667 sq m is above 15,000-17,000 plants. At the same time, this configuration is conducive to the full use of soil fertility and light energy, tapping the population's yield-increasing potential, and also helps individual cotton plant growth and development, giving play to their self-regulating ability. Early-stage individual development is good, and in the late stage the population is not too dense, with ventilation and light penetration, alleviating the contradiction between individuals and the population.

IV. Scientific Promotion and Control for Steady Growth Throughout

1. Scientific fertilizer and water management

① Fertilization: apply 0.8-1.0 tonnes of farmyard manure or 80-100 kg of oil residue, 45-50 kg of urea, about 15 kg of triple superphosphate, 5-8 kg of potassium sulfate, and 2-3 kg of boron-zinc micronutrient fertilizer and potassium dihydrogen phosphate per 667 sq m. The ratio of nitrogen, phosphorus and potassium in southern Xinjiang is 1:0.3-0.35:0.12-0.14. The fertilization principle is to apply base fertilizer deeply, apply heavy fertilizer at flowering and boll stage, and supplement with a top-covering fertilizer. Under drip irrigation under film, appropriately increase the proportion of topdressing during the growth period.

Base fertilizer: For furrow-irrigated and hose-irrigated cotton fields, all phosphorus fertilizer, 70%-80% of total potassium fertilizer, and 50%-70% of total urea are used as base fertilizer, with the remainder used as topdressing. For drip-irrigated cotton fields, all cake fertilizer, all or 80% of phosphorus fertilizer, about 70% of potassium fertilizer (50%-60% for sandy soils), and 40%-60% of total urea are used as base fertilizer, with the remainder applied with water during the growth period.

Flowering and boll fertilizer: For conventional furrow-irrigated cotton fields, flowering and boll fertilizer is generally applied in two furrow applications, namely at the initial flowering stage and before the full flowering stage, light first and heavy later. At the initial flowering stage, apply 8-10 kg of urea and 2-3 kg of potassium sulfate per 667 sq m; at the full flowering stage, apply 12-15 kg of urea and 3-5 kg of diammonium phosphate per 667 sq m. In the later period, to increase boll number and boll weight and prevent premature senescence, supplement with boll-strengthening fertilizer in combination with the third or fourth irrigation (early August), using soil drip irrigation to apply about 4 kg of urea. For cotton fields with smaller upper leaves, lighter leaf color, and more bolls set in the middle and lower parts, more can be applied appropriately, but not too late or too much. For drip-irrigated cotton fields, during the growth period, depending on soil fertility and texture, apply about 30 kg of urea or cotton-specific fertilizer per 667 sq m in 5-7 drip applications, including one application around initial flowering, one at early flowering, three during full flowering and boll setting, and one to two during peak boll setting. The drip fertilizer amount per 667 sq m is 3-4 kg in the early and late periods and 4-5 kg in the middle period. For sandy soils, the early amount should not be large, and attention should be paid to supplementary drip application later. When drip-applying nitrogen fertilizer in the middle and late periods, combine with a small amount of potassium dihydrogen phosphate, which helps increase boll weight, prevent premature senescence, and reduce shedding.

For cotton fields or sections with weak growth, spray foliar fertilizer 1-2 times at the 7-leaf stage. Spray foliar fertilizer 2-3 times during the full flowering and boll-setting period to supplement nutrients in time, promote early maturity, and prevent premature senescence.

② Irrigation during the growth period: For conventional furrow-irrigated cotton fields, irrigate 4-5 times during the growth period. The first irrigation is key; generally irrigate at flowering, and do not irrigate unless there is drought. The irrigation amount is 60-70 cubic meters per 667 sq m, insisting on fine-flow furrow irrigation, irrigating to 1/3 of the furrow. Sandy soils can be irrigated earlier for the first irrigation, and fertilizer to promote bud formation can be applied according to plant condition. Irrigate the second time at an interval of about 10 days, with an irrigation amount of 80 cubic meters per 667 sq m, to meet the water demand during the flowering and boll stage. Irrigate the third and fourth times about every 15 days; in the later period, cotton fields must not suffer drought. Stop irrigation from mid-to-late August to early September.

For drip-irrigated cotton fields, drip irrigation is applied 9-12 times during the whole growth period, with a drip irrigation amount of 200-250 cubic meters per 667 sq m, following the principle of "less early, more in the middle, less late." From full bud stage to initial flowering, apply 1-2 times at an interval of about 10 days, with 15-20 cubic meters per 667 sq m each time; during the flowering and boll stage, apply 4 times at an interval of 7 days, with 30 cubic meters per 667 sq m each time; in August, apply 3 times, with 20-25 cubic meters per 667 sq m each time; in early-to-mid September, apply 1-2 times, with 15-20 cubic meters per 667 sq m each time, mainly to nourish roots with water, protect leaves with roots, and preserve bolls with leaves.

2. Chemical control according to seedling condition

For vigorously growing cotton fields, at the bud stage, 6-7 leaf stage and 9-10 leaf stage, apply 0.8-1.2 g of mepiquat chloride per 667 sq m, mainly to regulate the growth of middle leaves, internodes and middle and lower fruiting branches, and maintain stable growth during the bud stage. For cotton fields under drip irrigation under film, water and fertilizer regulation should be primary, supplemented by chemical control and film regulation. At the initial flowering stage, chemical control is used to prevent hollowing. From the 12-leaf stage to the 13-leaf stage, the amount of mepiquat chloride is 2.0-2.5 g per 667 sq m, mainly to regulate the growth of upper leaves, internodes and fruiting branches, to prevent hollowing and ensure more bolls set in the middle. For cotton fields under drip irrigation under film, apply light control according to plant condition. During the full flowering and boll-setting period, 8-10 days after topping, when the upper internodes and fruiting branches have elongated to a certain length, carry out heavy control.

3. Early topping and early pruning

Topping is suitable from July 5-15, when plant height is 65-75 cm. Remove side shoots 8-10 days after topping, with flowers as the boundary, and vigorously growing sections can be done appropriately earlier. From late July to early August, cut off ineffective flower buds to help increase boll weight.

V. Integrated Pest and Disease Control Is the Guarantee for Achieving High Yields

Pest control mainly focuses on cotton bollworm, cotton aphid and cotton spider mite. Cotton bollworm control: adhere to agricultural control to reduce the overwintering population base. At the peak of egg laying, apply biological agents or pesticides with low toxicity to natural enemies for control, "strike at the egg peak, control before the third instar," so as to effectively control the population density of each generation. For chemical control, Bt pesticide can be selected. Cotton aphid: based on controlling overwintering aphid sources and early spring aphid sources, focusing on severely controlling central aphid plants and spot-by-spot control, using chemicals scientifically and reasonably, fully utilizing and protecting natural enemies, and centering on controlling pests with beneficial insects to control cotton aphid damage. Cotton spider mite control: based on agricultural control, focusing on controlling mite sources and spot-by-spot selective treatment, protecting and utilizing natural enemies, and controlling spider mite damage. Chemical control should be vigorous, using specialized acaricides; when even a little is found, treat the whole patch chemically, control spider mites at the spot-occurrence stage and before the first irrigation, and strictly prevent spread and expansion. For Fusarium and Verticillium wilt, the most effective control method at present is to plant disease-resistant varieties. Where conditions permit, regiments can implement paddy-upland rotation in strips with severe Fusarium and Verticillium wilt to reduce damage.

VI. Effectively Carry Out Residual Film Recovery and Control Residual Film Pollution in Cotton Fields

In recent years, with the extension of drip irrigation under film, the recovery rate of plastic film has declined considerably. The average residual film amount in cotton fields is 3.5 kg per 667 sq m, with the highest reaching 17.9 kg. When film is removed before the first irrigation in cotton fields, in cotton fields with continuous film-mulched cotton planting for 5-6 years, the average residual plastic film amount is 4 kg per 667 sq m, with an annual average residue of 0.67-0.80 kg. When film is picked up only after cotton harvest or in the following spring, in cotton fields with continuous film-mulched cotton planting for 3-8 years, the residual plastic film amount reaches 6.83-15.07 kg per 667 sq m, with an annual average residue of 2.28-2.55 kg. These residual films are mainly distributed in the 0-15 cm soil layer, generally accounting for 60%-90% of the total residue. Residual film cannot combine with soil colloids, and when it accumulates to a certain amount, it will severely damage soil physical properties. At the same time, it slows the speed of upward and downward soil water movement; affects the quality of plowing, land preparation, sowing, intertillage and fertilization; causes seed rot and reduces emergence rate; affects root penetration and extension, and consequently affects the normal growth and development of the aboveground part of cotton, increasing bud and boll shedding and reducing yield.

At present, conventional furrow-irrigated cotton fields still remove film manually before the first irrigation; drip-irrigated cotton fields under film first remove the film edges before the first drip irrigation, and then remove the entire film in August. Actively demonstrate, test and promote shallow-buried and deep-buried drip irrigation under film, and manually remove film before the wide rows close, in order to reduce the labor intensity of film removal and pollution.