What preparatory work should be done before sowing cotton?

I. Do a good job of pre-sowing preparation. Land preparation: for directly sown cotton fields, timely harrowing and smoothing should be done during the suitable moisture period to preserve soil moisture, so that the topsoil is loose and the subsoil is firm.

1. Deep plowing and land preparation: the plowing time for cotton fields can be divided into winter plowing and spring plowing, and winter plowing is better than spring plowing. Winter plowing should be deeper, generally 20-30 cm. Spring plowing should be appropriately shallower, generally 13-16 cm is suitable; after plowing, the land should be finely prepared, so that the topsoil is loose and the subsoil is firm, the soil is loose, and water is stored and moisture is preserved.

2. Apply sufficient base fertilizer: applying sufficient base fertilizer and building up soil fertility is the foundation for high cotton yields. The amount of base fertilizer applied should be determined according to yield, soil fertility, fertilizer quality, and so on. Generally, for cotton fields with a lint yield of more than 125 kg per mu, apply 5000 kg of organic fertilizer, 50 kg of cake fertilizer, 20-30 kg of ammonium bicarbonate, and about 50 kg of superphosphate per mu.

3. Water sufficiently for bottom moisture: according to the winter and spring climate characteristics of our city, watering sufficiently for bottom moisture and creating good surface moisture are effective measures to ensure timely cotton sowing, full emergence in one sowing, and early growth of strong seedlings. For cotton field irrigation, winter irrigation has a good effect; spring irrigation can generally begin after the soil has just thawed, and at the latest should be completed half a month before sowing. This helps the ground temperature rise and ensures timely sowing and full, strong seedlings.

4. Preparation of plastic film and chemicals: generally 2-2.5 kg of plastic film is used per mu. For single-row sowing, plastic film 60 cm wide can be selected; for double-row sowing, plastic film 90 or 100 cm wide can be selected. For pre-emergence herbicide, acetochlor can be sprayed at 100 ml per mu before sowing.

II. Seed preparation: the sowing quality of cottonseed is extremely closely related to sowing and seedling preservation. At present, China is vigorously promoting foam acid delinting, fine selection, and seed coating technology for improved cotton varieties. This is an important measure to improve seed sowing quality, prevent seedling-stage diseases and insect pests, and achieve full emergence in one sowing and early growth of strong seedlings. When buying seeds, be sure to choose seeds produced by legitimate manufacturers with high quality and a good reputation. Generally, the sowing rate for machine sowing is about 1.5-2 kg/mu; the sowing rate for manual dibbling is about 1-1.5 kg/mu.

Determination of sowing date: insect-resistant cotton is generally sown 3-4 days later than conventional cotton, so as to avoid the adverse effects of low temperature as much as possible, and it is required that the 5 cm ground temperature stably pass 14 degrees C (or the air temperature stably remain above 16 degrees C). Note that sowing too early will, due to factors such as low temperature, low temperature and high humidity when encountering rain, and late frost, lead to a major outbreak of seedling-stage diseases and relatively severe seedling death. This point must be given attention. The suitable sowing period for plastic-film cotton is April 15-25; open-field cotton is generally sown after April 25 and finished around May 1. In addition, because cottonseed has difficulty absorbing water in saline-alkali cotton fields, bottom moisture and surface moisture should be ensured, and sowing should be appropriately delayed (requiring the 5 cm ground temperature to stably remain at 16-17 degrees C).