Many cotton farmers do not pay attention to winter management in cotton fields and are accustomed to spring plowing and spring irrigation before spring sowing. In fact, "whole well-worn winter, good cotton in the coming year; winter, good irrigation, no difficulty in planting cotton; winter farming and winter irrigation, high yield of insects and less cotton" has become an important experience in cotton production. To this end, in the winter, farmers should do the following:
The winter ploughing of cotton fields deep plowing in winter can not only turn some of the raw soil out, so that surface weeds and crop residues are buried underground. The loose soil can also improve the ability to store rain and snow, after full winter and spring weathering, The soil matures into a deep and loose layer of living soil, creating good environmental conditions for cotton root development and microbial activity. At the same time, winter is the weakest period for cotton bollworms to survive, and winter plowing can worsen the places where pests depend on wintering. It was observed that adults could not emerge from the soil within 10 cm of the soil. Winter plowing depth is generally about 20 cm. In this way, winter plowing can turn most insects into deeper layers of soil, so that they can not emerge for the second year. Winter plough can also turn some insects out of the ground and freeze or be eaten by natural enemies.
Before the winter plowing, the plowing should be done once before the winter plowing. After the plowing, the larger pupae will be removed. This will not only save water, but also paralyze part of the overwintering insects. The bollworm larvae live in the soil for winter. The depth in the ground does not exceed 10 cm, and the top layer is more than 6 cm. According to the survey, winter pupa in cotton fields can kill about 80% of cotton bollworms.
Fertilization Winter fertilization can be carried out at the same time as winter plowing. In general, the high-quality farmyard manure is 3 to 4 cubic meters, pure nitrogen is 8 to 10 kilograms, and phosphorus pentoxide is 7 to 8 kilograms to promote organic matter decomposition and ripening.
Winter irrigation and winter irrigation followed by winter irrigation can not only solve the contradiction between grain, cotton, and water in the coming spring, but also increase the mortality rate of overwintering alfalfa. At the same time, the fertilizer nutrient applied can be infiltrated into the depth of the soil with the water, and it can be adapted to the cotton root distribution level to achieve optimal nutrient distribution, which is beneficial to the purpose of absorbing cotton plants. Winter irrigation should be uniform, full, transparent principle, the amount of water is not easy to be too large, the time to freeze the day and night is appropriate. After thawing in early spring, it is necessary to loosen the soil in time to increase the ground temperature and maintain soil moisture and ensure the quality of soil preparation.
Studies have shown that when the relative soil moisture content is 40%, the cotton bollworm deuteration rate is 40%; when the soil moisture content is 70%, the bollworm mortality rate is 46.7%, the adult emergence rate is 33.3%; when the soil moisture content reaches In the saturated state, the mortality rate of cockroaches is 100%. According to another data, the wintering mortality rate of cotton bollworms is about 80% for plots cultivated on winter plowing and winter irrigation, and the wintering mortality rate is 60 to 70% for plowed plots and 30 to 40 plots for non-irrigated plots. %. Therefore, a good grasp of prevention and control during the wintering period and reduction in the overwintering base number can have a multiplier effect on controlling the occurrence of the second year of the cotton bollworm.
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