Good cotton planting next year starts with winter soil preparation

Many cotton farmers do not pay attention to winter management of cotton fields, and are accustomed to spring plowing and spring irrigation before sowing in spring. In fact, "prepare the soil well in winter, and cotton planting will go well next year; irrigate the land well during the winter slack season, and planting cotton will be effortless; winter plowing plus winter irrigation means fewer pests and high cotton yields" has become an important experience in cotton production. For this reason, in winter, cotton farmers should do the following tasks well:

Winter plowing Deep winter plowing of cotton fields can not only turn out part of the raw soil and bury surface weeds and crop residues underground; the loosened soil can also improve its capacity to store rain and snow. After full weathering through winter and spring, the soil matures into a deep and loose active soil layer, creating good environmental conditions for cotton root development and microbial activity. At the same time, winter is the weakest period for cotton bollworm survival, and winter plowing can worsen the places on which the pests rely to overwinter. According to observations, within the soil layer below 10 cm, adults cannot emerge from the soil. The depth of winter plowing is generally about 20 cm. In this way, winter plowing can turn most pupae into the deep soil layer so that they cannot emerge the following year. Winter plowing can also turn some pupae out onto the soil surface to freeze to death or be pecked and eaten by natural enemies.

Winter harrowing Before winter plowing, harrow the land once roughly, and after plowing, harrow again to remove larger clods. This can both store water and preserve soil moisture, and can also harrow some overwintering pupae to death. Cotton bollworm pupae overwinter in the soil, at a depth of no more than 10 cm underground, with the greatest number in the topsoil layer above 6 cm. According to surveys, winter harrowing of cotton fields can kill about 80% of cotton bollworm pupae.

Fertilization Winter fertilization can be carried out at the same time as winter plowing. Generally, apply 3-4 cubic meters of high-quality farmyard manure per mu, 8-10 kg of pure nitrogen, and 7-8 kg of phosphorus pentoxide, to promote the decomposition and maturation of organic matter.

Winter irrigation Winter irrigation immediately after winter plowing can not only resolve the conflict between grain and cotton competing for water in the following spring, but also increase the mortality rate of overwintering pupae. At the same time, it can make the applied fertilizer nutrients infiltrate with the water into the deep soil, matching the distribution layer of cotton roots, achieving optimized nutrient distribution and helping cotton plants absorb them. Winter irrigation should follow the principle of being even, sufficient, and thorough. The water volume should not be too large, and the timing should be when it thaws by day and freezes by night. After thawing in early spring, loosen the soil and harrow the land in time to raise soil temperature and maintain soil moisture, ensuring the quality of soil preparation.

Research shows that when the relative soil water content is 40%, the pupation rate of cotton bollworm is 40%; when the soil water content is 70%, the mortality rate of cotton bollworm pupae is 46.7%, and the adult emergence rate is 33.3%; when the soil water content reaches saturation, the mortality rate of pupae is 100%. Other data show that in plots with winter plowing and winter irrigation, the overwintering mortality rate of cotton bollworm pupae is about 80%; in plots with plowing only and no irrigation, the overwintering mortality rate is 60-70%; and in plots with neither plowing nor irrigation, it is only 30-40%. Therefore, doing a good job of control during the overwintering period and reducing the overwintering base can achieve twice the result with half the effort in controlling the occurrence of cotton bollworm the following year.