Which solar term is better for winter irrigation of wheat?

Winter irrigation time should be grasped accurately. Generally, before and after light snow and heavy snow (1/late month and1early February), the best period is that the average ground temperature in the 5cm topsoil is 5℃ and the temperature is 3℃, and the topsoil "freezes at night and disappears during the day". Too early, the temperature is on the high side, and the evaporation is large, which can not play the role of heat preservation and moisture retention. On the contrary, it may cause wheat seedlings to grow white because of sufficient water, which will seriously cause jointing before winter and easily cause freezing injury; It's too late, the temperature is low, water is not easy to seep down, water is easy to form, and the surface freezes, so plants are easy to freeze to death after irrigation in winter.

Secondly, winter irrigation depends on seedling conditions and soil moisture.

Generally, the soil is dry before overwintering, so winter irrigation is needed in time. If the soil moisture is good, it can be irrigated slowly or not. However, for weak seedling wheat fields with few leaves, few roots and few tillers, watering can be done earlier; For the growing wheat fields in Miao Zhuang, if the soil moisture is good, winter irrigation can be postponed.