Detailed Explanation of Early Spring Management Techniques for Late-Sown Wheat

Because the sowing period around "National Day" last year @#@245@#@ encountered heavy rainfall, wheat farmers did not sow until after the Cold Dew solar term, forming late-sown wheat; in addition, the rainfall at that time also delayed the growth of wheat sown at the normal time, also forming late-sown wheat. Of the 1.1 million mu of wheat sown in this city last year, more than half was late-sown wheat. The growth characteristics of late-sown wheat differ from ordinary wheat, so early spring management techniques are also different.

Late-sown wheat generally refers to wheat sown after the Cold Dew solar term. Its growth characteristics differ from wheat sown at the appropriate time, mainly shown as: small seedling age before winter; few tillers; few secondary roots; short mesocotyl. The root system construction period of late-sown wheat is mainly in the reviving stage. The main reasons for yield reduction of late-sown wheat in production: first, insufficient ears per mu; second, insufficient phosphate fertilizer, resulting in small old seedlings; third, in early spring management, adopting the practice of early management for late sowing, watering early, watering more, and fertilizing more. Due to excessive moisture during the reviving stage, it often causes cold soil, compacted soil, and salt return, which is unfavorable to root development, delays wheat growth, leads to late heading, and in the later stage encounters high temperature forced ripening with low grain weight. Therefore, early spring management of late-sown wheat mainly revolves around measures to increase soil temperature, preserve moisture and improve aeration, and promote early seedling development.

1. Carry out soil scarification. After watering or rain, carry out scarification to preserve soil moisture. This is the main management measure for water-saving and drought resistance of wheat in early spring.

2. Apply chemical fertilizer, especially phosphate fertilizer, while the soil is still frozen. Because early spring temperatures are low, the soil's ability to supply phosphorus is weak, and at the same time, the wheat root system is small and its phosphorus absorption capacity is also weak, so late-sown wheat is relatively sensitive to phosphorus in early spring. If phosphate fertilizer is insufficient, small old seedlings are easily formed, causing yield reduction of late-sown wheat. Generally, for late-sown wheat with a yield of more than 400 kg per mu, the appropriate amount of nitrogen, phosphorus, and potassium fertilizer throughout the growth period is 35 kg of urea, 25 kg of diammonium phosphate, and 15 kg of potassium sulfate per mu. And 60% of the total nitrogen and all of the phosphate and potassium fertilizers should be applied as base fertilizer. For wheat fields with insufficient base fertilizer, before the soil thaws completely in early spring, the method of trench application can be used for topdressing while the soil is still frozen, to make up the insufficient portion.

3. Delay the time of spring fertilization and watering. For wheat fields with sufficient subsoil moisture and timely winter irrigation before winter, the suitable watering time for late-sown wheat can be determined by the standard of new tillers (dormant tillers) emerging above ground, new roots growing to about 1.5 cm, and spike differentiation entering the double ridge stage, generally in the middle ten days of early April, and combined with watering, apply 40% of the total nitrogen fertilizer. If soil moisture is insufficient, management can be appropriately advanced according to the growth condition of the wheat seedlings.

4. Prevent lodging and control weeds. Because the sowing rate of late-sown wheat is relatively large and the root system is small in early spring, if not managed well, lodging is very likely to occur, so from the standing stage to the jointing stage, attention should be paid to preventing lodging and controlling weeds.