Key Technical Points for Early Spring Field Management of Late-Sown Wheat
Because last year's sowing period around the "National Day" (October 1) @#@245@#@ encountered heavy rainfall, wheat farmers did not sow until after the Cold Dew solar term, resulting in late wheat; in addition, the rainfall at that time also delayed the growth of wheat sown at the normal time, which also formed late wheat. As a result, more than half of the 1.1 million mu of wheat sown in this city last year was late wheat. The growth characteristics of late wheat differ from those of ordinary wheat, so the early spring management techniques are also different.
Late wheat generally refers to wheat sown after the Cold Dew solar term. Its growth characteristics differ from those of wheat sown at the appropriate time, mainly shown as: small overwintering seedling age; few tillers; few secondary roots; short mesocotyl. The root system building period of late wheat is mainly in the reviving stage. The main reasons for reduced yield of late wheat in production: first, insufficient ears per mu; second, insufficient phosphate fertilizer, resulting in small old seedlings; third, in early spring management, the practice of managing late-sown wheat early is adopted, with early watering, more watering, and more fertilizer. Due to excessive moisture during the reviving stage, it often causes cold soil, hardened soil, and salt return, which is unfavorable for root development, delays wheat growth, leads to late heading, and in the later stage encounters high temperatures forcing premature ripening and low grain weight. Therefore, the early spring management of late wheat mainly focuses on measures to increase soil temperature, preserve moisture and ventilate the soil, and promote early seedling development.
1. Carry out soil loosening and scarifying. Carry out loosening and scarifying after watering or rain to preserve soil moisture. This is the main management measure for water-saving and drought resistance of early spring wheat.
2. Apply chemical fertilizer, especially phosphate fertilizer, while the soil is still frozen. Because the early spring temperature is low, the soil's ability to supply phosphorus is weak, and at the same time, the wheat root system is small and its ability to absorb phosphorus is also weak, so late wheat is relatively sensitive to phosphorus in early spring. If phosphate fertilizer is insufficient, it is easy to form small old seedlings, causing reduced yield of late wheat. Generally, for late 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 amount and all of the phosphate fertilizer and potassium fertilizer should be applied as base fertilizer. For wheat fields with insufficient base fertilizer, before the soil thaws completely in early spring, the method of furrow fertilization can be used for topdressing while the soil is still frozen, to make up for 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 wheat can be determined by the standard of new tillers (latent tillers) emerging from the ground, new roots growing to about 1.5 cm, and spike differentiation entering the double ridge stage, generally in the middle of early April, and combined with watering, apply 40% of the total nitrogen fertilizer amount. If soil moisture is insufficient, management can be appropriately carried out earlier according to the growth condition of the wheat seedlings.
4. Prevent lodging and control weeds. Because the seeding rate of late wheat is relatively large and the root system is small in early spring, if management is not good, 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.