What are the methods for applying fertilizer based on seedling condition during the wheat green-up stage?

Spring has come, the earth's warmth rises, wheat awakens from its winter dormancy, and the green in the wheat fields increases. At this time, many farmer friends ask: Does my wheat need fertilizer? What kind of fertilizer is good? How much fertilizer is appropriate?  And my answer is: apply fertilizer based on seedling condition.

From the physiological perspective of wheat, the stage from green-up to stem elongation is when wheat plants continue tillering, producing leaves, and developing roots, and begin young ear differentiation. It is the most favorable period for consolidating strong seedlings from before winter, helping weak seedlings turn strong, and inhibiting the growth of excessively vigorous seedlings. Therefore, according to different types of wheat fields, adopting different fertilization measures is very necessary. Fertilizing based on seedling condition can be summarized in three words: maintain, promote, and control.

Maintain

For first-class wheat fields that reached "six leaves and one heart" before winter overwintering, have four to five tillers, have a total stem count per mu of about 800,000, with robust plants, normal leaf color, and no yellowing, do not fertilize or water immediately after green-up, to prevent excessive growth and consumption of too many nutrients, which is unfavorable for high yield later. For this type of wheat field, measures such as hoeing, weeding, and pest and disease control should be taken to ensure effective tillering from before winter and safe growth, which is conducive to increasing the wheat ear-setting rate and laying a good foundation for high wheat yield later. This type of wheat field should focus on "maintaining." Wait until around the jointing stage of wheat before fertilizing and watering; this is called the nitrogen postponed application method, which is beneficial for high wheat yield.

Promote

For wheat fields planted too late before winter, with poor fertility conditions and insufficient base fertilizer; wheat seedlings that were short and had few tillers during overwintering; third-class wheat fields where plants are weak, leaves turn yellow, and the total stem count per mu is below 400,000 at green-up; or fields where straw was returned to the field without watering for overwintering, the soil is loose and breathable, water evaporates strongly, the soil is dry, and wheat seedlings show the "hanging root" phenomenon. In similar situations to the above, timely water for green-up and fertilizer for green-up should be applied.

For this type of wheat seedling, choosing the right fertilizer is very important! First, do not apply or apply less organic fertilizer. As the saying goes: barnyard manure nourishes the soil, chemical fertilizer urges the seedlings. Because early spring temperatures are low, farmyard manure decomposes slowly and cannot meet the wheat's nutrient needs. Second, quick-acting chemical fertilizer should be applied; it has a fast fertilizer effect and can promptly supply the needs of wheat growth and development. Urea can be applied at 10-15 kg per mu, and green-up water should be watered well. On this basis, spray Luhong Huisheng Lu foliar fertilizer (30 ml/bag) once, which can promote new root development, resist cold, resist drought, and resist disease, and is beneficial for weak wheat seedlings turning into strong seedlings. Third, when fertilizing, attention should also be paid to weak seedlings in some high-yield fields; apply a little extra fertilizer to them so that their growth becomes uniform, which is beneficial for increasing wheat yield.

Control

For wheat sown too early before winter with too large a seeding rate, resulting in excessive growth before winter, because the rows close too early, leaves spread out, and leaves are too large and too thin, after green-up, measures focusing on "control" should be adopted for them: hoe more, water as little as possible, and restrain the seedlings. Also closely watch whether there is freeze damage; if there is freeze damage, corresponding measures should be taken.

As the saying goes: "Wheat does not flourish twice." If the wheat seedlings are very vigorous, regulation is needed by compaction, deep hoeing, or chemical control techniques before jointing. Paclobutrazol at a concentration of 200 PPM or chlormequat at 0.15%-0.3% can be used, with 30-40 kg of water solution per mu for spraying, to control excessive wheat growth and prevent later nutrient deficiency in wheat. For this type of wheat field, fertilization and watering should be mastered at the stem elongation stage.