When should winter wheat be watered with the green-up water? 3 points to note

September is the golden period for planting winter wheat in China. Many regions have already begun busy land preparation, fertilization, and seed preparation, and it is expected that the peak winter wheat sowing period will arrive in the middle to late part of this month. So after winter wheat has been planted, when is the most suitable time to apply the green-up water? What precautions should be taken?

Generally speaking, applying the green-up water to winter wheat in spring is the most suitable.

Green-up fertilizer and water should be applied in a scientific, reasonable, and appropriate amount. If fertilizer and water are applied too early, it will cause excessive ineffective tillering of wheat in spring and an overly large population, which first wastes nutrients and second creates hidden dangers for later lodging and damage from pests and diseases.

The following 3 issues should be noted when applying green-up water to wheat in spring:

1. The time for applying green-up water should be determined according to soil moisture conditions

For wheat fields where sowing was done early before winter by taking advantage of soil moisture but no winter irrigation was carried out, where cultivated land quality is poor, where field moisture loss is severe, as well as wheat fields with poor individual wheat development, small populations, and severe drought, green-up water should be applied in a timely manner. Green-up water should only be applied when the average daily temperature reaches above 3°C.

For ordinary wheat fields, as long as moisture conditions permit, green-up water should be delayed or not applied, and the green-up water should be postponed until the standing-up or jointing stage; for wheat fields with small populations, poor growth, or excessive growth before winter and weak growth in spring, 10 kg of urea per mu can be applied together with irrigation, and after irrigation, when field moisture conditions are suitable, timely shallow hoeing should be carried out to preserve moisture.

2. The amount of green-up water applied must be strictly controlled

Because temperatures vary greatly between day and night in early spring and cold and warm air currents alternate frequently, it is advisable to apply a small amount of water rather than flood irrigation, so as to prevent freezing damage to wheat if a cold wave occurs and both air temperature and soil temperature are too low.

3. Applying green-up water should also be determined according to seedling conditions

For wheat fields sown at the appropriate time before winter, where insufficient soil fertility has resulted in fewer tillers and an insufficient number of ears (about 500,000 total stems per mu before winter), green-up water can be applied, and together with irrigation, 7.5-10 kg of urea per mu and 5-7.5 kg of potassium sulfate or potassium chloride can be applied to promote tillering of wheat in early spring, strive for as many ears as possible, and lay a good foundation for a high yield; for late-sown wheat and strong seedlings with a total stem count of 700,000-900,000 or overly vigorous seedlings with more than 900,000, when fertilizer and water are sufficient, green-up water is generally not applied, and the main measures are intertillage loosening of the soil, moisture preservation, and temperature increase, so as to reduce spring tillering to the minimum; for wheat fields with excessive growth before winter, because the large growth before winter consumed much fertilizer and water and no winter irrigation was carried out, field moisture conditions are poor, and an early-spring cold spell is likely to cause seedling death, so timely application of green-up water should also be noted.