Sunflower Fertilization Techniques: Key Points and Methods Explained
Environmental Requirements. Sunflowers have strong tolerance to low temperatures at both the seedling stage and the mature stage. Seeds begin to swell and sprout at 2°C-4°C, can germinate at 4°C, can emerge at 5°C, and 8°C-10°C is sufficient for normal emergence. Seedlings can withstand several hours at -4°C and can still recover after the low temperature...
1. Base fertilizerType. Mainly organic fertilizer, combined with chemical fertilizer.
Fertilization period and method. Applying base fertilizer in combination with autumn plowing is more conducive to preserving fertilizer than applying it during spring plowing, and can also increase the emergence rate. Fertilization method: in combination with mechanical operations, use broadcast application, rake evenly, and then plow. When using horse-drawn farm implements, apply the fertilizer in the furrows, then close the ridges.
Fertilizer amount. Organic fertilizer 1000-2000 kg per mu; chemical fertilizer: nitrogen 5-8 kg, phosphorus pentoxide (P2O5) 4-5 kg. Potassium fertilizer can be controlled according to the soil potassium content obtained from soil testing. If it reaches the normal standard, potassium fertilizer does not need to be applied; if it does not reach the normal standard, 3-4 kg of potassium sulfate can be applied per mu.
2. Seed fertilizer.
Seed fertilizer should be mainly phosphorus, to achieve the purpose of strengthening seedlings. For example, ammonium bicarbonate or ordinary superphosphate plus a small amount of urea can also be used as seed fertilizer.
Method of using seed fertilizer. In combination with sowing, apply organic fertilizer and chemical fertilizer 2-3 cm below the seeds, or 2-3 cm beside the seeds.
3. Topdressing.
Fertilizer applied after sunflower emergence is called topdressing. Sunflower is a crop with a relatively high fertilizer requirement. Relying only on base fertilizer and seed fertilizer cannot fully satisfy the nutrient needs of sunflowers during budding, flowering, and the later growth period, when vegetative growth and reproductive growth proceed simultaneously. Especially for summer-sown sunflowers, topdressing is even more important when base fertilizer is insufficient or not applied. Topdressing is mainly nitrogen fertilizer, combined with a certain amount of potassium fertilizer. Fertilizer types include ammonium nitrate, urea, ammonium bicarbonate, potassium chloride, and other chemical fertilizers, as well as quick-acting fertilizers such as decomposed human urine and manure and plant ash. In addition, it also includes some trace elements such as zinc, molybdenum, manganese, and copper. The amount and timing of sunflower topdressing are determined mainly based on factors such as the fertilizer requirements at different growth stages, the soil's fertilizer supply capacity, climatic conditions, and the amount of base fertilizer and seed fertilizer applied. At the same time, in production, it is often also combined with field management measures. The period from budding to flowering in sunflowers is precisely the vigorous production stage in which vegetative growth and reproductive growth occur simultaneously, requiring much and concentrated nutrients, so topdressing should be arranged before this period. Generally, nitrogen fertilizer and potassium fertilizer have a better effect when applied at the 7-8 leaf stage. Generally, a small hole is dug 10-15 cm from the base of the sunflower root stem to apply fertilizer, then soil is immediately covered. The fertilization depth depends on the type of topdressing and soil moisture conditions. Fertilizers that volatilize easily, such as ammonium bicarbonate and ammonia water, should be applied deeply. In cases of drought and dry soil, deep application should also be used so that the fertilizer contacts moist soil and can readily take effect in time. If intertillage and early topdressing are used, it can be combined with the first intertillage, with a cultivation depth of 8-10 cm, and it must be about 15 cm away from the seedlings. For late topdressing, it can be combined with the last intertillage, and the fertilizer can be applied between the rows, with the cultivation depth still 8-10 cm. In short, when topdressing, attention should be paid to both depth, applying it into the moist soil layer, while not damaging the plant root system due to deep application, and also making sure the fertilizer is not too close to the plant and burns the roots.
4. Foliar spraying.
Spraying 0.005% zinc, copper, manganese, and molybdenum solution at the sunflower budding stage can increase the oil content of the seeds, reduce the rate of empty and shriveled seeds, and improve seed plumpness. Foliar spraying with 0.1% urea solution has a clear yield-increasing effect. Spraying a 1:3:3 nitrogen, phosphorus, potassium solution at sunflower flowering can greatly increase yield and can also increase oil content.