Fertilizer application outside the root system, also known as foliar feeding, is an effective method to supplement nutrients and improve crop growth. First, it's important to choose the right type of fertilizer suitable for foliar use. Fertilizers such as urea, potassium dihydrogen phosphate, potassium nitrate, potassium sulfate, and ammonium sulfate are highly effective when applied externally. Superphosphate and ash leaching solutions, as well as ammonium metaphosphate and most micronutrient fertilizers, can also be used. However, highly volatile fertilizers like ammonia or ammonium bicarbonate, and those containing chloride ions such as ammonium chloride or potassium chloride, should be avoided, as they may lead to significant nutrient loss or even harm the crops.
Second, the amount and concentration of the fertilizer solution should be adjusted based on the type of crop and its growth stage. For example, a typical foliar application might include 1-2% urea, 0.3-0.5% potassium dihydrogen phosphate, 3-5% superphosphate leaching solution, 0.01-0.1% ammonium molybdate, 2-3% ammonium metaphosphate, 0.1-0.2% borax, and 1% zinc sulfate. The recommended dosage is generally around 50-60 kg per acre. Crops like cotton, rape, beans, and vegetables—being dicotyledonous with large leaf areas and thin cuticles—are more efficient at absorbing nutrients, so their foliar sprays should be less concentrated. In contrast, monocotyledonous crops such as rice, wheat, and corn have smaller leaves with higher silicification, making nutrient absorption slower. Therefore, these crops require a slightly higher concentration for better results.
Third, timing is crucial when applying foliar fertilizers. Studies show that the best time for foliar feeding is during humid conditions when the leaves remain moist for 30–60 minutes. Early morning or late evening, when the air is damp or dew is present, is ideal for maximizing moisture retention. On cloudy or windy days, spraying can be done throughout the day, but evening applications tend to yield the best results. To enhance the effectiveness, adding a small amount of adjuvants like washing powder, neutral soap, or products like 885 fertilizer can reduce surface tension, increase contact area, and improve nutrient absorption.
Fourth, the frequency of foliar applications depends on how mobile the nutrients are within the plant. Nitrogen and potassium are highly mobile, so one spray during critical growth stages is usually sufficient. Phosphorus, being less mobile, may need 1–2 applications depending on crop needs. Micronutrients like zinc, molybdenum, manganese, and copper are only partially transported, while boron and calcium are non-mobile. These elements often require 2–3 consecutive sprays to ensure adequate uptake.
Lastly, the placement of the fertilizer on the plant matters. The green stems and leaves are the primary targets for foliar feeding, especially young, vigorous leaves which absorb nutrients most effectively. Notably, in dicotyledonous crops, the upper surface of the leaves has tightly packed palisade tissue, making it harder for nutrients to penetrate. The underside, however, has a spongy structure with larger cell gaps, allowing better nutrient absorption. Thus, for dicots, it's essential to spray both sides of the leaves. For monocots, spraying only the upper side from the top down is typically sufficient. By following these guidelines, farmers can optimize foliar feeding for healthier and more productive crops.
Standing Wheel Chair,Motorized Standing Wheelchair,Standing Electric Wheel Chair,Automatic Standing Wheelchair
Suzhou Danyazhihe Technology Co., Ltd , https://www.autowheelchairs.com