What is the correct method for applying potassium fertilizer to vegetables?
How do you apply potassium fertilizer when growing vegetables? What should you pay attention to? Potassium is one of the three essential fertilizer elements. Many vegetables need more potassium than nitrogen or phosphorus. Well-grown vegetables contain potassium at 2.5%-7% of their dry matter, higher than their nitrogen and phosphorus content. Most vegetables absorb more potassium than nitrogen. For example, cucumber absorbs nitrogen...
How do you apply potassium fertilizer when growing vegetables? What should you pay attention to?
Potassium is one of the three essential fertilizer elements. Many vegetables need more potassium than nitrogen or phosphorus. Well-grown vegetables contain potassium at 2.5%-7% of their dry matter, higher than their nitrogen and phosphorus content. Most vegetables absorb more potassium than nitrogen. For example, the nitrogen-to-potassium ratio absorbed by cucumber is 1:(1.5-1.7), pumpkin 1:2.1, tomato 1:1.9, eggplant 1:(1.5-1.65), green pepper 1:1.3, carrot 1:(1.1-1.3), radish 1:(1.1-1.35), onion 1:(1.1-1.4), lettuce 1:(1.6-1.9), and cabbage 1:(1.1-1.3).
Some of the potassium applied to the soil is fixed into forms that are difficult to absorb, and some becomes exchangeable potassium that vegetables can readily absorb. In practice, only about 50% of the applied potassium fertilizer is absorbed and used by vegetables. Generally speaking, potassium availability is higher in sandy soil than in clay soil, and lower in calcareous soil.
The potassium concentration most suitable for vegetable growth is about 5% of the soil's total exchangeable potassium. When the soil's exchangeable potassium content is low, such as below 85mg/kg for sandy soil, below 100mg/kg for sandy loam and loam, and below 125mg/kg for clay, applying potassium fertilizer has a good effect on increasing vegetable yield and improving quality.
The conventional potassium application rate is 0.8-1.5 times the amount absorbed by vegetables. Most vegetables are given equal amounts of nitrogen, phosphorus and potassium as a base fertilizer, generally 10-15kg of potassium oxide per 667 sq m, but when nitrogen fertilizer is increased, the potassium fertilizer rate must also be raised. For potassium-demanding vegetables such as solanaceous fruits and cucurbits, be sure to increase the proportion of potassium fertilizer, and after the base fertilizer is applied in full, apply potassium fertilizer as a timely and appropriately measured top dressing later on. For fruit vegetables, it is best for the potassium top dressing to account for 50-60% of the total potassium applied.
There are many types of potassium fertilizer, and different types have different application methods. Commonly used potassium fertilizers include potassium chloride, potassium sulfate, potassium-magnesium fertilizer and plant ash. Potassium chloride and potassium sulfate are physiologically acidic fertilizers and should be applied together with lime and organic fertilizer. For chlorine-sensitive crops such as potato, potassium chloride and potassium-magnesium fertilizer with a high chlorine content should not be applied. Potassium-magnesium fertilizer is suitable for acidic soil. Plant ash is suitable for vegetable seedling raising, as it both supplies nutrients and absorbs heat to raise the soil surface temperature, promoting early seedling growth. In addition, using a 1% plant ash extract as a foliar top dressing also has a good effect on controlling vegetable aphids. According to trials, hole application, furrow application and band application are more effective than broadcasting. Generally, potassium is applied 10cm from the vegetable roots, which both avoids burning the roots and helps the plants absorb potassium.
Click to get more nitrogen, phosphorus and potassium fertilizer application techniques
Click to get more fertilizer application techniques
Click to get more vegetable growing techniques