Potassium fertilization of maize
Maize in the growing season accumulates a large vegetative mass, which makes the needs of plants in relation to nutrients high. Plants show the highest demand for nitrogen and potassium.
Importance of potassium
Potassium plays an important role in the photosynthesis and transport of assimilates and in the water management of maize. Plants well-fed with potassium are more resistant to more frequent droughts caused by hot weather and lack of rainfall. Potassium also has a positive effect on the development of the root system, which allows better uptake of water and nutrients from the soil. This nutrient is also responsible for the processing of nitrogen by the plants. Potassium also contributes to a better filling of the grain and a lower moisture content during harvesting. The uptake of potassium depends on the availability of other ingredients, especially nitrogen. On the other hand, a good supply of potassium to plants increases their reaction to nitrogen fertilization. Well nourished plants are more resistant to lodging, diseases and pest infestation.
Potassium deficiency is manifested by unnatural, dark green colouring of older leaves, necroses on their top and edges. The top of the cob is poorly formed with kernels loosely embedded in the cob. During the heat, the plants wilt earlier and longer regain their turgor.
Rules of maize fertilization with potassium
Potassium doses in maize cultivation are 60-120 kg K2O/ha for grain maize and 80-160 kg K2O/ha for feed maize. When fertilizing maize with potassium, the entire crop rotation must be fertilized, as this is a plant that reacts more strongly to the available potassium content of the soil than to the pre-sowing fertilization. Therefore, it is important to try to bring the soil abundance to the level of medium class. The dose of potassium under maize should be about 1/5 of the total dose in the crop rotation. It is particularly important to assess the soil abundance when maize is cultivated in monoculture for silage, where a significant volume of nutrients is taken out of the field together with forage.
Maize fertilization* depending on soil type and expected yields
|
Soil type | Yield in grain of grain maize and CCM, dt/ha | Yield in dry matter of feed maize, dt/ha | ||||
|---|---|---|---|---|---|---|
| | 40-50 | 60-70 | 80-100 | 100-120 | 130-150 | 160-180 |
| N, kg/ha | ||||||
| Heavy, fertile, abundant | 120 | 140 | 160 | 140 | 160 | 180 |
| Medium, medium rich | 110 | 125 | 140 | 120 | 140 | 160 |
| Light, low in abundance | 100 | 110 | – | 100 | 120 | 140 |
| P2O5, kg/ha | ||||||
| Heavy, fertile, abundant | 40 | 60 | 80 | 30 | 40 | 50 |
| Medium, medium rich | 60 | 80 | 100 | 60 | 70 | 80 |
| Ligh low in abundance | 80 | 100 | – | 90 | 110 | 130 |
| K2O, kg/ha | ||||||
| Heavy, fertile, abundant | 60 | 70 | 80 | 80 | 90 | 100 |
| Medium, medium rich | 80 | 90 | 100 | 100 | 110 | 130 |
| Light, low in abundance | 100 | 120 | – | 120 | 130 | 160 |
| * only mineral fertilizers | ||||||
Since maize is neutral to chlorine, potassium salt should be used as a fertilizer. Potassium salt is best used in the whole dose for pre-winter ploughing. It can also be sown to the stubble after harvest. Only on lighter soils, where the risk of leaching and loss of potassium is higher, 2/3 of the dose should be applied in autumn and the remaining 1/3 in spring. If the fertilizer is not applied in autumn, it should be sown as early as possible in spring and mixed with soil to a depth of 10-15 cm during pre-sowing cultivation.
The average increase in maize grain yield obtained in the SGGW experiment after applying 80 kg K2O/ha in relation to control (without potassium) was 2.5 t/ha, i.e. 27%.
Written by dr inż. Arkadiusz Artyszak