Fertilisation during tillage and seeding
Ensuring a safe and sufficient nutrient supply of the crops throughout the entire growing season is becoming increasingly important in view of the extreme weather conditions we are facing. Efficient and sustainable nutrient management is not just about replacing the elements that are removed during the harvest. In the future, the availability of nutrients throughout the entire growing season will be the major challenge.
Whereas previously, placed fertilisation mainly focused on the nutrients N and P which also have a direct influence on root development, other elements are now coming to the fore in the sector of deep fertilisation. Especially on high-yield sites for grain maize cultivation, the discussion is increasingly turning to the deeper application of potassium, sulphur and magnesium. Worldwide, we notice a shift towards the increasingly frequent use of placed fertilisation. It influences both plant and root development.
Early growth
Contact fertilisation and traditional underground fertilisation in particular have a major influence on the early growth of crops. In recent years, resistance to herbicides has been increasing in many regions, particularly among weeds, but also among grass weeds. Therefore, the seeding date is often postponed. Strong and competitive young crops have an advantage in terms of natural competitiveness. Even for rapeseed which often greatly suffers from flea beetles in its early stages, rapid growth in the early stages is optimal so that the plant can outgrow the sensitive stages as quickly as possible.
Rapid early growth is even more crucial for spring crops, especially in adverse weather conditions. Particularly in regions with cold or cold and wet emergence conditions, contact or underground fertilisation provides protection for a rapid initial crop development. The foundation for yield is laid at this early stage.
Downward root growth
In addition to the rapid initial development, downward root growth is another important factor for water and nutrient uptake. To prevent the roots from spreading only in the top layer, nutrients that are placed deeper can attract the roots downward. If the upper nutrient-rich layer (e.g. 10 cm) desiccates because of weeks of drought, the plants can feed sufficiently from the deeply stored nutrient depot via their deeper roots and cope better with the drought stress.
In order to draw the roots into deeper zones, the deep placement of phosphatic fertiliser in the lower topsoil zone proved to be particularly advantageous for rapeseed. The photo of the rapeseed root clearly shows how the roots are attracted to deeper layers and how they ramify.
Roots that have been quickly attracted to deeper soil layers can then ensure the water supply for the plants in dry conditions. Deep fertiliser placement (approx. 25 cm) has a positive effect on root development and nutrient supply, and not only for taproots. Other crops, e.g. maize as a spring crop, can also benefit from nutrients that are placed deeply in the soil. This type of fertilisation is one of the most effective ways of providing nutrients for the plant.
Placed fertilisation
Encouraging early growth: Targeted fertilisation in the immediate vicinity of the seed (contact or underground fertilisation) will encourage early growth. This can support the establishment of the population, especially in cold resp. cold and wet emergence conditions.
Stimulating root growth: Deep fertilisation encourages the development of the root system. This improves the water supply during dry periods and allows for developing a larger soil volume for the nutrient uptake.
Improved nutrient utilisation: Improved nutrient utilisation: By placing nutrients specifically in the root zone, plants can absorb them more quickly and efficiently. This significantly improves nutrient availability for plants, especially in fixing locations.
Deep placement of nutrients
In some countries, we also observe that fertiliser is applied even more deeply (approx. 40 cm) and in higher quantities. The aim also is to use nutrients as effectively as possible. In addition to the well-known discussion about nitrogen and phosphorus, potassium, sulphur and magnesium are now also added in these regions. The fertiliser is placed in a concentrated band and remains available to the plant for a longer period of time. Especially on fixing soils, this type of band placement offers an enormous advantage for fertilisation efficiency.
Deep fertilisation is always accompanied by a certain amount of loosening. It is important that the slot created by the cultivator tine is closed again and consolidated. If cavities remain in the soil after cultivation, fine soil is displaced to the bottom of the slot by precipitation, creating a new compaction zone. In addition, the fine soil fixes the nutrients, limiting their availability to the plants. Especially on heavier sites, the consolidation of the slot is necessary to keep the nutrients available.
In general, placing fertiliser in the deeper topsoil layer ensures that the plants are nourished. Increasingly long periods of drought cause the upper layer of topsoil to desiccate and, if there is a lack of nutrients in the subsoil, will result in the starving of the plant.
