Growth assistance from the soil
Amongst the plants maize is a late bloomer. In comparison to other crops, for example wheat, the young maize plants grow in a slow pace and need a lot of phosphate in the first couple of weeks. Nevertheless they are unable to acquire the phosphorous in a high quantity and do therefore rely on a constant nutrient flux at the beginning of the growing season to ensure a good harvest.
Therefore at this point in time, in the mid of April when the maize is sown, the sub-soil fertilization is important. Phosphate fertiliser is mixed with magnesium fertiliser, for example Kieserit, and placed in the soil beneath the seeds in form of a fertiliser band. From there it provides the young maize plant via the roots with all the necessary nutrients, even if coldness and compaction limit the nutrient availability. Extremely important is the right distance between the fertiliser and the seeds. Only if the fertiliser band is placed five centimeters besides and five centimeters beneath the seeds salt damages on the seedling can be barred.
The double importance of Magnesium
Sub-soil fertilization does not only feed the maize plants with magnesium but also helps to keep the phosphate available. Phosphates underlie a process of ageing in the soil, which means that they are transferred to less soluble forms and cannot be absorbed after a certain moment in time. Mixing magnesium sulfate (Kieserit) with NP-fertiliser (azotic phosphate fertiliser) leads to formation of a magnesium ammonium phosphate in the soil, the mineral “Struvit” that prevents phosphate from the process of ageing and keeps the phosphate accessible to plants. That guarantees the steady supply of magnesium and phosphor.