Anyone who buys spinach or basil in the supermarket only sees products that meet the high demands of consumers. However, there are always challenges to be overcome before they arrive on the shelves. For example, when growing outdoors, heavy rainfall can wash out nutrients from the soil that are necessary for plant growth.
Christian Frerichs, research assistant at Osnabrück University of Applied Sciences, dealt with exactly this problem in his doctorate. This work has now been awarded the doctoral prize of the German Society for Plant Nutrition. The jury praised the practical relevance of the research. “I am very pleased with the award, particularly because I was able to lay the foundation for further scientific research with my results,” says Frerichs.
Basically, a sufficient nitrogen supply is an important prerequisite for producing high-quality vegetables. In his dissertation, Frerichs focused on the cultivation of open-ground spinach and the production of potted basil in greenhouses. However: “Nitrogen is released when fertilizing. This means the more fertilizer is used, the higher the risk that unwanted nitrogen will enter the environment. I wanted to resolve this problem through experimental studies,” Frerichs explains.
In field tests lasting several years, he was able to show that when fertilizing the ground for spinach, timing is crucial in order to reduce potential nitrogen loss. Some of these optimization approaches have already been implemented in practice. At the same time, however, there is still a need for research into the influence of water seepage in winter. This water flows through various layers of soil into the subsoil. It is currently unclear to what extent potential nitrogen losses can be reduced over the seepage period in winter.
Greenhouse protects against seepage but creates other challenges
Typically, potted herbs are grown in greenhouses so that nutrient loss through seepage can be prevented. The limited root space in the pots places high demands on fertilizer management. However, when using organic fertilizers, it is only possible to control how the nutrients are released to a limited extent. This results in nutrient imbalances, which are often accompanied by plant damage. In a series of experiments, Frerichs was able to develop strategies that can significantly reduce these imbalances, thus improving the growth of potted basil.
The most important levers for increasing crop security are the composition of the potting substrates and the type of fertilizer used. The research results so far contribute to more sustainability in cultivation because the relationship between fertilization and yield is better, thanks to the results of the doctorate. In addition to this, more research is now being carried out into the extent to which this can also be transferred to other plants.
Source: Hochschule Osnabrück