Semi-field trial at Aarhus University
A semi-field experiment was conducted to test the effect of long-term compost application at varying fertilizer levels on soil quality and lettuce growth. To this end, square plastic boxes with open bottoms were inserted into the ground at the AU-FOOD research centre. These boxes were filled with soil that had a history of long-term compost application and with soil without compost application. In addition, compost was applied to the long-term compost soil at the start of the experiment.
In 2019, lettuce was planted into the boxes. Four different fertilizer levels were applied. Soil mineral N, potential N mineralization and soil microbial activity were measured at the start and at the end of the experiment. Root growth was assessed regularly at observation windows that were inserted at one side of the boxes (see picture). Lettuce biomass and N content were measured at the end of the experimental period.
Setting up the semi field trial at Aarhus university (source: Aarhus University)