The isotopic timeline of an agricultural field

The so-called crucial field is an agricultural test project west of Copenhagen since 2001, where various fertilizers (such as cattle manure, mineral fertilizer and organic household waste) have been applied on different sub-plots to study their long-term effects. Moreover, some sub-plots have been 'retired' and received only minimal fertilization after 2012. To investigate the numerous effects on C and N isotopes, I am analyzing stored fertilizer, soil and grain samples. The main points of investigation are

1. how the isotopic composition of the soil and the grain changes depending on the fertilizer treatment over time (caused by the fertilizer delta values or alternated soil processes due to fertilization);

2. how the isotopic delta values of the fertilizers themselves have changed since the beginning of the experiment and

3. how long the soil isotopic delta values take to reach pre-experimental values after 'retirement'.

In addition, it is intended to do GHG-flux measurements to investigate emissions of the sub-plots and  examine whether high emissions can be linked to high delta values in the soil.