Does Chicory inhibit or promote mineralisation?

Chicory is a perennial herb that has the potential to be incorporated into phased farming systems where lucerne is not well adapted. However, little is known about how chicory will influence the availability of N for the following cropping phase. A 16 week incubation study was conducted with chicory and lucerne plants that had been separated into leaves, stems, fine roots and coarse roots. From the beginning of the experiment all plant components of lucerne except for stems underwent net mineralisation. In contrast, the coarse roots were the only plant component for chicory to undertake net mineralisation from the beginning of the experiment. The stems for both chicory and lucerne did not undergo any net mineralisation during the 16 weeks of the study. Accordingly, the stems only released 1.1 % and 1.7 %, respectively, of N applied in plant material during the study. Despite having a C: N ratio approximately a third of the stems, chicory leaves only released 2.5% of N from plant material, which may be due to the delay in net mineralisation during the first 8 weeks of the incubation. Coarse chicory roots released 10.9 % of N from the plant material, although the C: N ratio was 32.3, which was double that of the lucerne roots. Therefore, chicory leaves actually inhibited net mineralisation during the first 8 weeks of the experiment while coarse chicory roots promoted net mineralisation in comparison to lucerne residues.