Predicting chemical properties of POM in soil cores before and after incubation

The number of pixels associated with POM varied for each hyperspectral image due to the differences in exposed POM area, ranging from 165390 to 451221 pixels per image (Table 2). For soil cores amended with straw, both the distribution of alkyl ratio and C/N were approximately unimodal, indicating a single peak centred around 0.05 - 0.08 for alkyl ratio and 60 - 110 for C/N, with a minor shoulder appearing in both after incubation (Figure 2). Concurring with the measured values of the ROI samples (Table 1), the predicted alkyl ratio of straw were significantly different as a result of the 180-day incubation (Table 3) in both the topsoil and subsoil, with medians slightly increasing from 0.06 to 0.07 (Table 2). Importantly, although the initial alkyl ratio of straw material was initially different between the topsoil and subsoil, the differences in the Kolmogorov-Smirnov D statistic decreased by over 50 % at the end of the incubation, indicating the greater similarity in alkyl ratio of straw added to both two depths (Table 3, Figure 2).