The effects of soil water regime and soil reaction on nitrogen distribution and fractional composition of newly-formed humus (decayed products) and the structural characteristics of the newly-formed humic acids (HAs) ...The effects of soil water regime and soil reaction on nitrogen distribution and fractional composition of newly-formed humus (decayed products) and the structural characteristics of the newly-formed humic acids (HAs) were studied in an incubation experiment, with the following results obtained:1. The humus newly formed under submerged conditions was higher in the relative content of α-amino acid-N and the humic acid/ fulvic acid (HA/ FA) ratio than that under upland conditions. The HAs extracted from the former were also higher in C / O ratio, aromaticity and the contents of methoxyl groups and lignin-like components, but lower in the content of carboxyl groups than the HAs from the latter.2. Under upland conditions, the C / organic N ratio and the relative content of mobile HA of newly-formed humus were lower, but the HA / FA ratio was higher in the CaCO3-amended treatment than in non-amended treatment. The presence of CaCO3 also resulted in a decrease of C / N ratio of HA and a slight increase of its carboxyl group content. On the other hand, there was no significant change in the composition and properties of the newly-formed humus with the addition of CaCO3 under submerged conditions.3. Compared with soil HAs, the newly-formed HAs contained more carbohydrates, polypeptides and lignin-like components, and were in lower degrees of oxidation and humification.展开更多
文摘The effects of soil water regime and soil reaction on nitrogen distribution and fractional composition of newly-formed humus (decayed products) and the structural characteristics of the newly-formed humic acids (HAs) were studied in an incubation experiment, with the following results obtained:1. The humus newly formed under submerged conditions was higher in the relative content of α-amino acid-N and the humic acid/ fulvic acid (HA/ FA) ratio than that under upland conditions. The HAs extracted from the former were also higher in C / O ratio, aromaticity and the contents of methoxyl groups and lignin-like components, but lower in the content of carboxyl groups than the HAs from the latter.2. Under upland conditions, the C / organic N ratio and the relative content of mobile HA of newly-formed humus were lower, but the HA / FA ratio was higher in the CaCO3-amended treatment than in non-amended treatment. The presence of CaCO3 also resulted in a decrease of C / N ratio of HA and a slight increase of its carboxyl group content. On the other hand, there was no significant change in the composition and properties of the newly-formed humus with the addition of CaCO3 under submerged conditions.3. Compared with soil HAs, the newly-formed HAs contained more carbohydrates, polypeptides and lignin-like components, and were in lower degrees of oxidation and humification.
