In the present paper, the composition of humus and the charateHstics of humic acid from seven paddy soils were compared with those of upland (and / or natural) soils. Results show that :(1) in each group of the soil s...In the present paper, the composition of humus and the charateHstics of humic acid from seven paddy soils were compared with those of upland (and / or natural) soils. Results show that :(1) in each group of the soil samples for comparison the HA / FA ratio of the humus of a paddy soil, in most cases, was appreciably higher than that of adjacent upland (and / or natural) soil derived from the same parent material; (2) the humic acid extracted from the paddy soils was characterized by a higher C/ O ratio, a higher content of methoxyl groups, and a lower content of carboxyl groups than those from the corresponding upland (and / or natural) flooded soils, implying that the humic acid formed under rice cultivation is in a lower degree of humification than that formed under upland (and / or natural) conditions; and (3) the humic acid of paddy soils, however, was not always characterized by a lower aromaticity than that of the corresponding upland (and / or natural) soils.展开更多
文摘In the present paper, the composition of humus and the charateHstics of humic acid from seven paddy soils were compared with those of upland (and / or natural) soils. Results show that :(1) in each group of the soil samples for comparison the HA / FA ratio of the humus of a paddy soil, in most cases, was appreciably higher than that of adjacent upland (and / or natural) soil derived from the same parent material; (2) the humic acid extracted from the paddy soils was characterized by a higher C/ O ratio, a higher content of methoxyl groups, and a lower content of carboxyl groups than those from the corresponding upland (and / or natural) flooded soils, implying that the humic acid formed under rice cultivation is in a lower degree of humification than that formed under upland (and / or natural) conditions; and (3) the humic acid of paddy soils, however, was not always characterized by a lower aromaticity than that of the corresponding upland (and / or natural) soils.
