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Comparison of the contribution to soil organic matter fractions, particularly carbohydrates, made by plant residues and microbial products
Author(s) -
Murayama Shigetoshi,
Cheshire Martin V.,
Mundie Charles M.,
Sparling Graham P.,
Shepherd Harry
Publication year - 1979
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740301102
Subject(s) - humin , incubation , chemistry , fraction (chemistry) , hydrolysis , acid hydrolysis , organic matter , humic acid , chromatography , biochemistry , organic chemistry , fertilizer
Soil was incubated with 14 C‐ryegrass or 14 C‐glucose, fractionated and the distribution of radioactivity in six fractions and in their constituent sugars was compared. The fractions were (1) the light fraction ( d < 2.00), (2) heavy fraction which was subdivided into (3) HCl soluble, (4) humic acid, (5) fulvic acid, and (6) humin. Sugars were released from soluble fractions by hydrolysis with 0.5M H 2 SO 4 , and from insoluble fractions by hydrolysis with 2.5M H 2 SO 4 and 12M H 2 SO 4 followed by 0.5M H 2 SO 4 . The light fraction contained the greater part of the radioactivity and the sugars in both types of incubation. The proportion of the radioactivity accounted for by sugars in the light fraction of the ryegrass incubation, initially 44%, decreased to 30% after 6 months incubation and to 19% after a year. In one of the glucose incubations, done with soil that had been dried prior to remoistening to 25% w/w and incubating, the proportion was 17% after incubation for one month; in the other, done on soil that had not been given a drying treatment and had a 35% w/w moisture content, it was 32%. In the ryegrass incubation, the sugars with the greatest specific activities were present in the light fraction. In contrast, in the glucose incubation, sugars in the HCl‐soluble, fulvic and humic fractions had the highest specific activities. Carbon from ryegrass contributed more to the humic acid and humin fractions of the soil than did the carbon from glucose, whereas carbon from glucose made a greater contribution to the acid‐soluble organic matter.