Agriculture Reference
In-Depth Information
to decomposition. Similarly, Table I.20 illustrates the decline in concentrations of five
biological nutrient elements and thus the reduction in quality that occurs during the
decomposition of sugarcane harvest residues. Such changes imply a clear overall diminu-
tion in the chemical quality of decomposing materials associated with the increasing
proportion of resistant compounds (Minderman, 1968 and Chapter IV.1.3.3).
Where temperature and moisture conditions do not limit biological activity,
mineralisation is rapid and little resistant material remains after periods of a few months.
This situation is typical of leaf litter dynamics in wet tropical lowland forest situations.
However, when drought, water-logging or low temperatures restrict decomposition,
highly-polymerised chemical compounds
(e.g.,
fulvic and humic acids) may accumulate
and impart a very low chemical quality to the decomposing material. This is a common
situation in cold and temperate-climate regions.
In some circumstances, resource quality may increase over time, following the removal
of strong chemical or physical constraints to decomposition (Heal and Dighton, 1985)
(Figure 1.41 and see Chapter IV. 1).
