Page 81 - Enzymes in Tropical Soils

Enzymes in Tropical Soils 69

SOILPORES

SOIL PORES

SOIL PORES

SOIL SOLIDS SOIL SOLIDS SOIL SOLIDS

A B C

COMPACTION

TILLAGE

Fig. 5.3. Soil compaction and tillage (Adapted from Salam, 2012).

5.2 Differences and Resistence of Organic Matters and
Humus

Organic matters in soils are originated from residues of plants and animals
and dead and decaying plant roots. Organic matter decays change their physical,
chemical, and biochemical properties and also affect the soil physical, chemical,
and biochemical properties and behaviors. The decay processes are accelerated by
the presence of soil enzymes produced by soil microorganisms, soil
macroorganisms, and plant roots, which function as biocatalysators. This processes
release some inorganic constituents that can be absorbed by plants. These
processes continue untill the soil organic matters reach a stable form called humus,
that can not decay further.
In addition to the presence of soil enzymes, the rates of organic matter
decays are also controlled by the organic matters’ C/N ratios. Organic C is needed

Abdul Kadir Salam - 2014