Page 101 - Ilmu Tanah

88 The Chemistry and Fertility of Soils under Tropical Weeds

million to one billion soil microorganisms. Therefore, soil microorganisms may
greatly affect the soil dynamics. Most of the soil microorganisms are useful in
agriculture. However, some of them are also pathogen that may give negative
effects on plants.

PLANTS
NUTRIENTS +
(PRODUCERS
CO 2 OF CH 2 O)

SOIL MICRO- ENZYMES ANIMALS/
ORGANISMS HUMANS
(DECOMPOSERS) (CONSUMERS)

ORGANIC
MATTERS
(CH 2 O)

Fig. 6.1. The Carbon-Cycle (After Salam, 2014).

Because its important role in the destruction of organic matters, soil
microorganisms are important not only in the C-Cycle (Fig. 6.1) but also in the
cycles of other nutrient elements (Fig. 1.7, Fig. 1.8, and Fig. 1.9). In the absence of
soil microorganisms, nutrient elements in the residues of plants, animals, and
humans will accumulate and cannot be utilized in the nutrient cycles. This
phenomenon will cause a big problem because, in addition to the organic matter
accumulation, it will also stop the nutrient cycles. In this situation, the supplies of
nutrient elements for plants will be disturbed. Therefore, soil microorganisms
become one of the most important factors in the soil management for agriculture
and environment.
The decomposition of organic matters is speeded by the presence of soil
enzymes produced by microorganisms and other producers like vegetation roots

Abdul Kadir Salam and Nanik Sriyani – 2019