Page 186 - Enzymes in Tropical Soils

174 Enzymes In Tropical Soils

soil temperature, soil water, soil N, soil aeration, and other factors controlling the
production of enzymes as described previously in the making of organic compost.
Bacause the soil enzymatic activities are dependent on soil organic matter, water,
N, and O 2 , maintaining the high activities of soil enzymes can be conducted by
increasing the soil contents of organic matters, N, water, and O 2 .
In other cases, we may also decrease the soil enzymatic activities, such as
that in the case of Urease. Because Urease may waste the use of Urea N, we
usually inhibit the activity of Urease. There are a great deal of Urease inhibitors
have been reported (Tate III, 1984; Broadbent et al., 1985; Hendrickson and
O’Connor, 1987; Cai et al., 1989; Zhao and Zhou, 1991; Hendrickson and Doughlass,
1993; Sanz-Cobena et al., 2008). In the case of organic soils, in which various
enzymes may degrade the organic structure of the soils, efforts must be done to
lower the production and activities of soil enzymes. One of the method is by
applying heavy metals (Mathur et al.; 1980). Heavy metals may directly interact
with soil enzymes by forming inactive complexes or indirectly by decreasing the
populations of enzyme producing microorganisms.

Important Questions

1. What are the two most important properties of enzymes? Explain them as related to
the decomposition of organic matters in the soil system!
2. The soil enzymatic reactions may follow the zero order or the first order reactions.
Explain!
3. What is Energy of Activation? What is the relation between Energy of Activation and
the role of enzymes in soils? Explain!
4. What is the role of enzymes in supplying plant nutrient elements in the soil system?
5. Why do organic matters or organic residues contain huge amounts of plant nutrent
elements? Explain!
6. What are the good effects of fast decomposition of organic matters catalyzed by
enzymes? Give examples!
7. What are the bad effects of fast decomposition of organic matters catalyzed by soil
enzymes? Give examples!
8. Enzymes in soils can be degraded by several agents or mechanisms. Explain with
examples!
9. Enzymes in soils can be stimulated by several agents or mechanisms. Explain with
examples!

Abdul Kadir Salam - 2014