Page 171 - Enzymes in Tropical Soils

Enzymes in Tropical Soils 159

The changes in the soil enzymatic activities were well correlated with the
changes in the soil organic C and total N. These data indicate the importance on C
and N for soil microorganisms, that produce most of the soil enzymes. As discussed
previously, organic C is an energy source for soil microorganisms while N is needed
to form proteins. Therefore, the presence of lower C and N in the degraded lands
may cause lower populations and activities of soil microorganisms and, thereby,
produce less enzymes. As previously shown, several experimental data support
this thesis. The results indicates that the soil enzymatic activities may be enhanced
by addition of organic C (Klein and Koths, 1980; Nannipieri et al., 1980; Harrison,
1983; Trasar-Cepeda and Gil-Sotres, 1987; Bonmati et al., 1991; Tate III et al., 1991;
Martens et al., 1992; Salam, 1996; Deng and Tabatabai, 1996; Salam et al., 1998d;
1999d; 1999e).
For example, planting soils of coffee plantation with Paspalum conjugatum
or natural vegetation significantly increase the organic C and total N content after 3
years (Table 10.7). The increase in organic C and total N accordingly increased the
soil enzymatic activities as shown in Table 10.7 (Salam, 1996; Salam et al., 2001).
Salam et al. (1999d; 1999e) stated that the activity of phosphatase increased in
correlation with the increase in soil organic C and total N contents.

Table 10.7. The effects of vegetation on some soil ezymatic activities of coffee plantations
in West Lampung Indonesia*

Ac. Phosp. Alk. Phosp. -Gluc. Arylsulf.
Soil Layer
1997 1999 1997 1999 1997 1999 1997 1999

A. No Vegetation (Control)
Topsoil 123 107 36 44 123 67 458 48
Subsoil 73 109 19 24 76 67 206 72

B. Grass (Paspalum conjugatum)
Topsoil 322 145 104 45 157 117 97 149
Subsoil 281 126 74 30 100 63 21 157

C. Natural Vegetation
Topsoil 271 156 36 54 168 129 165 143
Subsoil 284 122 27 26 191 60 139 148
-1 -1
*Adapted from Salam et al. (2001); in mg p-Nitrophenol g h

Abdul Kadir Salam - 2014