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60 The Chemistry and Fertility of Soils under Tropical Weeds

(1999b) also show that the activities of enzymes were dependent on types of plants
and length of land cultivation. Root and bacterial phosphatase activities are influenced
by tree species (Cabugao et al., 2017).
Forest fires are also reported to influence the soil enzymatic activity. Saa et al.
(1993) report that wildfires significantly lowered the activity of acid phosphatase
and caused an intense mineralizing effect on organic P, and hence profoundly
increased the inorganic P fractions. However, the controlled fire did not affect acid
phosphatase and only slightly affected the organic P mineralization and the soil
inorganic P fractions. Wildfires are reported to greatly affect the soil organic C and
total N. Abelle and Engel (2013) note that burned areas had significantly greater
soil C and total N than did unburned areas across communities on the landscape of
Mojave Desert.

Table 4.4. The effects of land-use conversion on some soil enzymatic activities in
Sekincau, West Lampung, Indonesia* (After Salam, 2014).

Soil Acid Alkalin -
Urease
Depth Phosphatase Phosphatase Glucosidase
-1 -1
-1
-1
cm g p-Nitrophenol g h g Urea g h
Primary 0 – 20 1,092 ND 158 206
Forest
20 – 40 427 349 38 95

Secondary 0 – 20 419 220 79 138
Forest
20 – 40 387 190 39 88

Coffee 0 – 20 352 209 142 166
Plantation
20 – 40 89 33 26 77

Dry Land 0 – 20 238 153 73 108

20 – 40 72 14 19 63

*Adapted from Salam et al. (1998d); ND Not Determined

Abdul Kadir Salam and Nanik Sriyani – 2019