Page 184 - Enzymes in Tropical Soils

172 Enzymes In Tropical Soils

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).
The soil enzymatic activities may also be stimulated. For example, planting
soils of coffee plantation with P. conjugatum or natural vegetation significantly
increased 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.
To use organic matters as sources of plant nutrient elements in soils, we can
also stimulate the soil enzyme activities. Theoretically, making use of nutrient
elements of organic matters employing enzymes can be done: (a) by composting
the organic matters off-fields before application to the fields or (b) by applying
enzymes into the organic matters to the fields. Composting is to prepare partially
destructed organic matters so that they can be applied more practical with simpler
reactions in soils. In soils, compost may give inorganic elements and decompose
further to more stable forms. However, this method is usually not practical if
compost are applied at high amounts. Organic compost are usually applied in the
-1
soil system at retes of more than 5 – 10 ton ha .
The purified enzymes can be packed to be easily applied in the fields. Upon
treatment into the soil system, the enzymes may dissolve and be activated to
participate in accelerating the decomposisiton or organic matters. The
effectiveness of this biofertilizers is of course controlled by various soil properties
affecting the activities of soil enzymes as mentioned previously.
The enzyme producing organisms can also be packed to be easily applied in
the fields. Upon treatment into soils, the enzyme producing microorganisms may
be activated by some environmental conditions. The soil microorganisms may
develop fast if the environmental conditions are suitable. At this condition, the soil
microorganisms may progress significanty and produce soil enzymes. Therefore, if
constructed properly, this fertilizer is more practical and more effective in
accelelating the decomposition of organic matters.

12.3 Using Soil Properties to Manage Enzymatic Activities

As explained in the previous chapters for enzymes in general terms, the
rates of soil biochemical reactions are also controlled by at least four factors

Abdul Kadir Salam - 2014